Wall Mounted Furnace Unit: Shall one use a heat pump and remove electric coils to represent a wall mounted furnace? Any recommendations on modeling a wall furnace such as this? A Williams 3509822 Gas Fired Wall Furnace rated at 35,000 BTU https://www.alpinehomeair.com/viewproduct.cfm?productID=453069474&linkfrom=froogle&gclid=CK-S8-26zdMCFYZffgodfzYE_A