Why is a load calculation necessary?
Manual J load calculation should always be used to size heating and cooling systems. It is mandated by local codes and the DOE (Department of Energy) Manual J calculates the heat loss and gain through walls, windows, floors, infiltration and the roof. It also accounts for internal heat loads such as people, appliances, electronics, etc. No other method does this. Hamstra uses Manual J load calculation to size all of the systems we install. The design conditions that Hamstra uses for Tucson are: 104 degrees Outdoor DB (Dry bulb) with 75 degrees Indoor DB, 67 degrees Indoor WB (wet bulb). These design conditions/standards are per the model energy code. Using any other method than Manual J is incorrect and should be completely avoided.
