The RV Furnace

The air intakes (for the fan that supplies return air to the furnace blower) are located on either side and the top of the metal furnace housing. These air intake slots draw air from the surrounding area and the blower fan forces this air past the sealed combustion chamber in the furnace and on to the warm air duct work.

If this intake air flow is restricted, (with loose plastic bags, aforementioned cookie sheets, etc.) the fan motor speeds up. (the same effect is observed when the intake hose of a vacuum cleaner is plugged off).

There is a separate combustion air system, sealed from the inside of the coach, that feeds fresh air to the burner assembly inside the furnace. This system draws in outside air to allow the proper combustion of the fuel gas and then forces the exhaust products out again. The fan for this system is powered by the same furnace motor that runs the blower, therefor it speeds up at the same rate.

The increased air flow in the combustion chamber alters the burn characteristics of the flame - producing a leaner, hotter flame. This overheating can lead to failure of the furnace safety devices, damage to the electronic components of some models or in the worse case a cracked combustion chamber. Exhaust products, including CARBON MONOXIDE, will now be forced into the living area !!!! CO is odorless, colorless and extremely toxic - a silent killer.

Please check your furnace compartment for air flow restrictions.

If you have any doubts or concerns regarding your furnace's condition, have it inspected by a licensed, qualified RV gas technician.

A carbon monoxide detector installed in your unit is a very inexpensive life insurance policy.

Troubleshooting: 

DSI RV Furnace Troubleshooting