RV water heater electric and propane troubleshooting guide

Identify the failure pattern

Does the heater fail on propane only, electric only, both sources, or does it heat but deliver lukewarm water? The answer changes the path. Propane-only failure points to gas supply, ignition and flame sense. Electric-only failure points to 120V power, switches, high-limit protection and the element. Lukewarm water often points to bypass or cross-mixing.

Confirm tank fill and plumbing position

Open a hot faucet with heat off until water flows steadily. Then confirm bypass valves are in normal use position. On many RVs the cold inlet and hot outlet are open while the bypass line is closed, but handle orientation varies by installation.

Propane mode checks

Confirm propane supply, slow-open cylinder valves, appliance lockout reset procedure and exterior burner area condition. A click with no flame points to ignition/pro gas path; flame that lights then drops out points to flame sense, ground or board logic. Soot or delayed ignition is a professional-service sign.

Electric mode checks

Confirm the correct electric switch, the breaker, any outside heater switch and 120V supply. If the tank was dry-fired, suspect the electric element. Testing the element requires power off, pressure relieved, access to terminals and meter checks for resistance and short-to-ground.

High-limit and thermostat clues

Reset buttons may restore operation after an over-temperature trip, but repeat trips need diagnosis. A stuck thermostat, poor contact, scale, wiring fault or control issue can create unsafe temperature behavior.

When to stop

Stop for propane odor, soot, burned wiring, repeated breaker trips, tank leaks, pressure-relief discharge that does not resolve, or any live electrical testing you are not trained to perform.