Hi all, The furnace in my '76 Sovereign is working well now but I have a question. Does it recirculate the interior air (like my house) by way of a return air duct or opening or does it continually pull in outside air or what?
The heated air is completely separate from the burner air in the furnace. Air for the combustion section is pulled from the outside and then vented outside as well. The interior air is reheated and recirculated inside the trailer.
Richard WBCCI President 2016-2017
I have the under sink cabinet pretty much apart due to removing the tambour which wasn't sliding all the way open. Looking around under there, The outgoing ductwork is easy to see and understand but I don't see how the interior air gets back into the unit to be reheated and recirculated. It works fine but I'm curious and want to know how stuff works :-)
On my trailer, the air duct is to the left of the heater. The heater is under the stove. I can see the intake duct from inside the front door entry. It is the only vent not throwing hot air, so I guess it is the intake??
Well I ended up tearing out the whole front of the cabinets because I decided since the tambour was sticking I'll build a regular cabinet front with nice wood doors. Anyway, when I took out the under sink shelf and the furnace was completely exposed, I could see the return(s) easily. There are two openings in the furnace box approx. 2" X 10". One on the top and one on the side facing the under sink area. The one on the top was completely blocked by the shelf which was laying flat on top of the furnace box and completely covering that return opening. Running the furnace with both openings now free the unit puts out a lot more air at the heat ducts and the exhaust is much cooler! So I'm happy that I pulled everything apart! Now to build new facias and doors.
The return air is not ducted but is expected to find its way through the cabinetry to the back of the furnace. That is where the blower is and you'll note the ventilation holes near the rear of the furnace to accept the air that is blown out through the ducts.
I don't know what it is about restricting air flow through the furnace but I have even encountered some whose ductwork didn't provide for sufficient flow to keep the overheat switch quiet. Keeping the area around the furnace clear is one way to make sure that the return air part of the loop isn't hindered too much.