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Blower door. Who has one? Who uses one?
It seems to be a great compliment to HVAC. If you own one, how often do you use it?
We got a blower door and a duct blaster from a guy who used to be a home energy auditor. I was excited to get them as they were in excellent condition and we negotiated a trade for an installation.
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https://www.hvac20.com/ High efficiency equipment alone does not provide home comfort and efficiency. HVAC2.0 is a process for finding the real needs of the house and the occupants. Offer the customer a menu of work to address their problems and give them a probability of success.
Find contractors with specialized training in combustion analysis, residential system performance, air flow, and duct optimization https://www.myhomecomfort.org/
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I have been blower door and duct blaster certified for 3 years. I have the equipment to do both. I have done a lot of blower doors, but only one duct blaster. NY only requires duct blaster if ductwork goes outside the conditioned space.
You will be shocked at the places a building leaks when you do blower door.
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We have had a blower door and duct blaster for many years. Prior to me taking ownership and for the first several years after that, I had no idea how beneficial / eye opening it was to run a blower door. Now we're able to dial in our load calcs to be very accurate. We don't use the duct blaster much because most systems are not in unconditioned space where I'm from. Following the HVAC-2.0 process has been a game changer for us! (Located in the Cincinnati / Dayton, Ohio area).
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How does a blower door test help you do load calc? Other then fluff added for infiltration?
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Originally Posted by
heatingman
How does a blower door test help you do load calc? Other then fluff added for infiltration?
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Load calcs make assumptions based on what we tell it about the house. Infiltration is a guess which can be way off. Some estimates have shown that the load calc can be off by as much as 30-50% with the wrong infiltration rate.
I found at my own house that the gap between the rough frame and the finished frame of the windows and doors hadn't been filled or sealed which contributed to noticeable infiltration. I had to remove trim for all of them to remedy that. I've been finding leaks at my own house that I wouldn't have expected.
I have seen builders in a hurry and they did not insulate the framing on exterior corners. Installation of fiberglass batts is usually poor because the insulation is compressed to fit around pipe, wires, and boxes so voids are left. I can't tell by looking a house if the builder put forth the effort to seal the house or not.
The blower door gives me a much better number to enter in a load calc for an accurate result.
Last edited by kdean1; 12-11-2020 at 12:29 PM.
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https://www.hvac20.com/ High efficiency equipment alone does not provide home comfort and efficiency. HVAC2.0 is a process for finding the real needs of the house and the occupants. Offer the customer a menu of work to address their problems and give them a probability of success.
Find contractors with specialized training in combustion analysis, residential system performance, air flow, and duct optimization https://www.myhomecomfort.org/
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Have thought about getting it as I generally analyze customers homes in order to do a thorough manual J. I also recently got a thermal camera to help advice customers on infiltration/exfiltration issues. I try to look at the building envelope rather than just thinking about the equipment. Of course if you do a thorough man J it makes you think about stuff like this, fenestration types etc.
I've not got one yet mainly due to the cost and some uncertainty on ROI.
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In washington were required to perform a duct leakage test when we install a new furnace. We have to attach a report to the furnace and the inspector checks for that. Over the last 9 years I've caught probably 6 notable cases where the client had a major defect in their ductwork.
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Blower door tests are done at such high pressures that without interpretation if you size the HVAC by the results it will be oversized. Duct leak tests for resi are a complete waste of money. Duct leak tests at pressures below 3 inches are totally stupid. The most efficient method of controlling leakage in resi ducts is a reasonable specification that is enforced.
Before you guys get too upset check SMACNA recommendations.
No man can be both ignorant and free.
Thomas Jefferson
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Originally Posted by
WAYNE3298
Blower door tests are done at such high pressures that without interpretation if you size the HVAC by the results it will be oversized. Duct leak tests for resi are a complete waste of money. Duct leak tests at pressures below 3 inches are totally stupid. The most efficient method of controlling leakage in resi ducts is a reasonable specification that is enforced.
Before you guys get too upset check SMACNA recommendations.
I kinda had the same thought about them. They don’t create a real world scenario. I wonder how many places show up as leaks on one of those that wouldn’t actually be a leak under normal conditions.
I would almost think a really good thermal scan would be more realistic as it would be done under more normal conditions.
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Originally Posted by
WAYNE3298
Blower door tests are done at such high pressures that without interpretation if you size the HVAC by the results it will be oversized. Duct leak tests for resi are a complete waste of money. Duct leak tests at pressures below 3 inches are totally stupid. The most efficient method of controlling leakage in resi ducts is a reasonable specification that is enforced.
Before you guys get too upset check SMACNA recommendations.
I’m just curious what customers in residential are paying for a blower door test? It’s like pulling teeth just to upsize the duct work to the bare minimum standard.
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I had to deal with blower door tests doing TAB and they were nothing but a pain in the rear. The tests were run at a negative 0.3 inches. They certainly caused leaks that not only would not have normally leaked but a lot of them would have self sealed over time. When they first became popular most of the testers didn't know what they were doing and I had to be there or the test got screwed up. It was common for them to kill power to an outside air damper with it open and not check to make sure it was closed and not all of them were normally closed. I think the commercial tests should have been run twice once at -0.3 and once at positive 0.05 to 0.08. That would have helped find leaks but would have also given a realistic test of the normal leakage level.
Most duct leak tests failed on the first try when tested at 0.3 inches and above until the contractors realized they had to implement a good procedure for sealing and then the sailed through.
Just two cents from the TAB point of view.
No man can be both ignorant and free.
Thomas Jefferson
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I don't know the cost of blower door testing CircusEnvy.
No man can be both ignorant and free.
Thomas Jefferson
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Originally Posted by
WAYNE3298
Blower door tests are done at such high pressures that without interpretation if you size the HVAC by the results it will be oversized. Duct leak tests for resi are a complete waste of money. Duct leak tests at pressures below 3 inches are totally stupid. The most efficient method of controlling leakage in resi ducts is a reasonable specification that is enforced.
Before you guys get too upset check SMACNA recommendations.
Can you clarify about the duct leakage test being a waste of money for resi. I was assuming you can run the test at a realistic pressure - maybe 0.7" WC or so - and then look at leakage.
Do you have a link to the SMACNA recommendations you mention?
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Sorry szw21 I don't have a link to SMACNA duct leakage. I sold my duct leak equipment when I retired and the manual went with it. SMACNA actually tells you that in some cases duct leak testing is a needless expense. If I recall that remark was meant for 2" design pressure and below. If you need to run a duct leak test or specify max leakage use the duct external area method not percent of leakage. Honestly a leak test at 0.7" is a real waste. Not trying to put you down because I realize you are trying to be thorough and I admire that.
I don't know if you can get an on line copy of the manual but you can order it from SMACNA or get it through your local union.
No man can be both ignorant and free.
Thomas Jefferson
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Originally Posted by
James Colver
In washington were required to perform a duct leakage test when we install a new furnace. We have to attach a report to the furnace and the inspector checks for that. Over the last 9 years I've caught probably 6 notable cases where the client had a major defect in their ductwork.
What were the major leaks? I can imagine a return chase not closed or ducts off at the trunk.
If ducts are outside the envelope, that kind of leak can be identified with a blower door.
*********
https://www.hvac20.com/ High efficiency equipment alone does not provide home comfort and efficiency. HVAC2.0 is a process for finding the real needs of the house and the occupants. Offer the customer a menu of work to address their problems and give them a probability of success.
Find contractors with specialized training in combustion analysis, residential system performance, air flow, and duct optimization https://www.myhomecomfort.org/
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I did some digging and found a copy of the SMACNA HVAC AIR DUCT LEAKAGE TEST MANUAL. SMACNA does not recommend leak testing ducts constructed to 3" w.g. and below. This is from the first edition 1985. This is a good manual with a lot of information on leak testing and sealing. If I was going to do leak testing I would get an up to date copy but there probably aren't many changes.
No man can be both ignorant and free.
Thomas Jefferson
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Originally Posted by
WAYNE3298
I did some digging and found a copy of the SMACNA HVAC AIR DUCT LEAKAGE TEST MANUAL. SMACNA does not recommend leak testing ducts constructed to 3" w.g. and below. This is from the first edition 1985. This is a good manual with a lot of information on leak testing and sealing. If I was going to do leak testing I would get an up to date copy but there probably aren't many changes.
Thanks - I will look into getting the manual - need to convince myself that is it worth spending the $ for it. I have a login on the SMACNA website but I'm not a member so I don't think I have access to much
So what's the logic behind not testing ducts designed for < 3" wg. You mentioned you had some duct leak equipment you sold - what does that equipment do. I assume it is not a duct blaster type setup?
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To do duct leak tests you need at least 2 blowers of different size. For each blower you need a tube with a flow orifice to measure the airflow. United McGill is big on these which is what I had and what I would recommend. The manual is small and not likely very expensive.
The logic behind not testing ducts designed for 3" and below is all ducts should be sealed and if properly sealed they will have little leakage. Disruption to the job more than offsets the benefit of testing.
i LOOKED IT UP AND THE NEW MANUAL COSTS $104. There is an article though that will answer a lot of your questions for free.
No man can be both ignorant and free.
Thomas Jefferson
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Originally Posted by
WAYNE3298
To do duct leak tests you need at least 2 blowers of different size. For each blower you need a tube with a flow orifice to measure the airflow. United McGill is big on these which is what I had and what I would recommend. The manual is small and not likely very expensive.
The logic behind not testing ducts designed for 3" and below is all ducts should be sealed and if properly sealed they will have little leakage. Disruption to the job more than offsets the benefit of testing.
i LOOKED IT UP AND THE NEW MANUAL COSTS $104. There is an article though that will answer a lot of your questions for free.
So how would that be different to using the duct blaster and setting it to 2 different speeds and measure the airflow for each instead of two separate blowers?
Yes I agree ducts should be well sealed. However in a lot of older homes they are not. I had a thread a while ago in the resi forum. I have a customer who had a comfort complaint. I went and performed a bunch of tests. The main issue was that the upstairs unit was low on refrigerant tracked to a leak in the evap. But in addition using my new flowhood I determined that the return air was only about 1/2 of what it should be based in TESP readings for the downstairs unit. I made up a test fixture using a box fan and a fog machine and we found when the fog was injected we saw the fog leaking out of an outside extractor fan vent.
Customer says he will find the issue and fix but I don't think he has done that yet. A leakage test should have found that although the smoke helped track it down.
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As long as you can get the needed airflow it doesn't matter what fan you use. You also have to measure the flow. The purpose of the two blowers is so you can select the size blower you need for the job. They are not used simultaneously. You have to calculate the allowable leakage for the application and then choose the fan you need.
For big leakage as far as I'm concerned a smoke test is a good way to find it. The purpose of a duct leak test is to determine if the ducts are sealed good enough to limit leakage as specified.
Duct leakage tests are not run using TESP it is the pressure in the portion of the duct you are testing.
No man can be both ignorant and free.
Thomas Jefferson