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View Full Version : Blower door test & Combustion analysis done today...1st stage more efficient

key1cc
05-07-2009, 06:46 PM
I had my first Blower door test and Combustion analysis test done today as part of a NJ state sponsored energy Audit. I have nothing but praise for the BPI accredited Pro that did the work (and it is not because he offered me a job:)...twice :cool:, Thanks HVAC-Talk for my education in this area. Best \$125 I ever spent for 4 solid hours of work. If it was not state sponsored it would cost much more...If you live in NJ I reccomend you take advantage of this opportunity.

Ok, now lets get dow to business. I will start with the combustion analysis since I have participated in some very intense and excellent threads on the subject of whether 1st or 2nd stage is more efficient.

The tech used a Bacharach combustion analyzer and checked both 1st and 2nd stage heating operation. Oh before I forget, I have a 100k BTU Trane XV95 furnace and a 4 ton XL15i AC with matched 5 ton ADP coil.

Here are the numbers for 1st stage:
Stack temp = 90
O2 = 8.4
CO2= 7.1
ambient temp = 72
CO= 5 ppm
Efficiency = 98.3

Here are the stage 2 numbers
Stack temp = 105
O2 = 8.3
CO2 = 7.2
ambient = 74
CO= 4 ppm
efficiency = 95.0

I know the O2 numbers is not as low as 6.0 like the great Jim Davis likes to shoot for but what do you think?

I have to run for about 45 minutes will be back to post more data.

Key1

beenthere
05-07-2009, 07:03 PM

bdivell
05-07-2009, 07:05 PM
not 100 % but i am pretty sure o2 can be from 5 to 9 range i would have to look in my books/notes....but i'd say looks good ... have to be happy with those readings

fenian
05-07-2009, 07:22 PM
I'm not sure jim puts weight into those efficiency numbers given he uses a temp rise times cfm equation. If he's online he'll speak for himself.

out of curiosity do you have the cfm/ temp rise for both stages?

Congrats on the positive experience with the audit.

key1cc
05-07-2009, 07:49 PM

It was 77 degrees here today and we had the basement windows open for a while so it could have been the basement temp but I am not sure. The reading was taken right off of the meter while the probe was inserted in the pvc exhaust pipe. I will receive the full comprehensive report in about a week.
Key1

key1cc
05-07-2009, 07:50 PM
I'm not sure jim puts weight into those efficiency numbers given he uses a temp rise times cfm equation. If he's online he'll speak for himself.

out of curiosity do you have the cfm/ temp rise for both stages?

Congrats on the positive experience with the audit.

not 100 % but i am pretty sure o2 can be from 5 to 9 range i would have to look in my books/notes....but i'd say looks good ... have to be happy with those readings

Thanks for the feedback. The CFM for stage 1 is 1000 CFM and the ESP is 0.43 and the max temp rise is 61F

The CFM for stage 2 is ~1500 esp = 0.98, temp rise ?

Key1

key1cc
05-07-2009, 08:11 PM
Now for the blower door test data.
According to BAS (building airflow standard) and MVG (minimum ventilation guidlines) the standard airflow number for a property the size of mine is 2864.
The actual value obtained with the test was 3400. I am not clear on this but I beleive it means my leak rate is the difference between the two numbers. He used the Minneapolis Blower Door machine and set if for -50 pascals. The machine put the house under negative pressure then we went around with a hand held smoke generator to indentify the leaks. I was suprised at the leakage due to the outlets and light switches on interior walls as well as exterior. My comprehensive report is due in a week.
Key1

sktn77a
05-07-2009, 08:32 PM
Jim will probably say those numbers are meaningless as they don't define the heat delivery to the system. However, given the first law of thermodynamics, I'd say that they fly in the face of all those people who claimed the low stage efficiency was as low as 50%!

paul42
05-07-2009, 10:00 PM
Now for the blower door test data.
According to BAS (building airflow standard) and MVG (minimum ventilation guidlines) the standard airflow number for a property the size of mine is 2864.
The actual value obtained with the test was 3400. I am not clear on this but I beleive it means my leak rate is the difference between the two numbers. He used the Minneapolis Blower Door machine and set if for -50 pascals. The machine put the house under negative pressure then we went around with a hand held smoke generator to indentify the leaks. I was suprised at the leakage due to the outlets and light switches on interior walls as well as exterior. My comprehensive report is due in a week.
Key1

drywall is very flat, standard construction 2x4's are not. The inevitable result is lots of small cracks and air leaks, between the top plate and the drywall at the ceiling to attic plane.

mbarson
05-07-2009, 11:05 PM
The lower O2 reading on second stage prove that second stage is more efficient but there is still too much excess air. Those efficiency numbers you posted are not correct as they are calculated efficiency not burner efficiency or delivered efficiency. The truth is that with latent losses, excess oxygen, and flue temp losses the actual efficiency will never be over 90%. If you get your O2 down to 6% you may up the efficiency to 105% or better! Your blower door data does not give you any useful information by itself. You need to correlate it with the volume and floor area of the house. This will tell you your ACH50 and can be converted to ACHnat to show how leaky the house is. You will most likely get these numbers in your report.

key1cc
05-08-2009, 08:26 AM
drywall is very flat, standard construction 2x4's are not. The inevitable result is lots of small cracks and air leaks, between the top plate and the drywall at the ceiling to attic plane.

Agreed. And in addition, the bottom plate (rim joist?) and the foundation in the basement. These are typically large sources or air leakage.
Key1

motoguy128
05-08-2009, 08:38 AM
Jim will probably say those numbers are meaningless as they don't define the heat delivery to the system. However, given the first law of thermodynamics, I'd say that they fly in the face of all those people who claimed the low stage efficiency was as low as 50%!

It rediculous to even think for a second that the 1st stage on a condensing furnce is 50%. Why? Because if you're condensing water vapor out of the flue gases, you're at least 85% or greater or have really high air flow rates. Second, everyone's bill with a 2 stage furnace that runs in low stage most of the time, would be really high.

I think higher efficincy on 1st stage is logical. You basically have an oversized heat exchanger.

If I stick a bigger radiator in my car, and bypass the thermostat, what happens? the discharge water temp out of the radiator will be lower at the same engine load and airlfow rate.

So the only way it would be less efficient is if there was proportionally less airflow on low stage. I believe there is proportionally more airflow, because the temp rise is usually lower on 1st stage than 2nd. On my XV80, for example, the 1st stage airlfow is only 75% of 2nd stage, but the BTU's are 65% of 1st stage. So the rate temp rise is 6 degrees lower.

Good to see that there's some data to prove what makes sense logically.

key1cc
05-08-2009, 08:47 AM
Your blower door data does not give you any useful information by itself. You need to correlate it with the volume and floor area of the house. This will tell you your ACH50 and can be converted to ACHnat to show how leaky the house is. You will most likely get these numbers in your report.

I spent some time yesterday reviewing my notes and I beleive I have a better understanding of the data.
First my living space of 2800 sq.ft is added to the basement space of 1300 sq. ft for a total of 4100 sq. ft.. next a few calculations are done that considers my stories above grade (2) and my location (NJ) and the number of residents in my house (3) and the height of my walls (8ft). The result is 191 CFM ventilation is required for my building.Then that gets converted to the "minimum CFM50" by multiplying by a factor based on my location (in the U.S. or Canada) and the height correction for my 2 story home.

After all of this we get a minimum CFM50 requirement of 2864 as I listed in a earlier post. Next my actual reading was done with a house negative pressure set to -50 pascals. The result was 3400 CFM. If the result would have been less than 2864 CFM they would reccomend a fresh air intake. If the result would have been significantly lower (below 70% of the CFM50 requirement) then they would insist a fresh air intake is installed.

Since my value was higher (3400) than the requirement (2864) then there is room for me to reduce my leakage without a fresh air intake as long as I don't take the value below (2864).

Key1

sktn77a
05-08-2009, 09:31 AM
It rediculous to even think for a second that the 1st stage on a condensing furnce is 50%. Why? Because if you're condensing water vapor out of the flue gases, you're at least 85% or greater or have really high air flow rates. Second, everyone's bill with a 2 stage furnace that runs in low stage most of the time, would be really high.

Absolutely! And this was the argument used back then, but endless debate obfuscated logic!

TMH58
05-08-2009, 09:46 AM
CO2 levels must be below 10. I find it a little hard to believe you are getting 7 ppm CO. That is very good levels. In most states, below 100 is acceptable. Of course, if it were over 40, I would be looking at flame impingement,alignment,etc.

phbsales
05-08-2009, 09:51 AM
Here are the numbers for 1st stage:
Stack temp = 90
O2 = 8.4
CO2= 7.1
ambient temp = 72
CO= 5 ppm
Efficiency = 98.3

Here are the stage 2 numbers
Stack temp = 105
O2 = 8.3
CO2 = 7.2
ambient = 74
CO= 4 ppm
efficiency = 95.0

I know the O2 numbers is not as low as 6.0 like the great Jim Davis likes to shoot for but what do you think?

Key1

You are possibly under-fired. Your stack temps are too low. They should be between 120* and 140*. Your O2 readings are closer to the 9% range also indicating that you could be under-fired. Your CO readings as low as they are also indicating a possible low-fire situation.

Sounds to me, this furnace could use a little tweaking. :D

key1cc
05-08-2009, 10:53 AM
You are possibly under-fired. Your stack temps are too low. They should be between 120* and 140*. Your O2 readings are closer to the 9% range also indicating that you could be under-fired. Your CO readings as low as they are also indicating a possible low-fire situation.

Sounds to me, this furnace could use a little tweaking. :D

Now thats the kind of feedback I was hoping for.
When I "clocked" my gas meter ( by turning off all gas appliances and only letting the furnace run), I realized my manifold gas pressure could use adjusting because I only clocked 60,000 btu incoming on low fire and 89,000 btu incoming on high fire. My capacaity should be 65k and 100k incoming and 95k and 61750 k out.

Is it worthwhile to have the manifold pressures tweaked up a bit?

Key1

TMH58
05-08-2009, 11:27 AM
It is a good idea to set your manifold pressures to reccommended factory setitings. Most manufacturers have a low btu gas setting and a high btu gas setting. You should never set manifold pressures higher than factory reccomendations. Also, the only way to check true AFUE ratings is in a lab. The ratings you read with a combustion analyser are usually lower. Alot of factors come in to play like vent pipe size and length, btu content, burner alignment,etc.

beenthere
05-08-2009, 11:33 AM
Depends on what your temp rise is to teh CFM of air.

key1cc
05-08-2009, 12:06 PM
Depends on what your temp rise is to teh CFM of air.

Good point.

I already have a 61F temp rise with a range of 35-65.

...would not want to exceed the 65 and have the limit switch start tripping.

Key1

teddy bear
05-08-2009, 12:08 PM
I spent some time yesterday reviewing my notes and I beleive I have a better understanding of the data.
First my living space of 2800 sq.ft is added to the basement space of 1300 sq. ft for a total of 4100 sq. ft.. next a few calculations are done that considers my stories above grade (2) and my location (NJ) and the number of residents in my house (3) and the height of my walls (8ft). The result is 191 CFM ventilation is required for my building.Then that gets converted to the "minimum CFM50" by multiplying by a factor based on my location (in the U.S. or Canada) and the height correction for my 2 story home.

After all of this we get a minimum CFM50 requirement of 2864 as I listed in a earlier post. Next my actual reading was done with a house negative pressure set to -50 pascals. The result was 3400 CFM. If the result would have been less than 2864 CFM they would reccomend a fresh air intake. If the result would have been significantly lower (below 70% of the CFM50 requirement) then they would insist a fresh air intake is installed.

Since my value was higher (3400) than the requirement (2864) then there is room for me to reduce my leakage without a fresh air intake as long as I don't take the value below (2864).

Key1
The natural air leakage cfm is for a average winter day and 7.5 mph wind. And yes no fresh air ventilation required "on an average winter day/wind 7.5 mph wind". The stack effect and wind cause internal/external negatuve/positive pressures to move air. What is the natural leakage on 55^F day without wind or an average summer day with wind and without? Much less to none on a calm day when inside/outside temps are the same. Your home is not adequately ventilated to purge indoor pollutants and renew oxygen on any calm windless day at warmer termperatures. I have a similar home in WI that I have tested extensively using CO2 as a tracer gas during various weather conditions to determine my real air change. The Blower Door test assume that all the leaks are distributed throughout the home. If all the air leaks where on a single level, the stack effect would have much less effect. The same for wind effect, if the air leaks are on side of the home, the air leakage is much less. Regards TB

beenthere
05-08-2009, 12:14 PM
At a 61°F delta, at 1000CFM, that would give you an output of 65,880BTUs.

If that first stage.

Either you aren't moving the CFM you listed. Or the input is higher then you think. Or the temp rise is not what you posted.

key1cc
05-08-2009, 12:26 PM
The natural air leakage cfm is for a average winter day and 7.5 mph wind. And yes no fresh air ventilation required "on an average winter day/wind 7.5 mph wind". The stack effect and wind cause internal/external negatuve/positive pressures to move air. What is the natural leakage on 55^F day without wind or an average summer day with wind and without? Much less to none on a calm day when inside/outside temps are the same. Your home is not adequately ventilated to purge indoor pollutants and renew oxygen on any calm windless day at warmer termperatures. I have a similar home in WI that I have tested extensively using CO2 as a tracer gas during various weather conditions to determine my real air change. The Blower Door test assume that all the leaks are distributed throughout the home. If all the air leaks where on a single level, the stack effect would have much less effect. The same for wind effect, if the air leaks are on side of the home, the air leakage is much less. Regards TB

Sooooo you are saying that my door test is only one data point and based on your experience, as the conditions change my results will change....and that I should connect my fresh air intake (which is installed and capped and not currently connected to the return drop) so that when the conditions warrent I can have the proper ventallation?
Key1

key1cc
05-08-2009, 12:29 PM
At a 61°F delta, at 1000CFM, that would give you an output of 65,880BTUs.

If that first stage.

Either you aren't moving the CFM you listed. Or the input is higher then you think. Or the temp rise is not what you posted.

If I had to guess I would say I am probally not moving the 1000 CFM since that number is inferred while the temp rise is measured in the hottest location of 4 that were checked.
Key1

phbsales
05-08-2009, 02:41 PM
Now thats the kind of feedback I was hoping for.
When I "clocked" my gas meter ( by turning off all gas appliances and only letting the furnace run), I realized my manifold gas pressure could use adjusting because I only clocked 60,000 btu incoming on low fire and 89,000 btu incoming on high fire. My capacaity should be 65k and 100k incoming and 95k and 61750 k out.

Is it worthwhile to have the manifold pressures tweaked up a bit?

Key1

Just remember, there are only 2 things you can adjust. Fuel and air. They can be adjusted only 2 ways. Up or down.

phbsales
05-08-2009, 02:45 PM
Sooooo you are saying that my door test is only one data point and based on your experience, as the conditions change my results will change....and that I should connect my fresh air intake (which is installed and capped and not currently connected to the return drop) so that when the conditions warrent I can have the proper ventallation?
Key1

Air is stupid. It must be controlled. By connecting the fresh air intake to the return ductwork (and add a small supply on the plenum) you are now beginning to introduce positive pressure on the building envelope.

beenthere
05-08-2009, 03:28 PM
Just remember, there are only 2 things you can adjust. Fuel and air. They can be adjusted only 2 ways. Up or down. You have more ways to adjust the fuel other than adjusting . :cool:

Be carefull what you post about making alterations for combustion.
You went into DIY combustion control.

I edited it out.

phbsales
05-08-2009, 03:34 PM
Be carefull what you post about making alterations for combustion.
You went into DIY combustion control.

I edited it out.

Sorry about that. I wasn't thinking. :o

key1cc
05-08-2009, 04:03 PM
Be carefull what you post about making alterations for combustion.
You went into DIY combustion control.

I edited it out.

No wonder it did not make sense :rolleyes:

Key1

phbsales
05-08-2009, 04:08 PM
Have you taken Jim Davis' combustion course?

:cool:

key1cc
05-08-2009, 04:53 PM
Have you taken Jim Davis' combustion course?

:cool:

Thanks phbsales. Your insight is quite valuable.
I have not taken the course....but my email address is in my profile if you want to provide me some details on the course :).
Actually, Jim sent me a private link to the course several months back when they were in Philly.....The timing did not work for me.
Key1

key1cc
05-08-2009, 04:56 PM
Air is stupid. It must be controlled. By connecting the fresh air intake to the return ductwork (and add a small supply on the plenum) you are now beginning to introduce positive pressure on the building envelope.

I wont ask how because I understand that is against the rules but I will ask Why...

Why add the small supply on the plenum?
What value does it bring?

Key1cc

davidr
05-08-2009, 05:35 PM
Sooooo you are saying that my door test is only one data point and based on your experience, as the conditions change my results will change....and that I should connect my fresh air intake (which is installed and capped and not currently connected to the return drop) so that when the conditions warrent I can have the proper ventallation?
Key1

You'll never have conditions where all six sides of the building enclosure are depressurized with the only exit point being a 20" fan.

Depending on weather conditions one side of the structure could be depressurized while the other side is pressurized.
This is just one of many variations that could occur.

Connecting your fresh air intake will allow you to reduce any stack effect on your home but could have side effects depending on where you live.
The register in the supply plenum is to provide a "pressurized" space for any combustion appliances that are using interior air for combustion.

Not enough information is being provided to you to judge your equipment or system performance. Sure would be nice if they have more readings to provide you with key.

Be careful with those delta T numbers, temperature readings can vary as much as 30º in a supply plenum. :)

key1cc
05-08-2009, 08:06 PM
You'll never have conditions where all six sides of the building enclosure are depressurized with the only exit point being a 20" fan.

Depending on weather conditions one side of the structure could be depressurized while the other side is pressurized.
This is just one of many variations that could occur.

Connecting your fresh air intake will allow you to reduce any stack effect on your home but could have side effects depending on where you live.
The register in the supply plenum is to provide a "pressurized" space for any combustion appliances that are using interior air for combustion.

Not enough information is being provided to you to judge your equipment or system performance. Sure would be nice if they have more readings to provide you with key.

Be careful with those delta T numbers, temperature readings can vary as much as 30º in a supply plenum.

Thanks for the feedback. It sounds like you and Teddy Bear are aligned in your thinking for my blower door test.

My question is with your comment on providing a pressurized space by adding a register in my basement. If my fresh air intake is connected to the return ....would'nt the entire house be a "pressurized space"?

I hear you loud and clear on the delta T numbers. There are 3 trunks that come off of my plenum delta T numbers were taken in all three and the location with the highest temp was selected as the appropriate spot.

Key1

davidr
05-09-2009, 08:47 AM
Thanks for the feedback. It sounds like you and Teddy Bear are aligned in your thinking for my blower door test.

My question is with your comment on providing a pressurized space by adding a register in my basement. If my fresh air intake is connected to the return ....would'nt the entire house be a "pressurized space"?

I hear you loud and clear on the delta T numbers. There are 3 trunks that come off of my plenum delta T numbers were taken in all three and the location with the highest temp was selected as the appropriate spot.

Key1

The outdoor air intake "should" pressurize the building enclosure but depending on duct leakage and other variables in your home it might not be performing like you think it is.

To quote my favorite Canadian "You can't pressurize Swiss cheese." :)

A quick test with the digital micromanometer your blower door operator was using could have verified how well it was pressurizing pretty quickly.

key1cc
05-09-2009, 09:31 AM
At a 61°F delta, at 1000CFM, that would give you an output of 65,880BTUs.

If that first stage.

Either you aren't moving the CFM you listed. Or the input is higher then you think. Or the temp rise is not what you posted.

Hey Been, as usual you were correct. After a good night sleep it came to me what could possibly cause the discrepancy. My temp rise numbers and all other measurements are made with my humidifier bypass wide open. I leave it on and open all winter. The recirculating heat probally pushed my heat rise temp up higher than the true value. "Your the man"! :cool:

Key1

key1cc
05-09-2009, 10:15 AM
A quick test with the digital micromanometer your blower door operator was using could have verified how well it was pressurizing pretty quickly.

I thought about that but he had already spent close to 4 hours here and he still had not yet checked the oven and the garage/family room attic yet.

He will be giving me a quote on some reccomended work which involves dense packing cellulose in the family room attic and sealing attic and basement rim joists. If he does any work for me he will re-do the door blower test and I can check the fresh air in-take at that point.

I'm still not clear why phbsales reccomends putting the supply on the plenum, when you add a fresh air in-take. Even if you have a lot of leakage the basement should not be under any more negative pressure than not having the fresh air intake in the first place. Please correct me if I am missing something.
Key1

hearthman
05-09-2009, 05:23 PM
Seal and insulate the top of the thermal envelope. Since you had IR thermography in conjunction with a blower door test, you are ahead of the game in being able to correct 'hidden' bypasses. Pay close attention to the barn doors such as attic stair hatches and 'can'-type ceiling lights. Cans should be ICAT or Insulation Contact Air Tight rated and caulked to the ceiling with UL181-A/B-FX duct sealing mastic. Attic stairs/ hatch should have a tight fitting weatherstripping with the R level for your region. Ensure all penetrations to the attic are sealed such as pipes and wiring.

Seal the ducts to ~7% per Duct Blaster. Ensure the combustion chamber is sealed from the AHU plenum. If there is a filter slot, it should have a tight seal with a microswitch interlock.

Conduct Worst Case Depressurization/ Draft Interference Test. Then conduct combustion analysis. Make adjustments as needed for ESP, delta t, etc. Re-test as necessary. This is where once you have corrected the upper envelope and ducts and still get CAZ depressurization, you must consider either recirculating warm supply air back into the CAZ or provide powered tempered outdoor MUA. The supply grille is the down and dirty approach while the outdoor air costs more but will improve IAQ. Passive MUA sucks figuratively but not literally.

As for CAZ depressurization, you can use the micromanometer as DavidR described to put a number on it in Pascals but you can also use a chemical smoke puffer to demonstrate airflows.

HTH,
Hearthman

key1cc
05-09-2009, 08:20 PM
Seal and insulate the top of the thermal envelope. Since you had IR thermography in conjunction with a blower door test, you are ahead of the game in being able to correct 'hidden' bypasses. Pay close attention to the barn doors such as attic stair hatches and 'can'-type ceiling lights. Cans should be ICAT or Insulation Contact Air Tight rated and caulked to the ceiling with UL181-A/B-FX duct sealing mastic. Attic stairs/ hatch should have a tight fitting weatherstripping with the R level for your region. Ensure all penetrations to the attic are sealed such as pipes and wiring.

Seal the ducts to ~7% per Duct Blaster. Ensure the combustion chamber is sealed from the AHU plenum. If there is a filter slot, it should have a tight seal with a microswitch interlock.

Conduct Worst Case Depressurization/ Draft Interference Test. Then conduct combustion analysis. Make adjustments as needed for ESP, delta t, etc. Re-test as necessary. This is where once you have corrected the upper envelope and ducts and still get CAZ depressurization, you must consider either recirculating warm supply air back into the CAZ or provide powered tempered outdoor MUA. The supply grille is the down and dirty approach while the outdoor air costs more but will improve IAQ. Passive MUA sucks figuratively but not literally.

As for CAZ depressurization, you can use the micromanometer as DavidR described to put a number on it in Pascals but you can also use a chemical smoke puffer to demonstrate airflows.

HTH,
Hearthman

Great to see more and more knowledgable people chiming in. Your advice is appreciated and is consistant with what I have learned.....Focus efforts on the top of the thermal envelope as well as on any "barn door" opportunities.

Worst case depressurization was performed in my basement (which is my combustion appliance zone or CAZ as you called it:)) with all bathroom and kitchen exhaust fans on full blast as well as the dryer running. I believe my number was between -2 and -3 pascals I have to wait for the final report to be sure, but the tech said it was fine.

Thanks for further elaborating on why a grill on the plenum could be neccessary. Now it makes perfect sense. Protect the CAZ at all cost from backdraft :cool: . Hmmm, now I have a dilema as I tighten my envelope. My fresh air intake will only run when the blower fan is running. It is more than adequate in providing the Make up Air (or if you prefer MUA) but it will not operate between conditioning cycles unless I leave the blower fan on 24/7. It is not independently mechanically driven. Since the hot water heater could demand heat between conditioning cycles I could be vulnerable to back draft.

Oh, by the way....I did not have IR thermography done. The tech simply identified the infiltration areas with a smoke puffer and by hand.

Key1

key1cc
05-09-2009, 09:31 PM
Your blower door data does not give you any useful information by itself. You need to correlate it with the volume and floor area of the house. This will tell you your ACH50 and can be converted to ACHnat to show how leaky the house is. You will most likely get these numbers in your report.

Not being a patient man...I could not wait for my report so I ran the numbers myself :).

As stated earlier the calculated minimum CFM50 number is 2864 as done by the pro. I remeasured everything myself and re-ran the calculations and got a calculated minimum CFM50 of 2772 (which I figure is close enough since I spent some time to be as accurate as possible and I took into consideration the different ceiling height in the family room.) When I convert my minimum CFM50 number to ACH50 (air changes per hour at -50 pascals) I get 5.4. This is the minimum recomended ACH50 for my home. When I plug in the actual blower door CFM50 number of 3400 my actual ACH50 number becomes 6.6 which converts to 0.33 ACHnat. I interpret this as meaning my home naturally exchanges the total volume of air once every 3 hours. I do not know if that is good or bad for air quality or for efficiency in NJ. Any insight here would be much appreciated.
Thanks
Key1

energy star
05-09-2009, 09:49 PM
What was the temp outside when the test was done?
Are the basement walls painted?
What type of water heater do you have?
How is the water heater vented?
You have one heat source. The main trunk is in the basement?
Any duct in the attic?

I have been following and just thought I would ask some questions I thought about.

key1cc
05-09-2009, 10:10 PM
What was the temp outside when the test was done?
Are the basement walls painted?
What type of water heater do you have?
How is the water heater vented?
You have one heat source. The main trunk is in the basement?
Any duct in the attic?

I have been following and just thought I would ask some questions I thought about.

The outside temp was 74-77F
The basement is unfinished but the cinderblock walls are painted white. Why?
My water heater is the standard 9 year home depot type that vents up through the chimney (with liner) through open flue cone vent pipe into chimney liner. A CO, O2, CO2 and stack temp was done as well as a draft pressue check (-8.5 pascals I beleive).
I just have the XV95 gas furnace with 3 main trunks coming off the plenum all in the basement.
No ducts in the attic.

Key1

beenthere
05-09-2009, 10:21 PM
Is that .33 include the basement.

energy star
05-09-2009, 10:35 PM
Oval pipe through walls up to the second floor I assume? First floor supplies in wall or floor. Second floor supplies in walls? How is the return air handled on the second (top) floor? One in each room?
Was the flue for the water heater left on the entire blower door test?
Was the basement door sealed and the space taken out of the equation, or left open?

teddy bear
05-10-2009, 07:50 AM
No actual ACH50 number becomes 6.6 which converts to 0.33 ACHnat. I interpret this as meaning my home naturally exchanges the total volume of air once every 3 hours. I do not know if that is good or bad for air quality or for efficiency in NJ. Any insight here would be much appreciated.
Thanks
Key1
Excellent disscusion of a most critical issue of modern housing design. The air change rate is for an average winter day. Approx. 20^F, 7.5 mph wind. With higher winds and colder weather, more air change. The air change rate may double in 25 mph winds and -0^ F.
On the other end, the air change rate declines to near Zero in calm winds and neutral temperatures. House tightening is an expensive and time intensive challenge. Most experts consider tightening the home to the point of a having a minimal acceptable air change rate during the extreme weather conditions as reasonable. The need for fresh air is to purge indoor pollutants and renewing oxygen. .2 ach at average winter conditions or +.33 ach during the greater ventilating pressure generating weather. So a reasonable home has adequate fresh air during the colder weather and high winds/mild weather conditions. Your challenge is to provide adequate fresh air during occupancy the rest of the year at a reasonable investment/operating cost while maintaining healthy/comfortable indoor conditions. Some recommend avoiding fresh air during humid weather to avoid indoor humidity problems.

Keep in mind, that during non-occupied hours, high wind, and cold temperatures conditions, no supplemental fresh air ventilation is required. This could be +50-60% of the total hours of the year. During low outside moisture levels, humidification may be needed and during high outside moisture, dehumidification is required. High cooling loads provide the ideal <50%RH. Supplemental dehumidification is required in green grass climates. Over 25 years of evolution of trying to provide a manufactured, I have migrated to the ventilating dehumidfier as a basic device to meet needs of many homes. With the optimized controls to provide the fresh air when the home is occupied, blending, filtering, and dehumidifying/humidifying is possible. The addition of an ERV may be justified for extreme amounts of fresh air or extreme conditions. The interaction of these devices with the heating/cooling systems in the building and occupants needs are critical.
Regards TB

key1cc
05-10-2009, 09:48 AM
Is that .33 include the basement.

Yes the .33 ACHnat includes the basement. My basement door has about a 1 inch opening under the door so it is not sealed even when closed.....although the tech also did the blower door test with the basement door closed and I will crunch those numbers shortly.
Key1

beenthere
05-10-2009, 09:53 AM
Then besides sealing that door sill, you'll also want to have all of your switches and recepts on the inside walls sealed.

Do you have a nat draft water heater?

hearthman
05-10-2009, 09:57 AM
Teddy makes a great point that all testing, no matter how comprehensive, is still just a snapshot in time. Stack effect is minimal in summer and pronounced in winter. Wind effect as Teddy noted. Operational conditions within the home..., etc.

To reiterate: passive MUA is very unreliable. ASHRAE did a study proving it. If you want Ventiation, your best bet may be a HRV or ERV. These guys can better discuss those options than me. Yes, you need to seal the thermal envelope and yes, you need to ventilate. Unless air is moving both in and out, you ain't ventilating.
BTW, the ASHRAE std. is 0.35 ACH as a min. ventilation rate and that is for people--not to ensure against backdrafting. Only powered MUA properly balanced can do that. Typically, these fans are wired with a slave switch, such as a current sensing switch to the two largest exhaust hogs in the home. Typically, this means the clothes dryer and kitchen hood. The new ASHRAE 62.2 now calls for powered MUA for ALL exhaust devices in new construction, though it is seldom done.
BTW, in order to qualify as a MUA grille, your door would need to be undercut a min. 3"!
HTH and glad to see someone who is educating themselves on this stuff.
Hearthman

key1cc
05-10-2009, 10:01 AM
Oval pipe through walls up to the second floor I assume? First floor supplies in wall or floor. Second floor supplies in walls? How is the return air handled on the second (top) floor? One in each room?
Was the flue for the water heater left on the entire blower door test?
Was the basement door sealed and the space taken out of the equation, or left open?

The hot water heater exhaust pipe goes into the basement wall directly into the chimney liner which is in the chimey which ultimately exits on top or the 2nd story roof.

First and second floor have supplies in every room. some rooms have multiple supplies. All have the supplies on the wall about a foot from the floor. All have supplies on the exterior walls and the kitchen and family room have supplies on the interior walls as well as the exterior walls. 4 bedrooms are upstairs. All but one have returns. The returns are high on the wall near the ceiling. All interior doors were left open during the the first blower door test. Then the basement was closed and the number changed....I will calculate the door closed results after breakfast :). I am not aware of anyway to close the flue for the water heater?? It remained open throughout the test.
Key1

key1cc
05-10-2009, 10:16 AM
Excellent disscusion of a most critical issue of modern housing design...........
Keep in mind, that during non-occupied hours, high wind, and cold temperatures conditions, no supplemental fresh air ventilation is required.

My original plan was to have a Fresh air intake installed soley for the purpose of putting the house under positive pressure to keep the Tree pollen from infiltrating during the high tree pollen months of April and May. (The incoming air is directed through a Merv 10 5" media filter).

After participating in this thread, I think I am hearing the experts tell me I should have the fresh air intake ready to use at anytime that the conditions warrent eventhough it may cost me a little more to cool or heat it (mostly cool since it is not required in the winter). Especially since my home has already shown it can have an ACHnat of less than 0.35 which is the cutoff where ventallation is recomended.
Key1

key1cc
05-10-2009, 10:47 AM
Do you have a nat draft water heater?

Yes

key1cc
05-10-2009, 11:28 AM
The calculated minimum CFM50 number with the basement door closed is 2008 CFM. (Recall it was 2772 with the door opened.) When I convert the minimum CFM50 number to ACH50 (air changes per hour at -50 pascals) I get 5.4 which is the same minumum I got with the door open. This makes total sense since the minimum is the minumum whether the door is open or not.

Now for the actual numbers from the blower door test.
When I plug in the actual blower door CFM50 number of 2124 my actual ACH50 number becomes 5.7 which converts to 0.29 ACHnat. I interpret this as meaning my home naturally exchanges the total volume of air once every 3.5 hours. Recall when the basement door was open the house took less time (3 hours) for the air to natural exchange 1 time suggesting my basement is a leaky area.

Yep I will definatly seal where the bottom plate meets the upper foundation wall.

I am still a little uncertain of one more thing. Since the minimum ACH50 for my building is 5.4 which is the BAS (buildinga airflow standard) I've read that it is not recomended by "ASHRAE 62-89" that I install mechanical ventilation. It is only reccomended if my ACH50 is less than 5.4. or said another way less than 0.27 ACHnat. In one of these post I thought I read that mechanical ventilation is required if your value is less than 0.35 ACHnat?

Key1

davidr
05-10-2009, 04:16 PM
My water heater is the standard 9 year home depot type that vents up through the chimney (with liner) through open flue cone vent pipe into chimney liner. A CO, O2, CO2 and stack temp was done as well as a draft pressue check (-8.5 pascals I beleive).

This is why you need the supply register cut in the supply plenum that phbsales mentioned.
That area of the home needs to have a source of air for the water heater.

If you have supply registers in your basement then this is already being done.
Would be nice to know some pressure readings on that space with fans running, etc...

I'm guessing the fellow that did the testing only did a one time shot of the combustion readings or did he take several readings over the entire run cycle?

DGIO-Not
05-10-2009, 06:06 PM
This is why you need the supply register cut in the supply plenum that phbsales mentioned.
That area of the home needs to have a source of air for the water heater.

If you have supply registers in your basement then this is already being done.
Would be nice to know some pressure readings on that space with fans running, etc...

I'm guessing the fellow that did the testing only did a one time shot of the combustion readings or did he take several readings over the entire run cycle?

BPI Analyst Are required to establish worst case as well as analyze each CAZ. The only thing not included is stoking up a fire place to get that venting as well. (oh..and that whole house fan we are suppose to tell you to get rid of.)

DGIO-Not
05-10-2009, 06:23 PM
I am still a little uncertain of one more thing. Since the minimum ACH50 for my building is 5.4 which is the BAS (buildinga airflow standard) I've read that it is not recomended by "ASHRAE 62-89" that I install mechanical ventilation. It is only reccomended if my ACH50 is less than 5.4. or said another way less than 0.27 ACHnat. In one of these post I thought I read that mechanical ventilation is required if your value is less than 0.35 ACHnat?

Key1

ASHRAE 62-89: It is required when the measured CFM50 is less than 70% of BAS, it is recommended if between 70-100% of BAS

davidr
05-10-2009, 07:01 PM
BPI Analyst Are required to establish worst case as well as analyze each CAZ. The only thing not included is stoking up a fire place to get that venting as well. (oh..and that whole house fan we are suppose to tell you to get rid of.)

Not familiar with BPI testing protocol, do they require testing over the entire run cycle or just a one time set of readings?

DGIO-Not
05-10-2009, 07:46 PM
It really depends on observations in the differing CAZs, especially if get into a huge home. It is very helpful to have two persons monitoring and recording all the test equipment we have running. To answer your question: No, not a complete cycle. We are suppose to wait for steady state. If steady state does not happen before or at 10min, we are suppose to record measurements then fire all other connected appliances in CAZ recording all measurements (CO, Draft, spillage.)

The standards require that if at any time, an appliance fails under worst case, we perform the test again under natural conditions. And then we are required to confirm again and compare with worst case..this is for all CAZs not just the problem CAZ. If continues to fail, we have to tell them to have the situation repaired by a reputable HVAC contractor before we can continue the test. The Action Levels Chart in the Standard is actually very nicely done and they do have a NATE guru on their board so I can see why it works.

davidr
05-10-2009, 07:56 PM
It really depends on observations in the differing CAZs, especially if get into a huge home. It is very helpful to have two persons monitoring and recording all the test equipment we have running. To answer your question: No, not a complete cycle. We are suppose to wait for steady state. If steady state does not happen before or at 10min, we are suppose to record measurements then fire all other connected appliances in CAZ recording all measurements (CO, Draft, spillage.)

The standards require that if at any time, an appliance fails under worst case, we perform the test again under natural conditions. And then we are required to confirm again and compare with worst case..this is for all CAZs not just the problem CAZ. If continues to fail, we have to tell them to have the situation repaired by a reputable HVAC contractor before we can continue the test. The Action Levels Chart in the Standard is actually very nicely done and they do have a NATE guru on their board so I can see why it works.

There could be some serious issues being missed by doing the one point test.

When you are combustion testing the appliances is the blower door running at a set pressure to simulate worst case or are you only using the fans in the building?

TIA

DGIO-Not
05-10-2009, 08:25 PM
There could be some serious issues being missed by doing the one point test.

When you are combustion testing the appliances is the blower door running at a set pressure to simulate worst case or are you only using the fans in the building?

TIA

:-) Boy you are making me work for this! Okay, we set the house to winter time conditions, simulating worse case--all appliances working at same time. All exterior doors, windows, dampers closed. We then compare the pressure inside with outside. We then turn on all exhaust fans one by one recording pressure with each (including dryer.) We then close all interior doors for rooms that are not under negative pressure. Then turn on furnace or air handler fan. If that CAZ becomes more negative, we proceed. The blower door would only be used as a tool to simulate another event that could not be active at the time.

I have used the blower door as an addition. My favorite is in reverse to demonstrate to a home owner who rarely cooked but had the 600cfm vent hood without any additions, of why she needed to be mindful of manufacturer's recommendations for homes--and open a window! It was just a way of putting a safe, tangible number in front of her.

energy star
05-10-2009, 08:33 PM
I am totally psyched by this site, it's the best. The level of experience is second to none. But I'm having some problems with the level of formulation and number crunching going on.

I would like to dumb this down a bit. The OP was interested in saving money or wanted to see how tight his home was. I understand this and who wouldn't want t know.

I think, or rather feel the test is flawed and will give no exact information. It is extracting data and using that data in an extrapolation type of procedure to get an answer. This answer is elusive and can not be one that is a constant. The results will never be the same. Here is why I think this.

It was over 70 degrees when we tested the efficiency of the furnace. Is it not harder to heat air that is 10 degrees to 70, than it is to heat 70 degree to whatever (when its warm out). Point is, getting the efficiency of 95% or what was stated in the first post is not accurate if the ambient air is above 70. I also think the basement was not pulled out of the equation correctly (sealed). A duct blaster should have been used. The test, I feel should be conducted in two or three different seasons with different outside conditions to simulate a more accurate result. I could go on, but I won't. I just think I could roll off a list of of line items that were not done correctly that would result in false readings or data. If we want to find out how tight the house is, we need to close or seal ALL holes to the outside. Does he have gable vents? Does he have recessed lighting on the second floor? I know an interested party must start somewhere but the level of preparation to conduct a test is the common denominator that produces the result and if this is left up to a monetary commitment, (as he stated in post one, he spent 4hrs) The result will be inaccurate. Just my .02

Carnak
05-10-2009, 08:45 PM
Teddy makes a great point that all testing, no matter how comprehensive, is still just a snapshot in time. Stack effect is minimal in summer and pronounced in winter. Wind effect as Teddy noted. Operational conditions within the home..., etc.

To reiterate: passive MUA is very unreliable. ASHRAE did a study proving it. If you want Ventiation, your best bet may be a HRV or ERV. These guys can better discuss those options than me. Yes, you need to seal the thermal envelope and yes, you need to ventilate. Unless air is moving both in and out, you ain't ventilating.
BTW, the ASHRAE std. is 0.35 ACH as a min. ventilation rate and that is for people--not to ensure against backdrafting. Only powered MUA properly balanced can do that. Typically, these fans are wired with a slave switch, such as a current sensing switch to the two largest exhaust hogs in the home. Typically, this means the clothes dryer and kitchen hood. The new ASHRAE 62.2 now calls for powered MUA for ALL exhaust devices in new construction, though it is seldom done.
BTW, in order to qualify as a MUA grille, your door would need to be undercut a min. 3"!
HTH and glad to see someone who is educating themselves on this stuff.
Hearthman

Sometimes stacks invert, I have measured it myself.

If you feel you need the constant source of fresh air the HRV and ERV are your best choices with respect to energy efficiency. An HRV balanced and running at 0.35 ACH or even half that rate will make your house so dry in the dead of winter your lips will split open unless you add a humidifier. You ventialte to stop winter time window condensation then you humidify because it is too dry. I sort of prefer to ventilate on a rise in RH myself to keep the windows clear. I figure your windows tell you in the winter if you are getting enough air or not.

I would not be overly worried about intermittent exhausts like clothes dryers etc, unless it had an impact on venting of combustion products. When there are no combustion problems, the intermittent exhaust of the magnitude of a clothes dryer are not a big problem.

What can be problematic in really tight homes, and we are talking less than 0.1 ACH in winter, are Italian Stainless Steel Kitchen Hoods and Jenn Airs trying to pull 300, 600 or even 1200 CFM out of a house. For one, these appliances will sure let you know if your plumbing traps are primed.

300 CFM, I have seen a passive interlocked motorized damper work fine to allow make up air in -- 600 and 1200 CFM you are into the realm of a make up air fan and most likely an electric duct heater to temper the air up above freezing so you do not freeze water pipes in a basement.

I think a system that can do 0.3 to 0.35 ACh intermittently when needed is fine myself, but I tend to make stuff up as I go along.

You need a system to ventilate.

You need a system for combustion air, i prefer direct vent

You can also need a make up air system for the big exhausts.

If you need all three you need three systems. One system does not serve all.

energy star
05-10-2009, 09:00 PM
You need a system to ventilate.

You need a system for combustion air, i prefer direct vent

You can also need a make up air system for the big exhausts.

If you need all three you need three systems. One system does not serve all.

I think we all know this. But this thread is not about those parameters. Design conditions.

DGIO-Not
05-10-2009, 09:01 PM
I think, or rather feel the test is flawed and will give no exact information. It is extracting data and using that data in an extrapolation type of procedure to get an answer. This answer is elusive and can not be one that is a constant. The results will never be the same.

I whole heartedly agree and know where you are going. However, HVAC is my profession and we extrapolate a lot (cannot have best conditions each and every time trying to alleviate a problem.) Ode to the labratory where we can set the ideal! :D

To borrow from another, we seek to be accurate, not precise.

Carnak
05-10-2009, 09:02 PM
stack effect, hot air rises goes to the top floor , pressurizes ceiling and walls windows above the neutral plane. So air escapes high and the lower area goes negative. Then theoretically all the infiltrating air comes in around basement window frames etc, other places below the neutrral plane.

What other forces can also make a basement negative?

How about when you use joist lining or panning as some call it to make your return branch ducts. Probably half the return air the furnace draws in is in the basement and it is unintentional. Leaks right on the unit, and from those floor joists. Maybe the return system even pulls stuff down from an attic.

So this kind of depressurized basement or wall cavity leaks do not care if it is summer or winter. You get a pressure differential year round.

I would also say in the cooling climates, where they run all the ducts in the attic, that most of the infiltration is caused by duct leaks and this again does not care if it is summer or winter.

And when you have all your supplies and returns in the ceiling, cold air falls to the floor and pressurizes low. This is an inverted stack. Cold air falling down from the second floor to the ground floor will also suck air out of an attic and in backwards through exhaust fans

Carnak
05-10-2009, 09:08 PM
I think we all know this. But this thread is not about those parameters. Design conditions.So what is it exactly about now, dividing ACH 50 numbers by 20 to come up with my house will leak at 0.33 ACH?

Splain it to me Lucy

energy star
05-10-2009, 09:18 PM
So what is it exactly about now, dividing ACH 50 numbers by 20 to come up with my house will leak at 0.33 ACH?

Splain it to me Lucy

I simply saying you are tossing more parameters into this equation. If we have a "Jenn-air" with a killer exhaust we know a make up air system will be necessary. We realize or rather I realize what you are saying, but what you have described is not in the OP original post. It appears that it is justification for more number crunching and abbreviation in an equation that does not merit it.

Carnak
05-10-2009, 09:22 PM
the original post was about combustion numbers at low fire and high fire. Perhaps you would like to moderate and nudge everyone on this thread back to this topic?

energy star
05-10-2009, 09:26 PM
Yes and post 60 will tell you why it is I posted.

Carnak
05-10-2009, 09:28 PM
okay how about this. A blower door is good for finding where your leaks are, but is basically as useful as tits on a bull when trying to figure out the leak rate of a tight home?

energy star
05-10-2009, 09:41 PM
Yo, dude chill out, The test was not done in a fashion that would produce an accurate result. It was done in a manner to appease the home owner in a VERY basic manner. He has a leak at his hot water heater flue. He has a leak at his basement door. and who knows where else. The furnace he has, I believe has a combustion air intake. So he has a water heater in his """""CAZ zone""""" the basement leakage and sq footage covers that. You really think this homeowner needs to heat or cool outside air for ventilating? That would negate the savings from all this high efficiency equipment and effect the payback time and the money spent on the initial investment in the first place.

DGIO-Not
05-10-2009, 09:55 PM
Actually guys, and please do not flame me for this, this is a new thread from a post of whether the HO would add a Hepa filter to aid in allergen control. The bigger picture is that as a consensus, building science won out in fixing an IAQ problem. Because the HO is a very active, knowledgable, and very much part of this process, we are able to take things to a very different level. Makes us all smarter in the end, doesn't it?

Carnak
05-10-2009, 09:58 PM
I am not trying to be the thought police here so I do not really need to chill.

You either directly or indirectly heat/cool ventilation air.

Now if you are worried about a water heater, then perhaps you add a combustion air system for it, but then again you said you already knew this and I was being off topic by mentioning it.

Passive intakes not a guarantee, there are powered intakes for this purpose. A better choice would be to go with a power vented water heater since he already has a condensing furnace.

What colour should he paint his basement?

Carnak
05-10-2009, 10:06 PM
I simply saying you are tossing more parameters into this equation. If we have a "Jenn-air" with a killer exhaust we know a make up air system will be necessary. We realize or rather I realize what you are saying, but what you have described is not in the OP original post. It appears that it is justification for more number crunching and abbreviation in an equation that does not merit it.

usually when you quote someone, it implies you are talking to the person you quoted, or you wish to discuss something the person you quoted just wrote.

Sort of like you did when you quoted me here. I do not really get why something I was saying to hearthman has your panities in a knot.

So I am sorry if what I say is not what you want to discuss, but you are free to ignore me. Or you can buy the site and maybe control me herr furhur.

energy star
05-10-2009, 10:10 PM
Funny with the basement color. I mean really thats very funny, I'm laughing also. But you of all people "negative pressure sucks" would understand. You can pull a vacuum on an entire basement (John Tooley). But I won't get into to that. A power vented water heater would be a better choice.

key1cc
05-10-2009, 10:12 PM
WOW!!!

You gotta love this site..

:)

Key1

key1cc
05-10-2009, 10:44 PM
I am all for helping to increase the knowledge base of the industry if I could.
Let's say we take this to the next level.

For those on the sidelines that are still a little unclear, I am attaching what I believe is a key (no pun intended) document to the entire discusion. It is how I learned to calculate my own numbers and in conjuction with the posts in this thread, have given me the insight I needed to make some informed decisions. It is 17 pages but well worth the reading to help further your understanding.

Key

stvc
05-11-2009, 12:46 AM
Not being a patient man...I could not wait for my report so I ran the numbers myself :).

As stated earlier the calculated minimum CFM50 number is 2864 as done by the pro. I remeasured everything myself and re-ran the calculations and got a calculated minimum CFM50 of 2772 (which I figure is close enough since I spent some time to be as accurate as possible and I took into consideration the different ceiling height in the family room.) When I convert my minimum CFM50 number to ACH50 (air changes per hour at -50 pascals) I get 5.4. This is the minimum recomended ACH50 for my home. When I plug in the actual blower door CFM50 number of 3400 my actual ACH50 number becomes 6.6 which converts to 0.33 ACHnat. I interpret this as meaning my home naturally exchanges the total volume of air once every 3 hours. I do not know if that is good or bad for air quality or for efficiency in NJ. Any insight here would be much appreciated.
Thanks
Key1

I think you may have miscalculated somehow. If you use the LBL method [which is considered more accurate] to calculate ACHn [natural air exchanges per hour] the formula is ACHn=CFM50 * 60 / (n*V)
So the n-factor for 2 story above grade normally shielded in NJ is 14.8
Volume would be 4100sqf x 8’ = 32800, I used 8’ but know you said something about a vaulted ceiling. I also included the basement since the basement walls are almost always the pressure boundary.
I come up with your existing ACHn at .42, if your goal is .35 which is a good recommended goal your CFM50 would be 2832, pretty close to the number you have been given.

key1cc
05-11-2009, 08:02 AM
I think you may have miscalculated somehow. If you use the LBL method [which is considered more accurate] to calculate ACHn [natural air exchanges per hour] the formula is ACHn=CFM50 * 60 / (n*V)
So the n-factor for 2 story above grade normally shielded in NJ is 14.8
Volume would be 4100sqf x 8’ = 32800, I used 8’ but know you said something about a vaulted ceiling. I also included the basement since the basement walls are almost always the pressure boundary.
I come up with your existing ACHn at .42, if your goal is .35 which is a good recommended goal your CFM50 would be 2832, pretty close to the number you have been given.

It is possible that you may be correct but as my teacher alway said....show your math. Here is mine. The actual more precisely measured sq feet including basement is 3745sqf. Considering the one vaulted ceiling the total cubic feet is 30918 CF (The 4100sqf you used was the analysts estimate which was based on measuring the basement and making assumptions for the upper floors. I actually measured the upper floors to get the exact values although both are so close they come out to the same value in the end). Also according to page 5 of the the BPI document that I attached in my previous post the N-factor for NJ is the same as that for NY which is 15.4 not 14.8. The measured blower door CFM50 was 3400 with basement included. Plug those numbers in and you get a ACH50 of 3400x60/30918 = 6.6. Divide that by 20 for your ACHnat and you get an existing ACHnat of 0.33.
According to page 4 of the document I attached in the previous post, I interpreted that the N-factor is only considered when calculating the BAS minimum CFM50 not the actual measured value of your home. It is a standard not a measurement. (That part I am not 100% clear on).

Lets look at the LBL calculation you referenced.
The difference is that I would take my numbers and include the N-factor:
3400x60/30918x15.4 = 0.42

Which is the ACHnat you referenced.

That value has different implications because it suggest that I do not require mechanical ventilation whereas the 0.33 implied that I did.

Hmmmm, any BPI analyst out there know for sure if the n-factor is considered on the actual measurement? Or just on the standard.

I think STVC is actually correct as it makes more sense to me and a few of us may have just reached a new level of enlightenment :)

I love quoting the one pro here who's tag line is

"we never stop learning until we are dead"

Key1

hearthman
05-11-2009, 09:27 AM
I have not taken the BPI course nor read fullly through its protocols but based upon the document presented, I do have a few observations:
ASHRAE 62.2-89> There is now a 2007 Revision of this document, which has been revised every three years. Not sure why they are basing this on a very old revision of this std.
UL 2034 CO alarms> Has been well discussed the flaws with these alarms. Do not offer adequate protection on the low end, as stated on their packaging and are very unreliable. The BPI protocol calls to halt the test if >35ppm CO but you would die first if you were relying on one of these alarms to protect you. Should use unlisted low level CO monitors: CO Experts or NSI 3K
Worst Case Conditions> very disjointed but appears to turn of all appliances at one time then point test. A worst case test is just that. You won't know when you're reached it until you turn on all exhausts and mechanical ventilation individually then collectively. Ususually, when I encounter houses with multiple forced air systems, one actually improves the CAZ pressure profile while others hinder. For instance, in a house with 3 systems, you are running them individually then collectively. This means you draw up a matrix to cover the combinations
Spillage guidelines> It says to test for spillage but does not reference how this is determined. For instance, it discusses using chemical smoke or mirror to test for spillage at a draft hood??? Now that's quantitative and reliable (not). At what point? It talks about spillage after one minute but the ANSI Stds. allow spillage for up to 10 minutes. Few water heaters cycle that long. That means it can legally backdraft for an entire firing cycle.
This test requires closing the fireplace damper> A burning open hearth can exhaust 400-600cfm up the chimney and is probably the most sensitive combustion appliance for spillage, yet it is not being tested? How do you know the WH won't backdraft when the Fp is burning under Worst Case? Will the Fp spill smoke under Worst Case?

Still, I feel they are on the right track. Over time, we learn more. That's why we have code and std. revisions. It ain't perfect but we do need to be alert to defects in our logic and fight to ensure we are not making false assumptions in our test methodologies.
Hearthman

Carnak
05-11-2009, 10:19 AM
It is possible that you may be correct but as my teacher alway said....show your math. Here is mine. The actual more precisely measured sq feet including basement is 3745sqf. Considering the one vaulted ceiling the total cubic feet is 30918 CF (The 4100sqf you used was the analysts estimate which was based on measuring the basement and making assumptions for the upper floors. I actually measured the upper floors to get the exact values although both are so close they come out to the same value in the end). Also according to page 5 of the the BPI document that I attached in my previous post the N-factor for NJ is the same as that for NY which is 15.4 not 14.8. The measured blower door CFM50 was 3400 with basement included. Plug those numbers in and you get a ACH50 of 3400x60/30918 = 6.6. Divide that by 20 for your ACHnat and you get an existing ACHnat of 0.33.
According to page 4 of the document I attached in the previous post, I interpreted that the N-factor is only considered when calculating the BAS minimum CFM50 not the actual measured value of your home. It is a standard not a measurement. (That part I am not 100% clear on).

Lets look at the LBL calculation you referenced.
The difference is that I would take my numbers and include the N-factor:
3400x60/30918x15.4 = 0.42

Which is the ACHnat you referenced.

That value has different implications because it suggest that I do not require mechanical ventilation whereas the 0.33 implied that I did.

Hmmmm, any BPI analyst out there know for sure if the n-factor is considered on the actual measurement? Or just on the standard.

I think STVC is actually correct as it makes more sense to me and a few of us may have just reached a new level of enlightenment :)

I love quoting the one pro here who's tag line is

"we never stop learning until we are dead"

Key1the calculation procedure based on a blower door test has evolved somewhat from dividing the ACH50 by a fudge factor of 17 to 20.

The net result from the blower door test, besides locating where your leaks are is to give you a conservative infiltration value that if you use it to size your heating equipment, you will not be undersizing your heating equipment.

Now I brag about my own home but with normal winds maybe I leak 5 CFM. Scale that up by a factor of 20 and that is 100 CFM, which is probably 55% what my clothes dryer exhausts. So what I have noticed is my ears do not pop like I have instantly been depressurized by 50 Pa when my wife dries a load of clothes.

skizot
05-11-2009, 10:32 AM
The calculated minimum CFM50 number with the basement door closed is 2008 CFM. (Recall it was 2772 with the door opened.) When I convert the minimum CFM50 number to ACH50 (air changes per hour at -50 pascals) I get 5.4 which is the same minumum I got with the door open. This makes total sense since the minimum is the minumum whether the door is open or not.

Now for the actual numbers from the blower door test.
When I plug in the actual blower door CFM50 number of 2124 my actual ACH50 number becomes 5.7 which converts to 0.29 ACHnat. I interpret this as meaning my home naturally exchanges the total volume of air once every 3.5 hours. Recall when the basement door was open the house took less time (3 hours) for the air to natural exchange 1 time suggesting my basement is a leaky area.

Yep I will definatly seal where the bottom plate meets the upper foundation wall.

I am still a little uncertain of one more thing. Since the minimum ACH50 for my building is 5.4 which is the BAS (buildinga airflow standard) I've read that it is not recomended by "ASHRAE 62-89" that I install mechanical ventilation. It is only reccomended if my ACH50 is less than 5.4. or said another way less than 0.27 ACHnat. In one of these post I thought I read that mechanical ventilation is required if your value is less than 0.35 ACHnat?

Key1

The old rule of dividing by 20 is pretty inaccurate. You should be using the LBL method (N-correlation factor). The good energy auditors (those with NCI and BPI training) will use this method to calculate the Natural ACH for you. From re-reading your last post, it looks like you've got the N-correlation factor. According to what you've posted, that yields:

ACH50 = (3400 CFM * 60) / 30918 ft^3 = 6.598
Natural ACH = 6.598 / 15.4 = 0.428

You should be using the N-correlation factor when calculating Natural ACH. The reason this method was created was to account for local conditions (wind shielding, structure height, etc.). The ACH50/20 rule does not take local conditions into consideration; it is just an old means of approximating Natural ACH.

The N-factor that BPI has listed for New York is interesting though. I'd be really curious as to how they got that exact number, because the wind shielding correction factor is still a range. For New York, it's 17-20. So, after calculation (using H = 0.8), that would give you a range for N, being 13.6 to 16.0 (resulting in a Natural ACH range for your home of 0.412 to 0.485). Maybe the 17 is for the less densely-populated areas of New York (some residential neighborhoods) and the 20 is for being closer to the heart of the city (lots of buildings to block the wind)?

Jim Davis
05-11-2009, 02:54 PM
Now thats the kind of feedback I was hoping for.
When I "clocked" my gas meter ( by turning off all gas appliances and only letting the furnace run), I realized my manifold gas pressure could use adjusting because I only clocked 60,000 btu incoming on low fire and 89,000 btu incoming on high fire. My capacaity should be 65k and 100k incoming and 95k and 61750 k out.

Is it worthwhile to have the manifold pressures tweaked up a bit?

Key1

The fact that Trane specs sheets list smaller orifices than their firing rate would account for what you are measuring. Actually you are getting more than most.

As far as efficiency there are many factors to consider but the simplest are the following:

1% O2 = 1% efficiency loss
10 degrees(condensing furnace) above ambient = 1% efficiency loss

Natural gas combustion produces 14% H20 or latent heat. Condensing furnaces recover 80% of this.

Therefore 100% minus 8% = 92% minus 2%(T) = 90% minus 3%(H2) = 87%.
This would be the maximum theoretical efficiency with these numbers. But then that is only 87% of the usable btus that are available, not the theoretical value of the fuel.

Fuel only creates 100% usable energy at stoichiometric combustion or 0% excess air or O2 or a flame temperture of 3600 degrees. At 8% O2 the flame temperature is only around 2600 degrees which is less btus available for transfer. 80% of the air supplied to a burner is nitrogen which steals or absorbs btus and makes them unavailable for transfer.

Radiant energy of the flame is supposed to provide 60% of our total heat transfer. A flame that is cooler and smaller will radiate a considerably smaller amount of heat to the heat exchanger surface.

It is ashame that most think flue temperature represents only heat transfer.
The efficiency calculations that are used assumes maximum flame temperature(3600 degrees) is attained 100% of the time.

Just a quick explanation, and yes low-fire is rarely near 50% efficiency.

stvc
05-11-2009, 02:59 PM
The old rule of dividing by 20 is pretty inaccurate. You should be using the LBL method (N-correlation factor). The good energy auditors (those with NCI and BPI training) will use this method to calculate the Natural ACH for you. From re-reading your last post, it looks like you've got the N-correlation factor. According to what you've posted, that yields:

ACH50 = (3400 CFM * 60) / 30918 ft^3 = 6.598
Natural ACH = 6.598 / 15.4 = 0.428

You should be using the N-correlation factor when calculating Natural ACH. The reason this method was created was to account for local conditions (wind shielding, structure height, etc.). The ACH50/20 rule does not take local conditions into consideration; it is just an old means of approximating Natural ACH.

The N-factor that BPI has listed for New York is interesting though. I'd be really curious as to how they got that exact number, because the wind shielding correction factor is still a range. For New York, it's 17-20. So, after calculation (using H = 0.8), that would give you a range for N, being 13.6 to 16.0 (resulting in a Natural ACH range for your home of 0.412 to 0.485). Maybe the 17 is for the less densely-populated areas of New York (some residential neighborhoods) and the 20 is for being closer to the heart of the city (lots of buildings to block the wind)?

I thought that chart was strange too, the only one I have ever seen or used looks like this so you choose the shielding level. Maybe outdated?
This is zone 2, NJ according to my resources.

Number of Stories: 1 1.5 2 3
Well-Shielded 22.2 20 17.8 15.5
Normal 18.5 16.7 14.8 13
Exposed 16.7 15 13.3 11.7

So I come up with ACHnat=CFM50 * 60 / (n*V)

3400*60/(14.8*30918) = .45 ACHn if it is normally shielded, that of course is the auditors opinion and may vary.

davidr
05-11-2009, 04:04 PM
Watch the N factors, wind shielding, and other items that go into those calculations.
Lot's of assumptions being made behind those numbers.

Ten different blower door operators will normally come up with ten different sets of numbers.

energy star
05-11-2009, 04:55 PM
key1cc do you intend on posting the final report?

key1cc
05-11-2009, 05:51 PM
The fact that Trane specs sheets list smaller orifices than their firing rate would account for what you are measuring. Actually you are getting more than most.

As far as efficiency there are many factors to consider but the simplest are the following:

1% O2 = 1% efficiency loss
10 degrees(condensing furnace) above ambient = 1% efficiency loss

Natural gas combustion produces 14% H20 or latent heat. Condensing furnaces recover 80% of this.

Therefore 100% minus 8% = 92% minus 2%(T) = 90% minus 3%(H2) = 87%.
This would be the maximum theoretical efficiency with these numbers. But then that is only 87% of the usable btus that are available, not the theoretical value of the fuel.

Fuel only creates 100% usable energy at stoichiometric combustion or 0% excess air or O2 or a flame temperture of 3600 degrees. At 8% O2 the flame temperature is only around 2600 degrees which is less btus available for transfer. 80% of the air supplied to a burner is nitrogen which steals or absorbs btus and makes them unavailable for transfer.

Radiant energy of the flame is supposed to provide 60% of our total heat transfer. A flame that is cooler and smaller will radiate a considerably smaller amount of heat to the heat exchanger surface.

It is ashame that most think flue temperature represents only heat transfer.
The efficiency calculations that are used assumes maximum flame temperature(3600 degrees) is attained 100% of the time.

Just a quick explanation, and yes low-fire is rarely near 50% efficiency.

Thanks Jim for the words of wisdom. There are some on this site that you will never convince that low fire is typically below 50% efficiency. I guess you will have to agree to disagree :)

What camp am I in? I own a 2 stage furnace locked in 1st stage due to high static. I have no choice but to hope 1st stage is efficient....until I make it over to your course one day and get converted ;)

Key1

key1cc
05-11-2009, 05:57 PM
Watch the N factors, wind shielding, and other items that go into those calculations.
Lot's of assumptions being made behind those numbers.

Ten different blower door operators will normally come up with ten different sets of numbers.

My direction is now clear as mud :).

I will seal the house reasonably tight, control the infiltration level and direction (with positive pressure filtered fresh air), provide make up air for CAZ's, do seasonal assessments, and hope for the best.

Key1

key1cc
05-11-2009, 06:00 PM
key1cc do you intend on posting the final report?

For those that are familiar with my threads.... they know that I am a data man.......yes of course I will post the final findings.

Key1

skizot
05-11-2009, 06:12 PM
Watch the N factors, wind shielding, and other items that go into those calculations.
Lot's of assumptions being made behind those numbers.

Ten different blower door operators will normally come up with ten different sets of numbers.

Right, but they should not differ wildly. The difference between 0.33 Natural ACH and 0.428 Natural ACH is over 23%; that's a lot of difference in infiltration.

Carnak
05-11-2009, 06:29 PM
.until I make it over to your course one day and get converted ;)

Key1Don't let him circumsize you
Shaalom

Jim Davis
05-12-2009, 09:59 AM
For those that are familiar with my threads.... they know that I am a data man.......yes of course I will post the final findings.

Key1

Finding out what actual airflow you have and Delta T gives a good indication of actual heat transfer. No measurement is exact and the actual btus in the gas is unknown or approximate, but we can tell how many btus you are delivering per cu. ft. of gas.

At least your low fire O2 reading is in a better range than most. Can be lowered closer to 6% as long as CO stays below 100ppm and is stable.

90% furnaces use 150cfm per 10,000 btus of input. So 975cfm to 1000cfm in low fire would be close. This has to be determined by checking static pressure. I am guessing that your Delta T is less than 40 degrees if your cfm is correct. Remember the flue temperature represents the temperature of the secondary heat exchanger and if it is only 90 degrees it can't add much heat to 74 degree air.

Remember the size of the flame and the temperature of the flame determine how hot the heat exchanger gets. It is no different than sitting next to a campfire and expecting to stay just as warm as the fire gets smaller.

Carnak
05-12-2009, 12:03 PM
but we can tell how many btus you are delivering per cu. ft. of gas.

That sounds like a really good thing to know.

And it is only possible because in this situation the homeowner clocked it

Why not get your students to do the same after they supertuned it to your protocols?

You work for an outfit that prides itself on statistics, should be able to have a national trend develop of you vs all your nay sayers.

key1cc
05-12-2009, 12:11 PM
Finding out what actual airflow you have and Delta T gives a good indication of actual heat transfer. No measurement is exact and the actual btus in the gas is unknown or approximate, but we can tell how many btus you are delivering per cu. ft. of gas.

At least your low fire O2 reading is in a better range than most. Can be lowered closer to 6% as long as CO stays below 100ppm and is stable.

90% furnaces use 150cfm per 10,000 btus of input. So 975cfm to 1000cfm in low fire would be close. This has to be determined by checking static pressure. I am guessing that your Delta T is less than 40 degrees if your cfm is correct. Remember the flue temperature represents the temperature of the secondary heat exchanger and if it is only 90 degrees it can't add much heat to 74 degree air.

Remember the size of the flame and the temperature of the flame determine how hot the heat exchanger gets. It is no different than sitting next to a campfire and expecting to stay just as warm as the fire gets smaller.

I am expecting the official report hopefully by this weekend. Also during the weekend I will remeasure my static pressure with the fresh air intake and small 10x6 plenum register installed. Additionally I will recheck my temp rise (this time with the humidifier damper closed :rolleyes: Thanks BT).... I will also reclock my gas meter to see if it has changed. All at both low and high fire. The utility company has already provided me a "Heat Value" number for my incoming gas.
Additionally, I have the tools to make manifold gas adjustments if I need to go closer to the trane max targets of 1.7" for low fire and 3.5" for high fire.

I will post the findings for comment :)

Key1

energy star
05-12-2009, 01:42 PM
I know you have read your manual probably 300 times, I have a two stage gas valve also. I thought the pressures were higher. I just can't remember. So I'll say ,ok.

key1cc
05-12-2009, 02:04 PM
I know you have read your manual probably 300 times, I have a two stage gas valve also. I thought the pressures were higher. I just can't remember. So I'll say ,ok.
The manifold gas pressures I listed are for natural gas. Propane is different.
Key1

energy star
05-12-2009, 02:12 PM
The manifold gas pressures I listed are for natural gas. Propane is different.
Key1

I know. I just thought they were higher, my mistake. :)

Wild
05-12-2009, 08:51 PM
Here are the numbers for 1st stage:
Stack temp = 90
O2 = 8.4
CO2= 7.1
ambient temp = 72
CO= 5 ppm
Efficiency = 98.3

Here are the stage 2 numbers
Stack temp = 105
O2 = 8.3
CO2 = 7.2
ambient = 74
CO= 4 ppm
efficiency = 95.0

What was the gas pressure in low and high fire?

I’m finding your combustion readings very hard to believe. Looks to me like the readings were taken while the furnace was in the same stage.

Wild
05-12-2009, 09:00 PM
Additionally, I have the tools to make manifold gas adjustments if I need to go closer to the trane max tagets of 1.7" for low fire and 3.5" for high fire.

To be more specific I find it hard to believe that the furnace manifold gas pressure went from 1.7 inches to 3.5 inches with the O2 pretty much staying the same and the CO going down 1 ppm.

key1cc
05-12-2009, 09:45 PM
What was the gas pressure in low and high fire?

I’m finding your combustion readings very hard to believe. Looks to me like the readings were taken while the furnace was in the same stage.

I will mention that to the BPI analyst that performed the test when he comes back with his reccomendations and my final report.

I know for a fact they were taken in 1st and 2nd stage since I checked the static pressure while in first stage and got a reading of 0.43. I went up stairs and cut the heat up 10 degrees above ambient. We both heard it go into 2nd stage and I checked the static pressure to verify (~0.9 ESP).

But like I said I will mention it to him.

To be more specific I find it hard to believe that the furnace manifold gas pressure went from 1.7 inches to 3.5 inches with the O2 pretty much staying the same and the CO going down 1 ppm.

The 1.7 and the 3.5 inches are Trane specs.maximum target pressure settings. They are not my pressure settings. My manifold pressure settings were never checked by anyone (not even during installation) so I have no idea what they are. I will likely be checking them for the first time myself if warrented. I do have a Fieldpiece manometer that can be used for the task.

Key1

Wild
05-12-2009, 10:09 PM
If he comes back and has his analyzer maybe you could have him test the furnace again. Then watch the CO and O2 readings as it goes through the heating cycle and into second stage. And have the gas pressure checked at the same time. If you see the same numbers as you posted I’d be surprised.

This was a State sponsored energy audit and they probably endorse 2 stage furnaces and other high efficiency equipment. Could be he fudged the numbers to make it look like the first stage was more efficient. I don’t know, just saying those numbers don’t look right to me and I use my combustion analyzer all the time in the heating season.

energy star
05-12-2009, 10:13 PM
What Fieldpiece manometer model did you buy? Dual port?

key1cc
05-12-2009, 10:14 PM
If he comes back and has his analyzer maybe you could have him test the furnace again. Then watch the CO and O2 readings as it goes through the heating cycle and into second stage. And have the gas pressure checked at the same time. If you see the same numbers as you posted I’d be surprised.

This was a State sponsored energy audit and they probably endorse 2 stage furnaces and other high efficiency equipment. Could be he fudged the numbers to make it look like the first stage was more efficient. I don’t know, just saying those numbers don’t look right to me and I use my combustion analyzer all the time in the heating season.

Will do.

Thanks for the insight.

That is one of the reasons I started the thread (to get insight)

What should I expect to see as I watch the numbers? The Oxygen go down and the CO go up as it goes from 1st to 2nd stage?

Key1

key1cc
05-12-2009, 10:23 PM
What Fieldpiece manometer model did you buy? Dual port?

I've had the SDMN5 for several months and my Dwyer Gauge for almost a year. Both are dual port. Neither are as high tech as the Analyst's DG700...but they get the job done.
Key1

Wild
05-12-2009, 10:48 PM
What should I expect to see as I watch the numbers? The Oxygen go down and the CO go up as it goes from 1st to 2nd stage?
Yeah, that's what happens when you increase the gas. But then the readings should stabilize, not continue to rise or fall. I doubt he'll test again for you though.

energy star
05-12-2009, 11:12 PM
I have the DG700 (came with my duct blaster). When you check the pressure on a two stage gas valve the instructions in your equipment manual are very specific. Have fun!

beenthere
05-12-2009, 11:14 PM
As technical as this thread is getting on checking gas pressure.

Soon have to close the thread.

energy star
05-12-2009, 11:24 PM
Sorry about that! No more gas business from me. I would like it left open to see the report. But I guess he could start a new thread.

Jim Davis
05-13-2009, 09:00 AM
To be more specific I find it hard to believe that the furnace manifold gas pressure went from 1.7 inches to 3.5 inches with the O2 pretty much staying the same and the CO going down 1 ppm.

It is not the norm but it is possible. The inducer controls how much air goes through the heat exchanger. If the inducer speed is really low in low fire then it is possible to get the same O2 readings with either gas pressure. The flue temperature indicates 2 different firing rates.

Carnak
05-15-2009, 07:59 AM
interesting enough, some power burners with a high turn down ramp the combustion blower speed down, but as they turn the burner down to minimum, they actually ramp up the combustion blower. The reason for it is to reduce condensation on low fire.

Same smart guys who do this also have a condensate drain on their HX's, even though it is not designed as a condensing furnace

key1cc
05-15-2009, 11:07 PM
I am expecting the official report hopefully by this weekend. Also during the weekend I will remeasure my static pressure with the fresh air intake and small 10x6 plenum register installed. Additionally I will recheck my temp rise (this time with the humidifier damper closed :rolleyes: Thanks BT).... I will also reclock my gas meter to see if it has changed. All at both low and high fire. The utility company has already provided me a "Heat Value" number for my incoming gas.
Additionally, I have the tools to make manifold gas adjustments if I need to go closer to the trane max targets of 1.7" for low fire and 3.5" for high fire.

I will post the findings for comment :)

Key1

I have not heard from my BPI analyst yet but I did get to generate some additional data as promised from my quoted post above. First I decided not to pursue the 10x6 plenum register since my basement is ~1070 square feet and my water heater is only 40,000 btu. It is my understanding that my free air area is sufficient for that CAZ. I have new temp rise data, static pressure data, wattage draw data and I re-clocked the gas meters with all gas appliances off except the furnace.

All data was generated with my humidifier bypass damper closed, an outside temp of 70F, and fresh air intake dampers closed.

Gas meter clocked in low fire = 59,109 incoming BTU's
Gas meter clocked in high fire = 87,108 incoming BTU's
Both values were obtained by using the PSE&G local utilty comany gas "heating Value" of 1037.

Temp rise in low fire = 55.9F
Timp rise in high fire = 59.7F

ESP in low fire = 0.49
ESP in high fire = 0.96

wattage draw in low fire = 255 watts and 2.6 amps
wattage draw in high fire = 625 watts and 7.2 amps

Recall that my XV95 trane furnace design specifications are 65,000 btu input and 61750 output for 1st stage and 100,000 input and 95,000 output for 2nd stage.

Perhaps I may benefit from a manifold gas tweaking afterall, since it was not performed with the install.

Key1

key1cc
06-04-2009, 07:05 PM
key1cc do you intend on posting the final report?

Well, I finally got the follow up vist from my BPI anaylyst (yesterday). As impressed as I was in my first post....I am equally disapointed in this one. I was expecting a nice comprehensive report full of data. What I received was an elaborate sales pitch on why I should pay them many thousands of dollars to increase the efficiency of my home by 15%. He indicated that I do not qualify for the state rebate because they would have to increase my home's efficiency by at least 25% and since I already have new windows and a 95% AFUE furnace and 15 seer AC.....He could not get his numbers to crank out a 25% improvement even if he took my attic insulation up to R-99!

By the way, he provided no additional data. Good thing I followed him around and took notes when he came out the 1st time. I asked him where is all the data from the measurments and he indicated "consumers do not typically ask for that sort of stuff".

He basically gave me a checklist indicating everything he tested "met the BPI requirements"....but no actual values. He also played the "Green" card and indicated that if I allow him to make the improvements...... the energy savings would be equal to planting a dozen trees per year.

Sorry for the long wait.....for nothing...:(

Also I asked him why he ran the door test at 0.2 water column and he said he ran it at 50 pascals I said I know....isn't that 0.2 water column and he said no. He said 25 pascals = 2.5 water column :eek:...
I simply replied..."you're the expert...

PS I think I will go out in the backyard and plant a tree

Key1

beenthere
06-04-2009, 10:02 PM
Sometimes. The aniticipation is better then the news.

pstu
06-04-2009, 10:10 PM
FWIW I too got an "energy audit" which was a big bunch of nothing, and a "duct blaster" test which produced numbers impossible to believe. Not NJ sponsored, I'm in TX and it was from Standard Renewable Energy, right now it just looks like an excuse to pitch more products I might buy.

Am planning on a repeat of the duct blaster test which I hope might achieve believable numbers. Paying for the 2nd one too, although if it disproves the 1st then I might protest paying for both.

My sympathies -- Pstu

energy star
06-04-2009, 11:04 PM
I was waiting to see the report.......sorry about the outcome. I wanted to PM you a book link you would like but you do not have that feature turned on. I think with all the knowledge you have acquired over the past 8 months you would be able to benefit from the book.

key1cc
06-05-2009, 08:27 AM
I wanted to PM you a book link you would like but you do not have that feature turned on. I think with all the knowledge you have acquired over the past 8 months you would be able to benefit from the book.

Not sure what the PM feature is that you are referencing...How would I turn it on?
Key1

energy star
06-05-2009, 09:05 AM
Key, go to your control panel. If you click on my name "energy star" you see a drop down list appear. One of the options is to send me a private message. Now go click on yours, it's not an available option. Go to your control panel and you will find an option to activate this feature.

Shophound
06-05-2009, 09:48 AM
Key, go to your control panel. If you click on my name "energy star" you see a drop down list appear. One of the options is to send me a private message. Now go click on yours, it's not an available option. Go to your control panel and you will find an option to activate this feature.

The PM feature is not available to regular members.

Shophound
06-05-2009, 10:11 AM
Well, I finally got the follow up vist from my BPI anaylyst (yesterday). As impressed as I was in my first post....I am equally disapointed in this one. I was expecting a nice comprehensive report full of data. What I received was an elaborate sales pitch on why I should pay them many thousands of dollars to increase the efficiency of my home by 15%. He indicated that I do not qualify for the state rebate because they would have to increase my home's efficiency by at least 25% and since I already have new windows and a 95% AFUE furnace and 15 seer AC.....He could not get his numbers to crank out a 25% improvement even if he took my attic insulation up to R-99!

By the way, he provided no additional data. Good thing I followed him around and took notes when he came out the 1st time. I asked him where is all the data from the measurments and he indicated "consumers do not typically ask for that sort of stuff".

He basically gave me a checklist indicating everything he tested "met the BPI requirements"....but no actual values. He also played the "Green" card and indicated that if I allow him to make the improvements...... the energy savings would be equal to planting a dozen trees per year.

Sorry for the long wait.....for nothing...:(

Also I asked him why he ran the door test at 0.2 water column and he said he ran it at 50 pascals I said I know....isn't that 0.2 water column and he said no. He said 25 pascals = 2.5 water column :eek:...
I simply replied..."you're the expert...

PS I think I will go out in the backyard and plant a tree

Key1

In this light, may I ask you a question? Had the rater/auditor delivered the data as you anticipated, what were your intentions with the data once it was in hand? I ask because I personally think many homeowners are smarter than the average bear and have some idea what to do with the data once they have it. It is to this customer base that what you and pstu (and likely many others) received amounts to a disservice, IMO.

On the flipside, to become an energy rater/auditor/analyst requires a substantial investment of time, training, and money, so the concurrent push to sell "green" stuff or guarantee energy reduction percentages by purchasing said "green" stuff is to be expected. Nevertheless, somewhere in the spectrum should be the rater/auditor who has no vested interest in selling anything other than a thorough analysis of the building envelope and mechanical systems. An energy and comfort consultant, if you will. I have hired a structural engineer to evaluate the foundation of more than one house I have owned. He was not connected with any foundation repair companies. In my present house, he noted some deficiencies but said I needed to take no action at this time other than assure the foundation perimeter receives sufficient watering. Would a foundation repair company "analyst" have rendered such a verdict? Perhaps, but pardon my skepticism if I don't quite believe he would.

Your analyst saying "consumers do not typically ask for that sort of stuff" makes me want to ask in turn; "Do you ever offer it to your consumers?" (and if one wished to be nit-picky, I would view the recipient of an audit as a customer vs. consumer, as the recipient isn't really "consuming" anything, especially if he's given no real information).

I don't know what book energy star is hoping to direct you toward, but I have found the book "Residential Energy" to contain much useful info in an easy to read format. I purchased mine through Amazon.

beenthere
06-05-2009, 12:32 PM
Not sure what the PM feature is that you are referencing...How would I turn it on?
Key1
PM's are only available to pro members.

key1cc
06-05-2009, 01:33 PM
......may I ask you a question? Had the rater/auditor delivered the data as you anticipated, what were your intentions with the data once it was in hand? ...........

My objective is to learn as much about my system as I can, primarily driven by the lack of "correct" knowledge that I continue to encounter with the local contractors that I have had discusions with. HVAC is a very expensive purchase (for me) and I would rather not have to do it more frequently than neccessary...and I would like it to work as marketed. I also beleive (although others may not) that for my set-up, HVAC lies at the heart or air quality.... and good quality fresh air is of equal importance.

Fortunately for me, I found this site where there are quite a few very knowledgable people that are willing to help people like me.
To specifically answer your question of "what I would do with the data"....I would post it on this site for feedback from the very knowledgable pro's who have already proven themselves to me many times with the help and insight they have provided me in the past.

I understand no one is correct 100% of the time. One of the advantages of a site like this is that I get to post the info and read all of the opinions of those that care to comment........... then I am better educated to do my own research and make informed decisions.

Key1