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Community and Q&A

HRV used to vent bathrooms?

Mike Sellar | Posted in General Questions on

Hi there,

I recently purchased a spec home installed with an HRV. I’m finding that the bathrooms vent moisture horribly. Should I constantly have my Van EE system running on max so that when I turn on the “boost” switch in the bathrooms it will vent better? I noticed that this turns on the entire system throughout the entire house which makes me wonder if it’s the most efficient way to vent a bathroom. The home builder suggested only having it on when the house is full with people, this way it isn’t constantly running. This is what I’m confused about, should they have installed seperate exhaust only fans in the washrooms? I think I would’ve preferred this. I’m pretty sure I’ve tried having the Van EE system on max and the “boost” on and still I find heavy moisture build up in the bathrooms/house. I have regular inspections every 3 months for the first year and am thinking of bringing this up next time. Thanks in advance for any advice.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Mike,
    This is the second time you have posted your question. The first time was here:
    https://www.greenbuildingadvisor.com/community/forum/general-questions/13968/bathroomlaundry-vents-through-hrv

    My answer is the same:
    It's hard to diagnose the problem without knowing the cfm of your bath exhaust. Was the system commissioned? Ideally, a technician needs to measure the airflow of your bath exhaust in normal mode and "boost" mode.

    Several factors could affect the airflow, including a problem with a damper, a problem with the ductwork, or a problem with the way the system was balanced.

    After I posted the answer, you responded, "I'm not sure if the system was commissioned or what the cfm of the washrooms is. I'll have to bring this up with the home builder at our next inspection and ask then."

    I think that's a good approach. It's hard to speculate without more information.

  2. Riversong | | #2

    And I'll repost the response I offered on the other thread:

    .
    Mike,
    An HRV is designed to run 24/7 on low speed to maintain the code-minimum indoor air exchange necessary both for occupant health and for controlling humidity and mold. The bathroom boost switch is designed to give additional exhaust flow when showering, though it's rarely as effective as a stand-along bath exhaust fan.

  3. The dadaist | | #3

    two major points being missed.... or more even.

    First, we all bathe differently for different amounts of time in different enclosures in different size bathrooms with different water pressures with different deliivery..

    Second, a single point of air removal from a room is very inefficient.

    So to answer someone's question with out all the above being taken into account is not possible but the answer is still simple.

    If you have more moisture in your bathroom than you have had in a past experience then one or more of the above variables has changed including where you now live or the outside weather too.

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