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Having my duct work checked for leaks, efficiency.

Greg808 | Posted in General Questions on

Before getting an HRV installed I figure I should make sure my duct work is in order and I’m wondering who is best to look into that for me.

I had some HVAC guys in and asked about some weak airflow to some vents. They said they can check with a tool how well the air is getting up and adjust the dampers but that was it.

I was wondering specifically about checking if there are any leaks in the ducts. Or if the ducts are not structured or arranged in the best way.

I thought the HVAC guys would be the most logical for that. But they said they don’t look inside the ducts for leaks. Is that normal?

Maybe I just got the wrong HVAC company?

Or do I have to go to a duct cleaning company for that? I thought they wouldn’t have the technical knowledge of the general ventilation, how it was installed ect.. beyond the cleaning.

Or do I go to a contractor to look at the setup?

Or go to 3 different companies for balancing, cleaning, and build inspection?

Who should I go to here?

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Replies

  1. Expert Member
    DCcontrarian | | #1

    Do the ducts run entirely through conditioned space? If that's the case, leakage doesn't affect efficiency unless it's so extreme as to create localized overheating and overcooling. Just balance for comfort.

  2. walta100 | | #2

    My feeling is that anyone offering duct cleaning should be considered suspicious at best and scam artist at worst.

    Before you jump on the HRV bandwagon.
    Has your home been blower door tested under 2 ACH50?
    Is it more than 40°F cooler outside than insides for months at a time?
    What is the occupation decently?

    If the home is a very leaky 1950s cape cod in southern Texas that is empty 14 hours a day with 2000 square feet per occupant an HRV would be silly.

    If your old leaky duct work in in the vented attic or vented crawlspace getting them air sealed is a good idea. Money spent sealing the ductwork in your basement would be wasted.

    Walta

  3. nynick | | #3

    In my town they required a duct leakage test as part of the CO process. I failed the first two times (over 600 CFM total loss!) until I called another testing outfit who spent the time to find the leak. It was where the return duct met the ceiling drywall. That seam had not been caulked and was leaking a huge amount of air into my CONDITIONED attic.

    Yes, they require duct leakage testing even for ducting within conditioned spaces. The numbers to pass the test are different for conditioned versus unconditioned, but there are still values that need to be met. Passing grade was below 8CFM per 100sf in my case.

    Of course I was "losing" heated air into my conditioned attic, but I'd rather have that air fed into my living space before it wafts up into my attic.

    Google "Duct Leakage testing" for your area. I think the last test cost $400.

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