Home energy audit, blower door test

[NextEndeavor]

A utility hired energy efficiency contractor/consultant will be here tomorrow. They will open an outside door, install a sealed computer controlled fan to put a slight vacuum on the house for the purpose of finding leaks. I told the guy yesterday about the wood stove. He wasn't concerned about the negative pressure back drafting the chimney but has also never came across wood heat. I'm going with a light load tonight and nothing in the morning. Hate to run the $NG but don't want to risk smoke in here. Chimney has never back drafted, not even in warmer weather. Thoughts?

 

[weatherguy]

I have an insert so I had to let it go cold to do the test, if your stove's not running you should be ok.

 

[begreen]

Sounds like a reasonable concern. I'm surprised that the auditor has not run into this before.

 

[DougA]

The neg. pressure they create is very slight. I've had it done. I would have some duct tape handy to seal the air vents in the stove just so that it doesn't screw up the readings. I would not worry about dust or smoke blowing into the house but you would want to have the stove coll/cold because a roaring fire will give you wrong results. I don't doubt that they have not run into this before. Not that many 'real' woodburners out there. Most do it on cold nights when they want romance.
If they aren't already doing it, you want to have a smoke stick so you can go around and find any major air leaks. They will show-up fast.

 

[woodgeek]

Your stove draft will NOT beat the 50 Pa depressurization. The auditor manual says that all combustion devices must be OFF during the test. Close your vents, and hope you don't dump too much CO this morning from coals into your house.

 

[semipro]

Aside from the obvious back draft risk the flow of air out the chimney skews the blower door test results. The stove should be turned off and the flue blocked during the blower door test.

 

[EatenByLimestone]

Your stove draft will NOT beat the 50 Pa depressurization. The auditor manual says that all combustion devices must be OFF during the test. Close your vents, and hope you don't dump too much CO this morning from coals into your house.

Just shovel the coals into your metal ash bucket.

 

[woodgeek]

How'd it go? CFM50? ACH50?

 

[jdp1152]

I was told to not have a fire for 48hrs prior to the blower door test for my audit.

 

[NextEndeavor]

The blower door test was educational. They open an outside entry door fully and block it off with a variable speed fan that essentially sucks on the house and blows it outside. The equipment has two probes to sample the outside barometric air pressure and the inside air pressure. A small computer controls the fan to create a slight negative pressure. It wasn't even enough pressure difference to be felt in our ears. Then we walked all over the house checking for air leaks coming in from the outside. It was cold out so easy to detect. Most 120v electrical outlets on outside walls had some leakage. My oldest windows did pretty good for 1968 installation. The surprise was our newest bathroom exhaust fan. Apparently the flapper in the attic is stuck open. Our drier vent worked perfect. It is the new style with an enclosed cap that slides up/down and it did a good job of being completely sealed. As for the wood stove, I had ran pine and soft maple through it so by 8 am even the coals were nearly gone, all of which hit the garden before the guy arrived. With inlet air closed all the way, we could just barely detect any reverse draft air. Then I made a foolish mistake ...... and opened the air control ... stupid. We were curious how that effected the total air intake/leakage number. Well, I think we swept the chimney and any ash that would have been above the burn tube baffle! Yep, you guessed it, a face full of airborne ashes. Good thing the lady wasn't home. Bottom line, the house was a lot tighter than I expected. He said I'm boarder line needing one of those air exchange deals. The stove always works fine so I won't change anything except cleaning the bathroom exhaust fan flapper. Forgot to mention the closet ceiling area where the attic entry is didn't leak either.

 

[DougA]

Great that you reported back. I guess I should have clarified my post about no dust or ash coming into the house. Yup, if you open it up while the house is de-pressurized (even though it is so slight), you'll have a problem.
It shows you how easily a back draft can occur if you had the kitchen & bathroom fans on while running the stove.

 

[johnny1720]

When the guy came to do my blower door test he made a terrible error. He never shut my oil furnace off. When he turned the negative pressure on the furnace kicked on. The fire did not stay in the firebox and it did not turn off. It kept pouring the fuel oil into what it thought was the burn chamber. It roasted all the controls on my furnace. It also cooked the burner motor all wiring and everything else the fire touched. It almost burned my house down and it spilled diesel fuel all over my basement.

Cost me big money to get the heat back running.

 

[begreen]

That's awful. You shouldn't be paying for his negligence. The guy's liability insurance should foot the bill.

 

[johnny1720]

The reason the guy was doing it was he was doing the home energy audit for my geothermal. So the guy who installed the geo gave me a credit for the furnace repair. Of course it had to happen in January and of course I had a brand new baby and no heat.

I think the energy auditor was dumb to put it nicely.