I recently had a new HVAC system installed in my attic. It is a Carrier heat pump system with a propane furnace backup. The furnace is a 58MVB120-120 high efficiency unit. After the installation was done, I found out that these high efficiency furnaces are not recommended in the attic because the condensate trap can freeze. The contractor has put heat tape on the condensate trap to keep it from freezing. He also plans to put a foam board box around the furnace to help keep the condensate trap from freezing.
In the short time that this furnace has run during cold nights, it has used a LOT of propane. I have asked the contractor to come and check this out. Does anyone know if putting this high-efficiency furnace in the cold attic makes it run less efficiently? Other than the risk of the condensate trap freezing, does anyone see any other problems with putting the high efficiency furnace in the cold attic?
I appreciate any feedback.