I have a built a home (midwest) for a client with a hydronic radiant floor system and a forced air handler for fresh air with a HRV system (carrier), air cleaning (space guard), humidification (aprilaire, winter only) and AC. The problem is that the house can not get above 20% plus humidity in the winter months. The client is concerned with the shrinkage in his millwork, hardwood floors and furniture. We have run hot water to the humidifiers which has help a little, but it is still very dry. What should be the optimum humidity level for a home? Also, does anyone have any ideas on how to increase the humidity level.
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You're losing too much heated air and replacing it with (cold) dry air. Start with weatherization principles. I'll bet that somewhere is a big heat loss source: ceiling cans into the attic, unintended chases. Etc. Plan on spending up to a day just looking the place over, very closely.
And how is that humidity being measured? Consumer humidly gauge? Humidistat on the humidifier? Or something that can actually be trusted?
No more than 40% humidity, less in very cold weather.
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Jack,
The optimum range of relative humidity for human comfort is 30% to 60%.
You will need to provide more information on mechanical specifics:
-how is the combustion air supplied to the boiler?
-how is the boiler vented?
-same for the domestic water heater
-does the HRV transfer humidity or just heat?
-how much supply/exhaust does the HRV provide?
-how effective is the HRV?
You will find it hard to humidify cold air. An AprilAire type of humidifier, powered or bypass, works by passing hot (like 120 plus degF) furnace discharge air over a wet evaporative media. Is is maginally effective with hot air. Air coming from the HRV will be relatively cold, unless a heating coil has been installed.
Assuming there is no major air leakage problems, the HRV supply to the space is unheated and the boiler is not steam, there are a few ways to increase the rh in the space. Heat the air before humidifying or get an electric steam humidifier. If the HRV is sensible only, another option is to replace it with one that transfers sensible and latent energy (i.e. humidity).