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vented HPWH as sealed crawlspace exhaust?

carsonb | Posted in General Questions on

hello GBA,
HPWH is going in a small deepened section of crawl space, would be a good or bad idea to vent the exhaust only?  Crawl space walls  are insulated with R18.  If I were to vent the output of the HPWH to the exterior, it seems like this would have the benefit of removing the colder air produced (increasing efficiency of HPWH?) as well as serving as an exhaust for the closed crawl space.  I looked up a 60 gal model that was about 465 CFM, so this is far more than I would need but also intermittent.

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  1. walta100 | | #1

    Before you dig a hole in your crawlspace let talk about your lot. Could a pile at the bottom of this hole drain with pitch to daylight somewhere on the property?
    If not It seems likely that your pit could be below the water table from time to time.

    If you do not install the daylight drain what happens when the water heater leaks and fills the pit?

    A have to ask what is your crawlspace sealed away from? The exterior, the interior, or zombies?

    In my opinion crawlspaces can be vented to the exterior or conditioned. If not vented they are part of the interior space and conditioned.


    1. carsonb | | #2

      yes I should have said conditioned-- sealed to the exterior and, hopefully, zombies. This is more in reference to the methods of dealing with crawlspace air: . I have never seen anyone mention using the hpwh to deal with crawlspace air, as it can operate as either a dehumidifier (don't vent the hpwh) and potentially as an exhaust (vent the hpwh exhaust). I'm just wondering which would be better. Humidity isn't a large concern in my area, zone 5b.

      Good point about drainage. I know the entrance to the utility room in the crawlspace has a drain, but I believe it's about a foot above the utility room floor. If there were a leak, that would at least keep the whole crawlspace from flooding.

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