What can be done about uneven heating in fifth wheel?

By Chris Dougherty
Chris Dougherty is a certified RV technician. Here is a letter he received from a reader while he was serving as RVtravel.com’s technical editor.

thermometer humorDear Chris,
We have the same problem with our Crossroads 34′ fifth wheel as we had with our Jayco 30′. The furnace (which is located near the steps going up to the front) keeps the bedroom and bathroom toasty, but the living area is still cold. Would covering certain vents to force the heat to the back cause an unsafe situation? If so, is there any way to get more heat to the rear of the unit? —Astrid

Dear Astrid,
This is a common issue with fifth wheels. The answer and the fix relate to the simple fact that heat rises. As the furnace dispenses hot air from the registers, the warm air rises to the highest point, and the cooler air falls to the floor. The problem is the floor of the upper bedroom and bathroom (or whatever room is in the higher level of the fifth wheel) is much higher than the downstairs floor. So, the warm air layers from the ceiling down.

What enhances this problem is that most of the ‘lower end’ fifth wheels have only a single zone for heat and air conditioning. The thermostat is usually located in a ‘central’ spot which will ‘average’ the temperature between upstairs and down. However, as I have found in my 5’er, and I assume you have as well, that average just doesn’t work when the temperatures outside start to get extreme. In this case, the upstairs gets downright warm, while the downstairs gets cool.

If it were a two-zone system, the fix would be easy: keep the door to the upstairs closed. The downstairs zone would stay at its set temperature as would the upstairs. But since it’s one zone, it requires some ingenuity to keep ahead.

Closing off registers in an RV is NEVER recommended. The reason is because the furnace is designed to work properly with a certain minimum amount of airflow to make it more efficient, and to keep it from overheating. Closing off registers reduces airflow and can lead to furnace overheating and cycling, as well as overheating of other components like duct work and other registers.

A small electric fan is one option to help circulate the warmer air from upstairs back downstairs. An RV ceiling fan would be another option.