Stop
If you smell gas near a gas pool heater, do not attempt repairs; turn off the gas supply, leave the area, and call your gas utility or a professional.
Symptoms
- Water temperature stays the same despite the heater running
- Heater displays an error code or won't ignite
- Heater short cycles on and off
Likely causes
- CommonDirty filter restricting water flow to the heaterHeaters have flow switches that prevent operation if flow is too low.
- CommonThermostat set below current water temperatureA simple setting oversight is often the cause of a heater seeming not to work.
- PossibleGas supply or ignition issue (gas heaters)A closed gas valve, empty propane tank, or failed igniter prevents heating.
- PossibleTripped breaker or wiring issue (electric heat pump)Heat pump heaters need consistent power and can trip on their own protections.
What to do
- Confirm the thermostat setting is above the current water temperature and the heater is switched to heat mode.
- Clean or backwash the filter to ensure adequate water flow to the heater.
- Check any visible error code on the heater's display and reference the manufacturer's code list.
- For gas heaters, confirm the gas supply valve is open and, for propane, that the tank isn't empty.
- For heat pumps, check that outdoor air temperature is within the unit's effective operating range, since most struggle below 50°F.
- Reset the heater according to manufacturer instructions and check breakers for electric models.
Tools and parts
- Filter cleaning supplies
- Owner's manual (for error codes)
Pool heater igniterSearch: “pool heater igniter replacement”
Pool heater thermostatSearch: “pool heater thermostat control”
When to call a pro
Gas heater ignition systems and heat pump refrigerant issues should be handled by a licensed pool equipment technician.
Safety
Stop
If you smell gas near a gas pool heater, do not attempt repairs; turn off the gas supply, leave the area, and call your gas utility or a professional.