According to the Coachmen website, the 37 foot Encounter can come with either one 37,000 BTU heater, or two 20,000 BTU heaters. So first you have to see which one you have. You should be able to tell by looking at the outside of your coach. The furnaces should have a metal door covering them with a round exhaust port in the door. If you find two of those you have two heaters. If you find one, then you have to figure out if there are two heaters in the same compartment or not. My two heaters are on opposite ends of the coach so I have one in the front and one in the back.