Comments on: 7 Tips & Tricks for Blower Door and Duct Leakage Testing

By: Leigha Dickens

Leigha Dickens — Wed, 16 Sep 2015 17:46:28 +0000

Have one of those folding
Have one of those folding ladders, not just an 8' stepladder, for houses with high ceilings, if you're short. (The vent caps don't help you with return grills.) Or have a tall assistant.

By: Sam

Sam — Tue, 15 Sep 2015 16:07:28 +0000

I would be interested in tips
I would be interested in tips for zoned systems. In my testing, zoned systems have increased in a major way over the last couple of years. If I have a problem, it will be with a zoned system.

By: Ned Fischer

Ned Fischer — Tue, 15 Sep 2015 01:45:38 +0000

In my experience, if total
In my experience, if total duct leakage fails, do outside duct leakage. It is a good test to see where the leaks are. Especially if the air handler is in conditioned space. (means only supply ducts are in attic and leaking.)

By: Colin Genge

Colin Genge — Fri, 11 Sep 2015 09:36:24 +0000

I meant to say:
I meant to say: I strongly advise duct testing under DEpressurization. The extra time ensuring register seals are in place and the chances of a seal blowing off and wrecking your test do not make it worthwhile. I know of NO good reason to test ducts with positive pressure. Sucking air out of ducts is faster and more consistent. There are a few points to remember when applying negative pressure and that topic could justify an article. Results will be identical if you connect your equipment up according to manufacturer's directions.

By: Ted Kidd

Ted Kidd — Fri, 11 Sep 2015 00:22:30 +0000

In reply to Franklin Menendez. slick!
slick!

By: colin genge

colin genge — Thu, 10 Sep 2015 15:39:59 +0000

I strongyly advise duct
I strongyly advise duct testing to be done under pressurization. I understand that it's a bit more of a hassle to change ranges but apart from that, the only other good reason for it is that the tester has its face stuck in the flex which shouldn't be a problem. We are undertaking to compare calibrations in both directions for the DuctBlaster and the Rt DucTester to see if there is any difference.

By: Penut Rachel

Penut Rachel — Thu, 10 Sep 2015 07:04:28 +0000

If you are also getting your
If you are also getting your house infiltration cfm for your Manual J load calculation leave the duct system taped and put the shower cap over the duct blaster so that you take the ducts out of the blower door infiltration number. Manual J's infiltration number is not intended to include the leakage through the ducts. The duct leakage is accounted for separately by Manual J. Anyone else ever looked at those vent caps under infrared???? I have, a few times, it was very pretty seeing all the air leakage. I"m curious if anyone else has gotten a better seal than what I have experienced.

By: Dan Perunko

Dan Perunko — Thu, 10 Sep 2015 06:54:14 +0000

If you add a second blower
If you add a second blower door test with your duct system sealed, seal the duct tester fan as well, you get a handy while not perfect infiltration value attributable to the duct system. In your test order it would come right after duct lekage to the outside.

By: David Butler

David Butler — Wed, 09 Sep 2015 22:30:42 +0000

In reply to Mark Crawford. @Mark, I know that some
@Mark, I know that some trainers teach that duct mask should only be applied to the grille face, leaving any gaps between the grilles and drywall (or floor) open. That's incorrect. Grilles should always be taped or sealed to the substrate. Here's why: During normal air handler or furnace operation, little if any supply air leaks backwards through gaps around the boot. Those gaps are mostly an infiltration path, not so much a duct leakage path. Keep in mind that during normal ops, static pressure at the boot is very low. Mostly what you have is velocity pressure. That means that the only supply air that leaks backwards into the attic or crawl is what happens to be deflected off the back side of the grille. It's well understood that duct pressurization overstates leaks in and around the boot, and understates leaks near the blower. The duct test fan artificially creates a static pressure of 25 Pascals at the grille, which is MUCH higher than normal ops. So when you only mask the grille face, leaving the grille-drywall gap untaped, static pressure induced by the duct test fan forces air backwards through those gaps, thus creating a leakage path that does not exist under normal ops (or greatly exaggerates that path). So taping the grille to the drywall or floor best reflects normal operation. In reality, those gaps are mostly an infiltration path. The blower door will pick them up.

By: Ben Kershner

Ben Kershner — Wed, 09 Sep 2015 20:49:59 +0000

Don’t hit the chandelier when
Don’t hit the chandelier when you remove the door frame.
Don’t stand on the hose.
Don’t throw the outside hose into a puddle.