First of all, thanks for all the replies. Mine is currently installed in front of the condenser above the furnace and a 6" duct comes out of it that connects to the return air duct. I assume this 6" duct is where the humidifier feeds humidity back to the outgoing heated air. I was just wondering if this is the correct installation as the air in the house is still dry as measured through a humidistat. I was concerned as the return duct then feeds into an electronic air filter, i.e. 6" duct from humidifier -> return duct -> air filter. If the electronic air filter is supposed to trap small particles, won't this setup trap the water droplets produced by the humidifier? Thanks again for all help.