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Thread: HRV issues

  1. #1

    HRV issues

    OK, I had the furnace tech stop back and added a relay and rewired furnace blower to run at a slower speed (same speed as when furnace normally runs) only when the HRV is on. Everything went well, except now the HRV has been running constantly for 1 1/2 days and it will not get the humidity below 45% in the house. The HRV is a 200cfm unit on high speed and the house is 2000sq ft plus the basement. What could the issue be? I need some info so I can tell the HVAC people.

  2. #2
    Join Date
    Jun 2003
    Madison, WI/Cape Coral, FL
    The indoor %RH is determined by the outdoor dew point, amount of fresh air, and the amount of moisture added by the occupants. During typical fall weather, 45%RH is ideal. As long as the none of the indoor surfaces are dripping moisture, relax. 200 cfm of fresh air is much more than you need to purge indoor pollutants. 100 cfm when occupied is plenty plus the natural infiltration get upto 150 cfm. Overventilating with the HRV and the furnace fan operating is cost you much more than you will save. Most homes get more than enough fresh during cold windy weather. This is sad. Get a CO2 meter is you nervous about the amount of ventilation you really need. Cut back until you see some moisture on the coldest windows. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  3. #3
    Hi teddy bear, for years I've battled condensation on windows(extremely tight house). Humidity in my house was always high(40% inside humidity during -20 degree temps outside. In the past I had the contractor come over and install a Skuttle and that didn't help the moisture problems. I finally decided to go the route of a HRV. So what you are saying is the colder it gets outside the HRV will compensate and push the humidity lower? My wall control has a variable control for humidity %. Thanks

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