Manual J calc, who does it?

[George2]

I read a lot of posts (here) about the importance of doing a Manual J load calc.

I see the importance of it for cooling, I'm not quite as concerned on the heating side with the (newer) multi-staged furnaces.

Of course with geothermal sizing it's a must.

Okay, here's the thing, I've sold hvac for 30+ years. No one, I mean no one, does or offers doing a Manual J in my area of 300,000 people.

I think it's because of the time it takes. Also, I'm sure alot is because they don't know how or care.

Thanks

[adamwhatley]

Are you asking who does? If so then i do. How do you size your homes out? Let me guess 500 square foot per ton? I am not making a joke but that is a common practice around our area as well but not me going to pull a tape on it, get window sizes and direction, wall and ceiling insulation, duct work and return etc...

What i run into is that duct system are too small along with returns so you can put the biggest system you want to in there and it still want move anymore air or return then what the duct system will allow. the unit will be loud, uses a lot of energy, short cycles and does not truely keep the people comfortable.

[George2]

Adam,
Thanks for the reply. I've struggled with this for some time. I've run it by my wife (who's very smart) and she can't see (understand) the logic verses the time it requires.

I was taught 600 sq. ft per ton on a ranch and 700 sq. ft. per ton on a 2- story. The furnace requirements are 35-40 btus per sq. ft.

I have been down sizing on the newer homes plus I take into consideration the sun and wind (in the country) exposure.

When I suggest duct modifications (which I offen do), people will say, "The last three guys didn't say anything about that."

It can be a rewarding and frustrating profession.

[ball a/c]

Are you asking who does? If so then i do. How do you size your homes out? Let me guess 500 square foot per ton? I am not making a joke but that is a common practice around our area as well but not me going to pull a tape on it, get window sizes and direction, wall and ceiling insulation, duct work and return etc...

What i run into is that duct system are too small along with returns so you can put the biggest system you want to in there and it still want move anymore air or return then what the duct system will allow. the unit will be loud, uses a lot of energy, short cycles and does not truely keep the people comfortable.

Adam, I thought we were supposed to stand in the street and hold up our fingers. If it took 2 fingers to cover the house it took 2 tons, 5 fingers 5 ton.

[Hunter844]

Adam,
It can be a rewarding and frustrating profession.

This is pretty much verbatim how we do it.

Every new construction project gets a load calculation performed.

However most of the time we don't do a load calculation unless the home owner asks for it or in many cases we just know by looking at the house that it's been added onto and needs a proper assessment. Otherwise we normally just ask the homeowner how their comfort-level has been with the old system and go from there.

In the last few years I've been seeing more and more competitors quotes accompanied by Wright Soft load calculations. I have also seen several that I viewed as totally incorrect as if they were cookie cutter load's on the ready.

One the reasons I joined this forum was to learn what other companies are doing basically in all aspects of this industry. My company is more or less at a crossroads as it's family run and my father and uncle are nearing retirement age. I have to guard against "doing things the way they've always been done" vs. learning new ways to skin a cat. Sometimes it can be like pulling teeth to our people to make sure they are keeping up but there again when it's been working for so long it's also hard to argue with results.

I certainly want to make sure we're giving our customers the best job they can get and lately especially with these tax credit systems I've come to realize perhaps we were guilty of selling equipment people didn't need and I want to get back into the mode of really outlining what I feel like my clients need and not necessarily what they are asking for.

[ball a/c]

Hunter,
We run loads on every replacement job we do. Most customers are happy if the system cools. They aren't aware of the dangers of a humid house. With the world full of attorneys, I would make every effort to cover yourself. I have been in business for 46 years and I'm learning new things ever day. We can't be satisfied with the status quo. When I started I did things the best I knew how. I know more now.

[Ed Janowiak]

I do / did lots of them.

Manual J or load calc are much more than determining what size heating or cooling plant is required for a structure.

What about how many BTUH you need going where?

I don't understand why so many people like to guess or wing it when it can be so easy if you just put a little effort into it. Proper design is not hard, but guessing sure is easier.

(not intended to be an insult to the OP just a general observation of our industry as a whole)

[youarerelevant]

In our area, there is an ever growing trend with the counties to require a load calculation on each addition and new construction house. I reluctantly bought Hvac Calc and learned how to complete a load calculation from the helps on the program. It took a while to measure a retrofit and complete the first few loads. I always forgot to find out which way was north and what color the roof was.
Now we perform a load on each retrofit. I can measure a small house with a $12 sonic tape measure, draw it on graph paper and enter it in Hvac Calc in 30-45 minutes. I feel much more confident about the install. I often win a new customer replacement by explaining the importance of accurate sizing to the customer.
Hvac Calc is great but it does have its limits, it is not accepted by the energy star rater in my area. FYI

[eyeseeitall]

Illinois has passed adopted the 2009 International Energy Conservation Code- which requires load calcs on every job- new or replacement. Enforecement by different AHJs varies still as not everyone is a believer. I happen the believe it is a good idea, but I don't run my department and can't make my boss (The AHJ) require them.

[George2]

This is pretty much verbatim how we do it.

Every new construction project gets a load calculation performed.

However most of the time we don't do a load calculation unless the home owner asks for it or in many cases we just know by looking at the house that it's been added onto and needs a proper assessment. Otherwise we normally just ask the homeowner how their comfort-level has been with the old system and go from there.

In the last few years I've been seeing more and more competitors quotes accompanied by Wright Soft load calculations. I have also seen several that I viewed as totally incorrect as if they were cookie cutter load's on the ready.

One the reasons I joined this forum was to learn what other companies are doing basically in all aspects of this industry. My company is more or less at a crossroads as it's family run and my father and uncle are nearing retirement age. I have to guard against "doing things the way they've always been done" vs. learning new ways to skin a cat. Sometimes it can be like pulling teeth to our people to make sure they are keeping up but there again when it's been working for so long it's also hard to argue with results.

I certainly want to make sure we're giving our customers the best job they can get and lately especially with these tax credit systems I've come to realize perhaps we were guilty of selling equipment people didn't need and I want to get back into the mode of really outlining what I feel like my clients need and not necessarily what they are asking for.

Hunter,

Your situation sounds like the normal HVAC shop. Many are second or third generation shops.

I agree also with the 2009-10 tax credits assessment, contractors were installing 2 ton A/Cs because the (needed) 1 1/2 ton wouldn't meet the SEER.

The biggest problem in my area is that the ductwork is so undersized. The "car salesman turned HVAC expert" are telling the customers that the ECM blower motors will solve ALL the problems.

Welcome to the site. There is good and bad information so continue to do your homework. I still study (read) almost everyday. The new equipment is so much more sensitive and complicated as I'm sure you know.

[George2]

In our area, there is an ever growing trend with the counties to require a load calculation on each addition and new construction house. I reluctantly bought Hvac Calc and learned how to complete a load calculation from the helps on the program. It took a while to measure a retrofit and complete the first few loads. I always forgot to find out which way was north and what color the roof was.
Now we perform a load on each retrofit. I can measure a small house with a $12 sonic tape measure, draw it on graph paper and enter it in Hvac Calc in 30-45 minutes. I feel much more confident about the install. I often win a new customer replacement by explaining the importance of accurate sizing to the customer.
Hvac Calc is great but it does have its limits, it is not accepted by the energy star rater in my area. FYI

I hope no one thinks I don't believe in the value of a proper load calc. I really think it's important. But like I said earlier, no one is doing it here. It's not going to happen until it's required.

But with the time it takes to access the poor ductwork (I do mostly retrofit) and to explain all the differant benefits of furnaces, heat pumps, IAQ products, air conditioners and lets not forget they want a bid on geothermal "just to see if it's in the budget" I get paid less than the techs.

[BaldLoonie]

Any rule of thumb or so many BTUs per sq ft is meaningless.

It's amazing how many jobs we do where we are putting in smaller equipment, in some cases much smaller. And we are quoting smaller than the competition who guess or base it on the old oversized unit.

It doesn't take long to do a simple whole house calc. If you do it, you can educate the customer into why the furnace should be sized right. It will set you apart from the competition, you'll be quoting smaller, less expensive equipment.

Oversizing 2 stage units isn't helping your customer, they are getting screwed out of the benefit of having a properly sized 2 stage unit. They are really ending up with an expensive single stage unit.

Today's high efficiency A/Cs can be worse at latent removal than an oldie and they take longer to get to full latent capacity. So if oversized, that's a double whammy. ball points out why that is bad.

[skippedover]

I once worked for a company that wouldn't know a Man 'J' if it were printed in stone and dropped on their toes. But ever since I started my own business, I've done a Manual 'J' on ever single job. And that's for both heating and cooling.

You think it's less important for heating than for cooling? Well if a cooling system is grossly oversized, the HO is uncomfortable but as long as the coil doesn't freeze, that's the end of the story. But if furnace is grossly oversized, it rides on high limit and will likely suffer a premature HE failure.

What I do know is that 2/3 or more of the systems on which I do a Man 'J' have oversized equipment. Anectdotaly, my service manager came into my office recently with a house plan and asked me to do a load analysis on it for his uncle. His uncle lives out of our area so there's no competition there. The person proposing a new AC system quoted on a 4.0-ton system, stating the 5.0-tons would be better but they could 'get by' with a 4.0-ton system. He also had a 150,000 Btu mod/con boiler installed.

The house area is 1740 square feet and the heating load is 34,000 Btu's, while the cooling load is 1.5-tons!!! So much for rule of thumb, eh?

Looking at it a little differently, think about this. A room is 10 x 10. How much cooling does it need? No remove all windows and doors leaving 4 outside walls. How much cooling? Now replace all the walls with 8-foot sliding glass doors and in the ceiling put 4 2x4 skylights. How much cooling does it need? Mind you, all 3 examples have the same square foot dimension. Using the same examples, how much heat does each need?

So square footage, vast years in the business, just look and know! These are all ways of looking a customer right in the eye and as much as stating, "Hey, look at me. I've got so many years of experience that I can cut corners and you'll never know the difference." Until I come along. Then they'll know the difference. Read my attachment and see if it sways you at all.

[George2]

Any rule of thumb or so many BTUs per sq ft is meaningless.

It's amazing how many jobs we do where we are putting in smaller equipment, in some cases much smaller. And we are quoting smaller than the competition who guess or base it on the old oversized unit.

It doesn't take long to do a simple whole house calc. If you do it, you can educate the customer into why the furnace should be sized right. It will set you apart from the competition, you'll be quoting smaller, less expensive equipment.

Oversizing 2 stage units isn't helping your customer, they are getting screwed out of the benefit of having a properly sized 2 stage unit. They are really ending up with an expensive single stage unit.

Today's high efficiency A/Cs can be worse at latent removal than an oldie and they take longer to get to full latent capacity. So if oversized, that's a double whammy. ball points out why that is bad.

B.L.

I've always had a high regard as to what you say on this forum. I absolutely agree with everything you said on both counts.

I know I'm sizing smaller than my competitors even without a load calc. because I am paying a lot more attention to insulation upgrades, new windows and sun exposure.

I do not size by what is in the house now. I look at it from a professional stand point but I've been trying to convince my wife of the benefits (as if she was a consumer) and I can't make any head way.

I see were it will help sell but I'm trying to justify the added time. Again, as mentioned earlier, it's hard enough explaining the lousy ductwork (modifications) when the other 4 salesman "didn't think it was necessary."

Thanks for listening. I'm going to have a drink now and chill. LOL.

[George2]

I once worked for a company that wouldn't know a Man 'J' if it were printed in stone and dropped on their toes. But ever since I started my own business, I've done a Manual 'J' on ever single job. And that's for both heating and cooling.

You think it's less important for heating than for cooling? Well if a cooling system is grossly oversized, the HO is uncomfortable but as long as the coil doesn't freeze, that's the end of the story. But if furnace is grossly oversized, it rides on high limit and will likely suffer a premature HE failure.

What I do know is that 2/3 or more of the systems on which I do a Man 'J' have oversized equipment. Anectdotaly, my service manager came into my office recently with a house plan and asked me to do a load analysis on it for his uncle. His uncle lives out of our area so there's no competition there. The person proposing a new AC system quoted on a 4.0-ton system, stating the 5.0-tons would be better but they could 'get by' with a 4.0-ton system. He also had a 150,000 Btu mod/con boiler installed.

The house area is 1740 square feet and the heating load is 34,000 Btu's, while the cooling load is 1.5-tons!!! So much for rule of thumb, eh?

Looking at it a little differently, think about this. A room is 10 x 10. How much cooling does it need? No remove all windows and doors leaving 4 outside walls. How much cooling? Now replace all the walls with 8-foot sliding glass doors and in the ceiling put 4 2x4 skylights. How much cooling does it need? Mind you, all 3 examples have the same square foot dimension. Using the same examples, how much heat does each need?

So square footage, vast years in the business, just look and know! These are all ways of looking a customer right in the eye and as much as stating, "Hey, look at me. I've got so many years of experience that I can cut corners and you'll never know the difference." Until I come along. Then they'll know the difference. Read my attachment and see if it sways you at all.

Thank you for your information. I am going to start doing load calc with a laptop and Wrightsoft. I hope it sets me apart. It really would not take much. Most of the salesmen around here can be in and out of a home in 10- 15 minutes. One lady asked why I had a tape measure! Another lady, when I started to measure her ductwork got angry. She had a bad 5-7yr, old Lennox condenser. I found (after she cooled down) that 3 returns had been omited because of a wall removal. No one else even looked.

[Hunter844]

Honestly...until I can control 100% of the sales process in my company...I can't make the claim to doing a load calculation on every job. I will however make an effort to do them on every job I personally do a site survey on.

One thing I really want to do before the summer hits is get a new manual-j program. I'm pretty much self-taught on a program called RezCalc which is old school stuff (made by Carrier Corp). I've been knowing for a while that RezCalc is a dinosaur and I'm sure other more modern programs are way more accurate.

I will acknowledge that here in the past few years we keep getting these large RNC jobs, houses 5000+ sq foot that have high ceilings and are well insulated...the loads using RezCalc come out with some pretty wonky figures that I don't necessarily trust always.

I may check into WrightSoft next time I see a class in my area. I do want to be formally taught load calculations. Are there any other manual-j products I should consider?

Do those of you that do a lot of manual-j's...do you go conservative on your outside peak? In other words...In Arkansas we'll have summers where the temp is in the upper 90's and 100's for several days. I've been to some meetings in the past where the guy speaking would say to go with an average temp instead of a peak. For someone that's never been formally taught this stuff...can someone explain that thought process?

[jimj]

Do those of you that do a lot of manual-j's...do you go conservative on your outside peak? In other words...In Arkansas we'll have summers where the temp is in the upper 90's and 100's for several days. I've been to some meetings in the past where the guy speaking would say to go with an average temp instead of a peak. For someone that's never been formally taught this stuff...can someone explain that thought process?

This is how ALL manual j's should be done. What you stated above is why manual j's by different people are all over the place.

[Hunter844]

This is how ALL manual j's should be done. What you stated above is why manual j's by different people are all over the place.

I'm not one of the cool kids yet...can't access it. :whistle:

[jimj]

I'm not one of the cool kids yet...can't access it. :whistle:

Well, if you had your email in your profile I could help with that.:bsing:

[Hunter844]

Well, if you had your email in your profile I could help with that.:bsing:

My bad,

It's in there now.

[jimj]

My bad,

It's in there now.

You have mail, hope it will open for you.

[George2]

This is how ALL manual j's should be done. What you stated above is why manual j's by different people are all over the place.

JimmyJ,

I hope I have enough color ink in my printer. LOL. What did we do before computers, fax machines and cell phones?

Thank you for the information.

George

[jimj]

Your Welcome.:yes:

[tedkidd]

Full audit including blower door test. Every job. Cost benefit on improvements and equipment sized to match existing or improved conditions.

Pretty nice here in NY with the Green Jobs Green NY program paying us $250-$400 for every audit. Everyone gets 10% rebate on the contracted work. NY will subsidize unsecured loan rate down to 3.5% if the improvements model payback shorter than life expectancy.

Have to be a caveman not to do it.

[George2]

Full audit including blower door test. Every job. Cost benefit on improvements and equipment sized to match existing or improved conditions.

Pretty nice here in NY with the Green Jobs Green NY program paying us $250-$400 for every audit. Everyone gets 10% rebate on the contracted work. NY will subsidize unsecured loan rate down to 3.5% if the improvements model payback shorter than life expectancy.

Have to be a caveman not to do it.

Some utilities to the south of us are giving rebates to the customer for a load calc.

Rebates are not offered yet with our local utility company. I would like to charge around $250 to perform a load calc. I think some customers would see the value.
But again, I'll be up against 3 or 4 others that will say it's not needed.

[udarrell]

Full audit including blower door test. Every job. Cost benefit on improvements and equipment sized to match existing or improved conditions.

Pretty nice here in NY with the Green Jobs Green NY program paying us $250-$400 for every audit. Everyone gets 10% rebate on the contracted work. NY will subsidize unsecured loan rate down to 3.5% if the improvements model payback shorter than life expectancy.

Have to be a caveman not to do it.

Way to go Tedkidd.
That is really the only way to go.
There is a huge shortage of home AUDITORS!

Start with the home Energy Audit, then the manual J, then equipment sizing, Manual D duct system design & doing all the other INSTALL step by step Best Practices Procedures, including blower CFM checks.

Also, during the cooling season doing the easy & relatively fast Ball-Park testing of real-time BTUH Output of the system.

HO, knows they got what they paid for.

These practices are far more important than the difference in SEER!

You & HO keep the permanent records for future testing comparison referrals. Hey, George2, Good Thread. :pop:

[George2]

Way to go Tedkidd.
That is really the only way to go.
There is a huge shortage of home AUDITORS!

Start with the home Energy Audit, then the manual J, then equipment sizing, Manual D duct system design & doing all the other INSTALL step by step Best Practices Procedures, including blower CFM checks.

Also, during the cooling season doing the easy & relatively fast Ball-Park testing of real-time BTUH Output of the system.

HO, knows they got what they paid for.

These practices are far more important than the difference in SEER!

You & HO keep the permanent records for future testing comparison referrals. Hey, George2, Good Thread. :pop:


Thank you, Darrell. It's always good to hear from you.

I wonder (maybe I should start a new thread) if there would be a business opportunity offering the above test for all the HVAC companies in my area that won't take the time, don't care, don't know and never offer it to the homeowners.

George (B)

[bigtime]

Well, Im probably in the minority, but after you do this for a while its not hard to figure out what size unit a house needs. If a house has lots of windows or no windows you need to be careful. Otherwise, they are all similar. One ton for every 700-800 sq ft. Oversize a lttle for a heat pump. Seal the duct.

[jimj]

Well, I'm probably in the minority, but after you do this for a while its not hard to figure out what size unit a house needs. If a house has lots of windows or no windows you need to be careful. Otherwise, they are all similar. One ton for every 700-800 sq ft. Oversize a Little for a heat pump. Seal the duct.

Thats what I thought for my first THIRTY YEARS, now I know after the last ten years of doing manual j's I was WRONG!

I will ask my son how many sq ft a particular house is that we are doing a load on and he will say who cares? And you know what he's right. In my part of the country 35% to 45% of the load on the average home is window load, what does that have to do with sq ft?

[George2]

Well, Im probably in the minority, but after you do this for a while its not hard to figure out what size unit a house needs. If a house has lots of windows or no windows you need to be careful. Otherwise, they are all similar. One ton for every 700-800 sq ft. Oversize a lttle for a heat pump. Seal the duct.

You're getting closer..........I'll tell you a short story to prove the importance of correctly sizing the A/C.

When I bought my home it was about 1600 sq. ft., 2-story, built 60+ years ago. Can anyone say, "Where's the insulation?"

It had a 2.5 ton A/C. I put on a 300 sq. ft. addition and it was still working fine. When I put in a new hi-eff. furnace and A/C I stayed with a 2.5 unit.

But the new A/C would not de-humidify. Not until I added another room addition bringing my total sq. ft. to 2250 did we feel comfortable again.

Do the math, 900 sq. ft. per ton in a poorly insulated home. What would it be in a home with insulation in the walls, with low-e windows with north-south (not east-west like my house) sun exposure!

[bigtime]

I have a 2000 sq ft home with a 2 1/2 ton ac unit. I think I did a load calc when I installed it, but I cant remember. It replaced a 3 ton unit. Design temperatures are 93 deg, and it cuts on/off when its 100 deg outside. House stays dry and cool.

Dehumidifying is more about getting the air cold than longer run times. If you put a 2 1/2 ton unit on a furnace with a 3ton blower, you may need to put the blower on medium speed for cooling.

[adamwhatley]

I can see the o/p is wanting to the right thing, which is doing a load on every house he looks at. The problem he is stating is the time it takes to do the load & talk to the customer. He is right it does take time but needs to done. This time of year is a great to get started doing loads as most hvac companys slow down.

When summer hits & we are doing 2-5 homes a day loads take time & we all want to see every customer. There are times when I do just want to go in & look at customers existing system & give estimate off there current size but I don't, I have to do A load so I can sleep at night knowing I did right by the customer.

Even when you have done 100's of loads on homes & you think you figured out the right square footage per ton you go to the next & everything is different then what. My point is there is no square foot per ton size that applys to every home. I have downsized so many systems that I have lost count & have also had to increase the size will this is a low number. If you can find a simple load sheet to do in the field & once back at the office check your load it will be a lot less time you have to use.

My wife was the same way saying to me why do you spend so much time doing what you do? I always tell her that it is because it is the right thing to do. When you do the doctor you want him to spend time with you going over everything not just a come in & say I think I know what is wrong & this meds might fix it. You are on the track of doing what needs to done to help your customers.

[roadrunnerderek]

I have read this thread through. I do see the importance of doing load calculations. Doing the "math" does look like the best way to size heating/cooling equipment and exactly where the conditioned air is going to matters a lot. I do watch out for lots of windows, insulation quality, thickness of walls, skylights, etc. I read the ACCA notes talking about watching the overhangs for shading (good points), etc. Years ago I bought a bunch of manual J books. I tried using them initially but they are collecting dust mostly. Don't tear me up too much... at least I bought the books. Are there any recommendations for getting more training in how to use these programs. Do I have to go to some special schooling somewhere? Will it cost thousands (an arm and a leg)? Trying to manually following the J calc book would take a lot of time it seems. I admit I need training on how to do things fast and right. Or is this something that just takes either a great set of blueprints or a thorough inspection of an existing home filling our a big checksheet you later input into a load calc program?

[tedkidd]

Thats what I thought for my first THIRTY YEARS, now I know after the last ten years of doing manual j's I was WRONG!

I will ask my son how many sq ft a particular house is that we are doing a load on and he will say who cares? And you know what he's right. In my part of the country 35% to 45% of the load on the average home is window load, what does that have to do with sq ft?

Nicely put. And common variation in air leakage can throw another 30-40% variable in load. If $1000 worth of air sealing could improve comfort, reduce replacement equipment size, and reduce the energy bill by $X, wouldn't you want to know and solve for X before making a 15 year equipment investment?




Dehumidifying is more about getting the air cold than longer run times. If you put a 2 1/2 ton unit on a furnace with a 3ton blower, you may need to put the blower on medium speed for cooling.

Huh? Where is beenthere or teddybear when you need them?

[Gunslinger]

I have read this thread through. I do see the importance of doing load calculations. Doing the "math" does look like the best way to size heating/cooling equipment and exactly where the conditioned air is going to matters a lot. I do watch out for lots of windows, insulation quality, thickness of walls, skylights, etc. I read the ACCA notes talking about watching the overhangs for shading (good points), etc. Years ago I bought a bunch of manual J books. I tried using them initially but they are collecting dust mostly. Don't tear me up too much... at least I bought the books. Are there any recommendations for getting more training in how to use these programs. Do I have to go to some special schooling somewhere? Will it cost thousands (an arm and a leg)? Trying to manually following the J calc book would take a lot of time it seems. I admit I need training on how to do things fast and right. Or is this something that just takes either a great set of blueprints or a thorough inspection of an existing home filling our a big checksheet you later input into a load calc program?

Although I'm not an ACCA member, I have gone thru their $800.00 class on design. They do a good job teaching this stuff if you get the right instructor. They use Wrightsoft.

A little story.... I went on a service call for poor heating. Home had 2 systems in it. One was a 2 ton and one was a 3 ton that had been changed out a few years ago. My call was on the 3 ton. Upon turning the system on, it sounded like a tornado. This was for the kitchen living, dining, and TV room. I honestly don't know how they could even watch TV. I checked the tesp and it was .8 or better. Duct work completely too small for a 3TON.

I did a manual J and D to see if I could run the house on 3 ton. It was a no go. I needed 4 ton. I suggested replacing the 3 ton with a 2 ton. They told me the original system was a 2 ton. Amazing, imagine that. The new system is quiet, humidity is way down, and her power bill is much lower. I'm sure others have run into similiar situations. This shows the importance of proper sizing. This lady is a relative of a friend and I'm constantly hearing how much she loves her new system and how great I am.

In another post, someone mentioned using an E
to correct for improperly sized ductwork. Yes, sometimes it can be done but the energy usage will be higher.

Learn the Manual J and D and be ahead of the competition.

[paul42]

I have a 2000 sq ft home with a 2 1/2 ton ac unit. I think I did a load calc when I installed it, but I cant remember. It replaced a 3 ton unit. Design temperatures are 93 deg, and it cuts on/off when its 100 deg outside. House stays dry and cool.

Dehumidifying is more about getting the air cold than longer run times. If you put a 2 1/2 ton unit on a furnace with a 3ton blower, you may need to put the blower on medium speed for cooling.

I'm glad I did my own manual J - 2 tons for 4,000 sq. ft. Works great.

[bigtime]

Huh?

There is nothing more important in dehumidifying a space than getting air as cold as possible. Cold air cant hold as much mositure as cool air. It is a very common mistake to have to much airflow which gets cool but not cold.

[bigtime]

I'm glad I did my own manual J - 2 tons for 4,000 sq. ft. Works great.

You definately have an unusually well insulated/tight house. My 700-800 ton per sq ft rule of thumb is for normal houses around here.

[Roadhouse]

I'm glad I did my own manual J - 2 tons for 4,000 sq. ft. Works great.

Your home is apparently a legend. It was brought up to battle my ignorance concerning sizing many, many months ago.

[udarrell]

You definately have an unusually well insulated/tight house. My 700-800 ton per sq ft rule of thumb :oops: is for normal houses around here.
We know you meant 700-800-sf per ton of cooling...

My 1937 farm home works perfect with 1600-sf per ton of cooling. :bsing:

[bigtime]

We know you meant 700-800-sf per ton of cooling...

My 1937 farm home works perfect with 1600-sf per ton of cooling. :bsing:

Opps. Thanks Darrell. :grin2:

[George2]

I'm glad I did my own manual J - 2 tons for 4,000 sq. ft. Works great.

Paul,

Where do you live, the North Pole? LOL

Anyway, with 4,000 sq. ft. and all the ductwork, you're moving 800 cfm.

There can't be much air movement. Basically you are just de-humidifing.

[tedkidd]

That's like 4 window units, 1 for every 1000 sf.

Doesn't seem unreasonable, particularly if zoned. Do you setback?

What size furnace?

[jdaley]

I wonder (maybe I should start a new thread) if there would be a business opportunity offering the above test for all the HVAC companies in my area that won't take the time, don't care, don't know and never offer it to the homeowners.


After doing several thousand energy audits and consistantly seeing oversized units I started offering a heat loss/gain calculation to HVAC contractors in conjunction with the energy audit the customer is already getting. Unfortunately the uptake has been pretty low. Some contractors say "I've been doing this for xx years and I already know what I'm doing", some say "customers don't want a quiet system, they want a hot blast of air they can hear and feel". Interestingly this company's customers are consistently complaining that their new equipment isnt as quiet or comfortable as the sales person said it would be....

[tedkidd]

Poorly sold systems to people used to freezing their butts off, standing over a blow torch grate to warm their feet, using aggressive setback to "save energy" and complaining when properly sized equipment blows "colder air" and doesn't heat the home "up" fast enough are all significant educational/ignorance challenges. People still think having equipment NOT run saves energy. They don't see their homes as losing heat continuously throughout the season whether equipment is running or not.

Time to educate, particularly when people want easy, quick solutions, and the extra time doesn't equate to increased commissions and can potentially queer the sale are all burdens that work against the approach you offer.

Unfortunately energy is relatively cheap, until that changes significantly, reasons to correct imbalanced homes will be slow to gain traction.

[paul42]

Paul,

Where do you live, the North Pole? LOL

Anyway, with 4,000 sq. ft. and all the ductwork, you're moving 800 cfm.

There can't be much air movement. Basically you are just de-humidifing.

North Central Texas.

No, there is not a lot of air movement, but I don't need a lot.
It makes for a VERY quiet system. I put a streamer on the duct in my office so I can tell when it is on.

and no, I do not use setback. The house gains and loses heat so slowly that it is not effective.



Shade all the windows in the summer.
Put the air handler & duct work in conditioned space.
Air seal the house.

[tedkidd]

and no, I do not use setback. The house gains and loses heat so slowly that it is not effective.



Ho boy. Now you've done it. You may get some Nitwits that start saying you lack common sense and are an unpatriotic waster of energy.

[commerce48]

Setbacks are less "effective" in tight homes, meaning that they save less money. It doesn't mean that setbacks don't save money, they do.

If he has a tight house, he is not losing much energy. That is a very different situation from most American homes. In addition, he is not recommending his personal choice for others, nor has he denied the basic laws of thermodynamics. Only you do that. You cite one source to back you up, and that source said that setbacks "work well" for gas forced air furnaces.

Again with the name calling. Why? It is unprofessional and against the rules. If you want to make an argument for your point of view go ahead. You need a good argument for a claim that setbacks don't save energy.

[tedkidd]

That source says oversized gas furnaces. You propose patriotic Americans should live in leaky, poorly insulated homes with oversized furnaces so they can save money by using your beloved setback strategy? We should all go back the 70's, driving cars that get 12 mpg and "save" by driving 55? Living in incredibly wasteful homes suffering discomfort may be the American way, but unless you are from the middle east I wouldn't call that patriotic.

Oh, and you don't think attempting to measure savings is a good idea, simply have faith that it saves because you say so. Be a patriotic American, shut up and drink the cool aid. Homes are simple things, they all perform the same.

You sound like the guy, usually the drunk at the party, who "can get better mileage by not using cruise control". But never tracks his fuel use. I ask him how much he saves, he says "lots". Its disappointing, and sounds pretty stupid to me.

[RoseRx]

Why is the Manual J so critical, when the choice in heat pumps is only 2, 3, 4 and 5 tons and I would think most competent HVAC guys could size up a home's needs in a matter of minutes vs calculating a list of variables?

[beshvac]

Why is the Manual J so critical, when the choice in heat pumps is only 2, 3, 4 and 5 tons and I would think most competent HVAC guys could size up a home's needs in a matter of minutes vs calculating a list of variables?

1. Actually the sizes are 1.5 2.0 2.5 3.0 3.5 4.0 5.0

2. The environment they work in is also a factor. that 2.0 ton AC in one climate might put out 23,500 Btu/h at the hottest day of the year. In a hotter climate that same 2.0 Ton AC might only put out 21,000 Btu/h and the next size bigger is needed.

[commerce48]

That source says oversized gas furnaces. You propose patriotic Americans should live in leaky, poorly insulated homes with oversized furnaces so they can save money by using your beloved setback strategy?

All gas furnaces are oversized most of the time. That is what your article said. Most patriotic Americans live in poorly insulated homes with gas furnaces. Why shouldn't they be able to save money with setbacks? Who are you to tell them they won't? They will.

Why don't you tell beenthere to stop turning his furnace down when he leaves home, because he can't save money? Or not enough to meet your threshold because you have money to burn.

No need to measure unless you want to know the magnitude of savings. Everyone knows when you turn off a light, you are no longer using energy. Not much savings, but it adds up. Everyone knows when you stop the draft under the door, you save energy. Not much, but it adds up. Everyone knows when you turn down the thermostat, you save energy. What the heck do you think a setback is? It is turning down the thermostat, something that cannot fail to save energy.

Except for those who have a wild belief that the laws of physics don't apply because of "complex nuances". It is unfortunate that such people are allowed to misinform homeowners.

[RoseRx]

I have not seen many heat pumps w/ SEERs > 15 in 1/2 ton denominations.

[Hunter844]

I have not seen many heat pumps w/ SEERs > 15 in 1/2 ton denominations.


TRANE 4TWR5042E (others in that series are half-ton rated)

I do agree there probably aren't many. As the SEER/HSPF ratings go up you'll start to see more half-ton rated units manufactured I would think.

[RoseRx]

So, if we do not have a 1/2 ton incremental heat pump ratings, then why the need to have such specific Manual J calculations?

[jimj]

So, if we do not have a 1/2 ton incremental heat pump ratings, then why the need to have such specific Manual J calculations?


The majority of the systems your talking about are multistage capacity.
So if your needing a 3 1/2 ton system a Trane 20i would be a great choice, it has a 2 ton and a 4 ton compressor giving you the best of both worlds.

[udarrell]

Originally Posted by commerce48
All gas furnaces are oversized most of the time. That is what your article said. Most patriotic Americans live in poorly insulated homes with gas furnaces. Why shouldn't they be able to save money with setbacks? Who are you to tell them they won't? They will.

Everyone knows when you stop the draft under the door, you save energy. Not much, but it adds up. Everyone knows when you turn down the thermostat, you save energy. What the heck do you think a setback is? It is turning down the thermostat, something that cannot fail to save energy.

Except for those who have a wild belief that the laws of physics don't apply because of "complex nuances". It is unfortunate that such people are allowed to misinform homeowners.

If you dress a lot warmer, as I do, U can lower the thermostat.
I set mine at 60F except when taking a shower, & I'm comfortable.
This way I don't need to use a humidifier.

I also wash my clothes in cold water &, during cold weather hang dry them in the house, - automatic humidification.

Temp difference between indoors & outdoors determines rate of heat exchange, less temp difference less runtime, it makes a lot of difference in the number of cycles per hour.

Each cycle Oil & Gas Furnaces run for quite some time before the blower kicks on. My stat is away from any SA heat source so it runs longer on each cycle saving energy.

Yes, it's oversized, & probably not even a 75%'er now at around 25 seasons.
Yes, I need a new smaller furnace but Thermo Prides' aren't cheap.

I will be getting a home energy audit & doing what's necessary to downsize the furnace a lot.
I have two small half-ton window A/Cs.

I don't have a set-back stat, so sometimes I set it back when I'm gone for some time.

Yes, setbacks are okay, but getting an energy audit & then reducing heat-loss & gain is what we should all do.

There is a terrible shortage of Home Energy Auditors; that needs to change!

[tedkidd]

There is a terrible shortage of Home Energy Auditors; that needs to change!

It's a demand problem. Hopefully demand will grow for building science, then it won't be such a foreign language.

Sort of like your comment about humidity. Unless you understand psychrometric charts that comment might be pretty confusing.

[udarrell]

It's a demand problem. Hopefully demand will grow for building science, then it won't be such a foreign language.

Sort of like your comment about humidity. Unless you understand psychrometric charts that comment might be pretty confusing.
I discovered there are govt home efficiency audits in WI, however those that qualify for them may have to wait 6 months for an audit.

I would like to know what the situation is in everyone's state regarding Govt or Energy Company help, from all those following this thread.

Home & small business energy audits could be a huge generator of business for H-VAC contractors.

The more skills your company develops or works with auditors & weatherization companies the more opportunities you potentially could gain.

There is no safer investment or positive ROI for those with money or access to money to invest in reducing their utility bills.

The DEMAND won't be there unless we can get the MEDIA to focus on these Private Sector economic creation factors, & focus elected representatives, along with our advertising & communications in that direction. These actions will also help save their jobs!

Those with money to invest or lend at low interest rates, have the potential to jump-start this critical energy economic sector.

They could buy needed instruments (blower door, duct blasters & infrared, & put them in Rentals at low rates for H-VAC contractors to use, etc.) toward incorporating this essential process in their business.

Everyone needing to replace equipment ought have an energy audit performed first, so they can downsize replacement units.

If the money is made available to them so the savings, over-time, pays off the loan, that process has potential to work for everyone in our industry.

Too much typing for me; but I want to help you, if possible, improve your bottom-line! - Darrell

[jimj]

I would like to know what the situation is in everyone's state regarding Govt or Energy Company help, from all those following this thread.

Our utility has required manual j's to be done to receive there rebate, however most have just turned in bogus loads. No more, they are requiring the homeowner to have an energy audit, will require the installing contractor to be BPI certified and will be conducting test outs. For the first time they will be looking at the house as a system.:cheers:

[udarrell]

Our utility has required manual j's to be done to receive there rebate, however most have just turned in bogus loads. No more, they are requiring the homeowner to have an energy audit, will require the installing contractor to be BPI certified and will be conducting test outs. For the first time they will be looking at the house as a system.:cheers:
I don't like the idea that only BPI can train & certify energy efficiency auditors!

BPI charges a lot for the training & certification that could be performed by other sources, including Tech colleges.

I never like to see one source dominating all the training & certification of an industry without any competition!

Before replacing equipment, everyone ought to be told to do weatherization on their home or business & have duct systems & airflow checked.

It appears nearly everyone on this thread disagrees with me.(?)

I believe all of us need to speak-up & act or we & our industry will simply lose business we should have acquired. The customer's will also lose the savings benefits they deserve to receive for their relatively large investments.

A Higher SEER A/C or efficient furnace won't achieve their expected savings "without those other factors being properly addressed, first."

If I ever go back into business replacing equipment, the sequence will start with a home or business energy audit, followed by all the other Best Practices in the proper order.

I am NOT train-skilled to do audits, so until then, I'd have to find someone to work with me, along with someone doing weatherizing.

However, those business skill-jobs can be incorporated into one's Energy Efficiency Business Ventures. Always say, - Yes We Can...

IMHO, it's the proper way to do it right for the customer.

The best situation is when the Utility Energy Company provides a Quality energy efficiency audit from which contractors can work. :cheers:

[jdaley]

In Canada, we are at the tail end of the Eco-Energy program. The program works as follows:

Pre-retrofit energy audit. Auditor makes recommendations and provides a report that shows how much energy would be saved by specific improvements (both building envelope and mechanical improvements).

Homeowner has up to 18 months to make improvements to their home.

Post retrofit audit. House is re-tested, upgrades are verified by auditor. Auditor submits paperwork to Natural Resources Canada, who issues a cheque to the homeowner.

There are grants available for everything from furnaces to insulation, to Energy Star windows. There is also a seperate grant available for reducing the air leakage of the house (as measured by the blower door tests).

The documentation requirements are extremely high, so there is little opportunity for fraud (ie. date stamped picture showing furnace connected to ductwork and venting system, date stamped picture of model and serial number, etc.)

The program runs from March 2007 to March 2011 and has been used by approximately 300 000 homes in Canada. There are rumors that it might be extended past 2011 but not likely since cutting budgets is now the political flavour of the week.

[tedkidd]

BPI charges a lot for the training & certification that could be performed by other sources, including Tech colleges.

Actually, BPI provides curriculum, performance and health & safety standards, and the classes are taught at community colleges and BOCES.

I never like to see one source dominating all the training & certification of an industry without any competition!

Before replacing equipment, everyone ought to be told to do weatherization on their home or business & have duct systems & airflow checked.

I like the idea of at least KNOWING the opportunity, and incentives for higher saving opportunities, not sure compulsory improvement requirements is a great idea.


I believe all of us need to speak-up & act or we & our industry will simply lose business we should have acquired. The customer's will also lose the savings benefits they deserve to receive for their relatively large investments.

A Higher SEER A/C or efficient furnace won't achieve their expected savings "without those other factors being properly addressed, first."

If I ever go back into business replacing equipment, the sequence will start with a home or business energy audit, followed by all the other Best Practices in the proper order.

I am NOT train-skilled to do audits, so until then, I'd have to find someone to work with me, along with someone doing weatherizing.

However, those business skill-jobs can be incorporated into one's Energy Efficiency Business Ventures. Always say, - Yes We Can...

IMHO, it's the proper way to do it right for the customer.

The best situation is when the Utility Energy Company provides a Quality energy efficiency audit from which contractors can work. :cheers:

I usually either learn from you or agree with you. In the case of the utility performing audits, NY tried that and it was ineffective. Only so much can be taught in classes. Understanding the cost of improvements is a really important component of accurate cost/benefit analysis, someone removed from performing the work simply doesn't know cost so their reports tend to be very inaccurate.

[udarrell]

I usually either learn from you or agree with you.

In the case of the utility performing audits, NY tried that and it was ineffective. Only so much can be taught in classes.

Understanding the cost of improvements is a really important component of accurate cost/benefit analysis, someone removed from performing the work simply doesn't know cost so their reports tend to be very inaccurate.
Well, here is where I learn from your actual experience, & I can clearly see where that would generally be true.
(Added) We contractors know more about optimizing H-VAC performance efficiencies as related to the whole home concept.

I was trying to take the auditing burden off the H-VAC contractor, however, utility companies would probably never have enough well trained & highly skilled auditors to effectively cover their customers.

A major problem is the lack of auditors & the "wait before an initial audit gets performed."

Auditor jdaley's post concerning how they do it in Canada was very interesting. It can get drawn out over considerable time up there, as the homeowner has up to 18 months to make the recommended improvements.

It is interesting to note the large variations between our states & other countries regarding their incentives & procedures.

[tedkidd]

NY process sequence just got stretched a week to a month.

Now you apply for a free audit and receive a "reservation" number. (If you get the application right this adds 7 days. Get it wrong this adds a month)

Schedule the audit. - 1-3 week depending on matching schedules.

Pay the auditor using your "reservation" number.

Receive Comprehensive Home Analysis (computerized report of audit results and

improvement cost/benefit analysis - hopefully with high AND low performing recommendations - this proves audit firm isn't cherry picking recommendations they want to sell but are modelling all potential opportunities to determine worthiness)

Mull it over and tweek packages to fit budget and needs. Some homeowners pull the trigger right away but most do not. This part many contractors, used to a short sale cycle, really despise.

Contract

NY review of computer model, Approval of contract and work-scope.

Schedule

Complete

Test out/qc

So this can take some time, but for the few client's I've tracked the results meet or exceed modeled savings (I needed to be confident in the software so I tracked).

It has also allowed me to sell nothing but top of the line equipment and improvements in an area that most seem to sell crap.

I am a gear geek, have come to understand the energy and comfort benefits of "best". Also, I hate hearing tales of woe from people who regret buying crap, when for a small increment their problems could have been solved.

[tipsrfine]

I was a participant in a program that failed. The program did require than an energy audit be performed, and all of the independent auditors did run into serious time delays due to having to get the cost numbers from the contractors performing the work. I don't think that makes the case for saying energy audits shouldn't be performed by independents. Only an independent auditor has the freedom to give completely honest recommendations to a homeowner.
I think these programs could work around the problem of independents not knowing the exact cost of their recommendations. You don't need to know the exact cost before being able to safely inform the customer that their conditioned area of the home has a large amount of air connections to the attic/outside and that they will improve their comfort & save money on their utitility bills by having them air sealed. Let the onus of making this work cost effective & all of that number crunching fall to the contractors.
An energy audit should be a resouce a customer can use & trust, not a sales tool used to sell products & services by a contractor.

[SkyHeating]

I know this thread has gotten a little off topic but to the OP Yes I perform a Manual J on all AC, Heat Pump and Geothermal systems but rarely for a furnace unless I am nervous the blower on the furnace will be undersized if they or the next homeowner were to add AC/HP down the road. There are very few that do a Manual J and about 2 that do it right. In Portland we are heating dominate but most people fudge their Manual J numbers to show that the homeowner needs a 80K BTU or 100K BTU furnace or just don't do it right in the first place. They show a 92K BTU heat loss in a 3200 sq foot house, base on our energy rates that shows a customer with a $500 a month bill in the winter when they are having $250 bills. The ones that I see do them seem to have the AC side somewhat figured out but still don't go in depth enough with leaky/sealed ductwork and what insulation values/types of windows, they just put a standard insulation, standard window and go off sq footage, no better than usuing a rule of thumb.

[kls-ccc]

As a contractor I would like to think we are all ethical enough to do energy audits & provide the services and equipment to fix the problems. However I am not niave enough to believe this would be true for all contractors. That is where the problem lies. If a customer gets cheated by just one contractor it brings the whole industry down. You can't regulate morals so there is no way to stop those looking to make a buck by cheating people.

As for the load calc, I do one on almost every install we do. It does take time and it bugs me when a contractor comes in and doesn't do a proper load calc checking insulation values etc. And it does make a difference. I did a bid on a 2700 sq ft home with full basement, the load came out 3 ton. My competitor came bid 2 - 3ton units, I bid 1 - 3ton unit. We were higher but got the job. The customer has not had a problem with heating or cooling in over 10 yrs. so ya, they work.