How to lower humidity
gmsturchio
| Posted in General Questions on
Moved into new 630 sq ft home, 1 bed/1bath. Ducted mini-split. ERV. Indoor humidity ~84%! ERV set at 20 cfm; reduced from 40 cfm with no change. Indoor temp 70, outdoor today mid-60, rain clearing. Indoor humidity 80%+ for last week regardless of rain or no rain. Could it be problem with ERV? Thanks.
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Replies
Sounds about right. Indoor 70F with 84% rel humidity= indoor dew point 65. Rain outside = 100% rel humidity with temp 65F = outdoor dew point 65.
Remember an ERV is not a dehumidifier, it will transfer some moisture in or out along with ventilation air but doesn't actively remove moisture. If you're not running your indoor AC or an indoor dehumidifier, there's no dehumidification going on, so your indoor air will be at the same dew point as outdoor air.
You'll need to buy a dedicated indoor dehumidifier (which will warm the space up) or run your mini split on dry mode if it has it (which will cool the space down).
Try turning the split unit on AC with the fan on the lowest setting, temp set low enough for it to run
I have a dehumidifier in my crawl space and another in my main living space. While mine are fancy Santa Fe models that I don't have to manually empty, I started out with a basic model from a hardware store and was so happy with how much better it made the air feel. An ERV won't decrease humidity unless it is less humid outside.
With an outdoor temp of 70 degrees, open the windows when it's nice out.
I had a similar problem with my new garage apartment. Since it's new construction, everything needs to dry out. Buy a dehumidifier, open the windows as much as you can and run the ac.
My Mitsubishi thermostat also reads RH incorrectly and high. A cheap Walmart thermometer was better and matches the readings on the dehumidifier.
Thank you to everyone for their responses.
Note running the ERV when the outdoor dew point is higher than the indoor dew point will increase the indoor humidity and lower your comfort level while making the AC use more energy.
Generally, it is a good idea to run a dehumidifier in a new construction home thru the end of the second heating season.
630 is not a lot of square feet. How many people and animals occupy the building for how many hours a day?
Walta
What you described is pretty much the way it should be. Depending on the local climate, 84% humidity in residential unit is not surprising at all. If you don't like it, either run your AC harder or put a dehumidifier, which essentially also cooling. Personally speaking, small dehumidifiers you can get in costco or walmart are either too crappy or too expensive, run AC harder is what i do at home.