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Community and Q&A

DIY blower door test?

Nick Welch | Posted in Green Building Techniques on

This page describes how to build a DIY blower door:

http://www.builditsolar.com/Projects/Conservation/BlowerDoor/BlowerDoor.htm

Basically you use a furnace blower and a cheap magnetic or tube-of-water manometer. You can’t finely tune the speed of the blower like a professional blower door, but given the few built-in speeds of the motor, you can generally find a speed that yields close enough to 50Pa that you can extrapolate the CFM50.

I have a furnace fan already sitting around from my decommissioned oil furnace, and I just bought a Dwyer Magnahelic manometer on Ebay for $15. Is this crazy or should it really work as described?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Nick,
    As long as you plan to use for the first two purposes described in the article -- to "find air infiltration leaks into your house" and to "trace your progress in sealing the house" -- this approach should work just fine.

    I don't think that this set up would be accurate enough to extrapolate a cfm50 number at 50 pascals. But accuracy isn't particularly important for the two purposes under discussion.

  2. Nick Welch | | #2

    Thanks Martin. Finding leaks is easy with any big enough fan. I was really interested in being able to track my progress and see the air leakage number go down as I seal things up. I realize it won't be accurate enough for me to go around boasting about my CFM50 number, but as long as I can see relative improvements in some quantitative way without scheduling and paying for a professional blower door test, that is pretty awesome.

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