Testing for air pressure in a house.

Discussion in 'HVAC Heating & Cooling' started by Mikebarone, May 17, 2008.

  1. Mikebarone

    Mikebarone DIY Senior Member

    Messages:
    206
    Location:
    Phoenix, AZ
    I have learned on the plumbing forum how to make a low cost water column tester. This tester is used to test for leaks in gas lines with a very low pressure, (about ½ PSI). I was wondering if there is a low cost device that would measure in Pascals? I was going to use my home made water column tester, but after learning that 50 pascals equal about 0.20 inches of a water column, I don’t think that the water column tester will be sensitive enough for what I’m going to use it for.

    Thanks much,

    Mike

    PS. I'm going to be doing a blower door type of a test on my buddy's house to look for A/C duct leaks in his attic. I'll be pressuring his house and using a smoke bomb to try and find any leaks.
  2. Bill Arden

    Bill Arden Computer Programmer

    Messages:
    584
    Location:
    MN, USA
    It's hard to making a sensor that is both easy to make, calibrate, and not subject to being damaged by large pressure swings.

    I would recommend trying a small garbage bag.
    1. take a small garbage bag. (bathroom type)
    2. Tape the end over a piece of cardboard so that the channels in the cardboard can be used as the input pipe.
    3. tape hose, ect to fill the bag.
    4. Lay sheets of paper on the bag until it's roughly flat and barely puffs up.
    5. Weigh the paper sheets and divide by the square inches.

    The real question is why you need to measure the pressure?
    If all you are doing is finding leaks, just having pressure is enough.
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    If a guage is normally used on a blower door test , then I am sure it is commercially available and not too expensive. But just knowing that you have pressure seems like enough to do a smoke test.
    Here are some links to testing, and they mention the 50 pascal #, so I assume you have already done this research. I notice the testing is done with a vacuum in the house, not postive pressure

    http://www.eere.energy.gov/consumer/your_home/energy_audits/index.cfm/mytopic=11190
    http://www.infiltec.com/inf-btst.htm

    Here is a link to a guage:
    http://www.energyconservatory.com/download/dg700brochure.pdf and another http://www.retrotec.com/products/gauges/dm2_series_2_channel_digital_p/


    I couldn't find any site actually selling those guages. I guess they would run a few hundred.
    Last edited: May 19, 2008
  4. Mikebarone

    Mikebarone DIY Senior Member

    Messages:
    206
    Location:
    Phoenix, AZ
    Thanks all for your inputs!

    Thanks all for your inputs!
    I did find a web site, (and there is probably a lot out there) that have a hand held meter with a fan blade mounted on top of the meter, and as it spins it will give you CFM and the ambient tempeture. I could get a fairly nice one for around $200.00, but after making that monomer for around $20.00, I got cheep, and I though I would get some info off of this forum before I went out and got one.
    I though I would pressurize his house to use the smoke bombs work, because if I created a vacuum in the house, I don’t think the smoke bomb would work. I agree with everyone that a meter would not be needed for the smoke bomb test, but it would be nice to know how air tight the rest of the house is too…ie outlets, can light, fire place dampers etc.
    Thanks for the web sites; I’ll give them a look see.

    Thanks again,

    Mike

    PS. I’ll have to re-read the plastic bag test that was suggested, and digest it a little better….Thnaks!
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    If you put a pressure on the house, then release smoke inside, you may see generalized movement in a direction. If you have a vacuum on the house, and probe around windows, doors, electrical outlets, etc. you probably get a much more specific location of the path of the air leak.
  6. Mikebarone

    Mikebarone DIY Senior Member

    Messages:
    206
    Location:
    Phoenix, AZ
    Thanks Jimbo!

    The smoke bomb I was going to set off inside of his air-handler that’s located in a closet in a hallway, (after tapping off all of his delivery vents) so the smoke wouldn’t be in the entire house.
    You do have a great point about detecting leaks around all outlets etc. I’ve read that incense sticks can be used around the smaller areas, (wall plugs, can light etc). I guess there is a reason the pro’s create a vacuum in the house huh. Blowing air into the house it’s also going to be hard to limit the turbulents in the house. I think I’m going to blow for the smoke test, for the duct leak test in his attic and suck for the outlet tests….no pun intended….LOL.

    Thanks Jimbo!

    Mike
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