ERV to remove moisture from building
raskoosk657
| Posted in General Questions on
House built in the 2000s, brick and cmu. Moisture issues has plagued this house from the beginning. Most of the original batts between joists have been removed and rigid board installed on top of the roof deck. Brick has been sealed recently. But the smell of mold persists.
the idea with the ERV is to place one end in the soffit to suck up all the moisture. Do you think this will work. Attached is a drawing
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That's not really how ERVs work. As the intake and exhaust air are passing each other inside the unit, they exchange both heat and moisture, so they reduce how much moisture is gained or lost inside the building compared to HRVs, which don't exchange moisture.
In other words, if you have an air conditioner or dehumidifier that has dried the indoor air compared to the outdoor air, an ERV will keep the indoor air drier than an HRV would, but it will still introduce some humidity from outdoor.
When it's more humid inside than outside, typically when it's cold outside, an ERV will take less humidity from indoors than an HRV would, but it still has a net effect of reducing the indoor humidity.
If high humidity is the problem--it should be no more than 50% RH at ±70°F indoors--then a dehumidifier would be a better choice.
One thing I don't like about your proposed assembly is that you are trying to draw mold-ridden air across fiberglass insulation in your ceiling assembly, and reintroducing it to your furnace where it can be spread around the house.
Your drawing is a little scary in that it seems you may not be fully conditioning the old attic.
It looks like you may have left the od insulation in place. You need the attic to be more or less the same temp and humidity as the rest of your home. Leaving the old insulation in place is an impediment to that goal. The risk is if you ignore the attic it may end up being very humid and when it gets cold surfaces could fall below the dew point and stuff will get wet and moldy.
HRV and ERVs are only helpful for removing moisture when the outdoor dew point is lower than the indoor dew point.
Where do you think the moisture is coming from and can you do something to control it at the source.
If you live swampy south east you may need to resign yourself to the fact that a dehumidifier and AC need to run most of the year.
Walta