ERV and humidifier (its too dry now)
tighterhouseNH
| Posted in Mechanicals on
Recently installed an ERV and going through first winter.
(Glad I didn’t choose an HRV to make sure we lost enough humidity!).
The ERV is working well, the condensation I used to get on my windows in winter is gone. However, the RH inside gets down to the 25% range and I am getting complaints that its too dry.
Do I buy a misting humidifier and put it in the main room? Any suggestions?
thanks! Jeff in NH.
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Replies
Before humidifying find out if you can turn your ERV down. You can get an AIQ sensor and measure indoor CO2 levels. Around 1000pm is good enough.
There is also nothing wrong with spot humidifier in a bedroom. Watch if your local water has a lot of calcium the ultrasonic ones will make a lot of dust. Not an issue if you have an RO water filter.
thanks, I have taken the speed down two small increments so far from design settings. I do see a tiny bit of condensation now in lower corners of a few windows at current 10 deg outside so I may be at the right place.
As you say I could add a humidifier in bedrooms. I am wondering if putting one in the middle of the main floor (maybe 900 sq ft) mostly open area would make an appreciable difference, say raise rh from 25% to 35% or more. We would also have to see if we get condensation then too - a fine line I guess.
I am not sure your expiations are realistic. When the outdoor temp gets below 10° F condensation on parts of your windows is normal assuming you have a comfortable indoor humidity.
I say turn off your ERV until the indoor humidity exceeds 50%. If you have a drafty old house or even a tight house with few occupants per SQF it will never happen. Adjust the ERV as needed to keep the humidity over 40% and under 52%.
Yes, this plan will piss off the, every building must have an ERV or you will suffer brain damage crowd. I think ventilator are over hyped and only useful in the event of excess winter humidity in cold climates.
Walta
good ideas - I did need the ERV for 2 reasons, this is a tight house with closed cell foam.
1. Winter RH was high and lots of condensation, maybe up to 35 or 40 deg OA, so at the design cfm OA (more or less) I had no condensation at 7 deg OA, lowest noticed temp yet.
Maybe I don't need quite so much OA. (I have dropped it since then, and maybe drop it more).
2. I did have high CO2. We are low now, generally in the 5oos or 600s.
I can try pushing the speed down more, or even (if I get the right timer) set up an hourly schedule.
I do expect the CO2 to get high 1200+ if I shut it off completely however, but maybe somewhere in between is the sweet spot.