RV Water Heater: LP Gas Mode
The most basic model gas RV water heater has a pilot light which must be lit manually with a match or sparking device.
There is a manual valve that must be set to the “Pilot” position to light the pilot and then you move the valve to a Run position for continued operation.
Once the pilot light is lit and the heater control circuit board detects a flame at the flame sensor, the gas mode thermostat starts and stops the flow of LP gas to the burner, where it is ignited by the pilot flame.
There is no need to relight the pilot each time more hot water is needed.
If the pilot goes out, no flame is detected and no gas is allowed to flow, preventing any danger from leaking LP gas. When you no longer need to have hot water available, turn the Pilot Control switch to Off and the heater shuts down.
Most modern RV water heaters are the DSI (Direct Spark Ignition) type, which has no pilot light. When you switch on the water heater in LP Gas mode, the gas mode thermostat will call for it to be heated as needed.
When heating is called for, the heater control circuit board opens the gas valve and activates the igniter, making a spark at the front of the heater’s gas burner tube, and [hopefully] igniting the flame.
At the same time, the control board starts sensing for a flame [the igniter doubles as a flame sensor]. When the burner flame is sensed, the ignition sequence is complete.
If no flame is detected after a preset time (about 15 seconds), the gas valve is closed, the igniter is turned off, and the system “locks out,” meaning it won’t allow another attempt at restarting until the system is reset by turning it off and on again.
Usually a red indicator light will show at the LP Gas Mode switch if the heater fails to light when needed.
While you can run a DSI RV water heater in LP Gas Mode while driving, this is generally not necessary since it heats up within 20-30 minutes after it is turned on anyway.
A Manual Pilot type of water heater usually does not work while driving – the wind blows the pilot light out. Few RV’ers leave their water heater on while traveling – it’s just a waste of fuel.
The MotorAid system is conceptually quite simple.
Water from the motorhome’s engine cooling system is circulated through tubes embedded in the water heater. Whenever the engine is at its normal operating temperature, the water in the tank is being heated by the waste heat from the engine.
This provides heated water as well as assisting in cooling the engine.
RV Water Heater Maintenance
Your RV water heater requires very little care in normal use.
The Electric Mode is essentially maintenance free, and the LP Gas mode needs only an annual cleaning of the burner tube to remove rust flakes, spider webs, etc.
A vacuum cleaner nozzle on the tube is usually sufficient. However, when you store the RV for long periods you should drain the tank (see your water heater’s owners manual) and, if sub-freezing weather is expected, winterize the associated water lines.
The RV’s heater plumbing usually has a bypass valve to assist in winterizing.
The heater bypass and winterizing procedures are part of the general RV maintenance information and not covered in the WH manual.
See more about general RV winterizing.
See more about RV water heater repair.