RV furnaces use one or more remote temperature sensors, depending of the size of the RV, to determine the temperature in specific climate zones within the vehicle. These sensors relay information to the thermostat, which in turn operates the furnace in each designated area.
In a typical home environment, the heating system has one thermostat with a built-in heat sensor. This provides a single point of control for the heating of the entire house, but in some older models leaves certain rooms hotter or colder than others. An RV furnace breaks the vehicle up into smaller sections and uses smaller heating systems to control each section. This is done to reduce costs and minimize use of propane when the furnace is running.
To identify the remote heating sensors, look for a small black or white plastic circle mounted to the walls. One will usually be in the main cabin of the RV, with others in the bedrooms or near the driver's seat. The area surrounding these sensors plays a huge role in determining the temperature of the RV. For example, if one sensor is near a door or a window, outside air can come in and cause the sensor to think that the internal temperature is colder than it actually is.