I had posted the following message in alt.hvac and it was recommended that I check with the folks here.
I hired a contractor to replace my heat pump and forced air blower. To make life a little sweeter I requested that an in-duct humidifier be added. The HVAC ducting on the supply side of my blower has two branches. One branch serves the basement and the kitchen area that makes up about half of the first floor living area. The second branch serves the other half of the first floor and the entire second floor living area. The contractor elected to install the humidifier in the duct serving the basement and kitchen. Since this installation I noticed that I now have mold growing in the basement and that the relative humidity in the second floor living areas could only reach about 23%. It looked to me that they installed the humidifier in the wrong branch. I wouldn't think anyone would want to have humid air in a basement and I don't think a kitchen area needs humidification. Essentially about 75% of the living areas were not being serviced by the humidifier. Following my complaint, the contractor told me that the installation they performed was correct. The rationale given to me was that since hot air rises, it would have been improper to have the humidifier installed in the duct branch serving the second floor.
I'd really appreciate hearing back from someone with some expertise on the subject. Am I just an unreasonable customer or did the contractor just give an excuse for a bad installation.