Originally Posted by
voleye
We have the same thing all the time here. If Im using electric as the back up I like to size the first stage to do as close to 100% of the cooling load, and try to get the second stage as close to 100% as I can. If I have a gas backup heating system, then I don't mind keeping the loop short and sizing closer to the cooling load with a 95% variable speed backup. My house for example. One zone is 25,000 cooling and 44,000 in heat. With a 3 ton Climatemaster Tranquality 27 I do 99.9% of the heating with the geo and don't use the electric back up very often at all. The only problem I have with humidity is I have to have the humidifier on in the heat of the summer. It actually drops the humidity down under 40% and its too dry.