1> The contractor installed it in the return plenum with cold water supply. I have a 4500 sq ft home. Will it keep the RH >40%?
2> I have noticed that the blower fan does not come on. Should it come on whenever the humidifier is on?
In order to create humidity we need three things…..
2. Air flow
3. Heat to evaporate the water.
If you put the 700 on the cold air return with cold water, you are missing a source of heat to evaporate the water. Mounting the unit here is ok… just run hot water to it or you will not get the humidity you are expecting.
You mention that a fan does not come on when creating humidity… which fan are you referring to?
In order for the humidifier to operate correctly, the furnace blower needs to be on. Also, the fan inside the furnace should be going as the water starts to flow through the humidifier. So, yes, the blower should be on.
Please let us know if you have any further questions.