Why Is My Pool Heater Not Working?Updated a month ago

A malfunctioning pool heater can put a chill on your swim plans—especially during winters or cooler evenings. From ignition issues to flow errors, here’s how to diagnose common problems and get your heater humming again.

Common Causes & Fixes

1. No Power or Ignition Failure

Symptoms: Heater won’t turn on, or pilot light won’t stay lit.
Fix:

• Check power supply: Ensure the heater is plugged in, and circuit breakers are on.

• Gas heaters: Verify gas valve is open and pilot light is clean (use a soft brush).

• Error codes: Refer to the manual (e.g., “Ignition Lockout” may mean blocked vents or faulty thermocouple).

2. Low Water Flow

Symptoms: Heater shuts off automatically or displays “Flow” error.
Fix:

• Clean pool filter (clogs reduce flow).

• Check pump operation: Ensure it’s running and primes properly.

• Inspect heater bypass valve: Adjust to allow full flow through the unit.

3. Thermostat Issues

Symptoms: Heater runs but doesn’t warm the water.
Fix:

• Check thermostat settings: Ensure it’s set above the current water temperature.

• Test thermistor (temperature sensor) with a multimeter—replace if faulty.

• For solar heaters: Clean panels from debris or calcium buildup.

4. Blocked or Dirty Heat Exchanger

Symptoms: Reduced heating efficiency, strange noises.
Fix:

• Gas heaters: Remove debris from burners and flue.

• Electric/Solar heaters: Descale heat exchanger with vinegar solution (for lime/calcium buildup).

• Saltwater pools: Inspect for corrosion and flush with fresh water monthly.

5. Airflow Restrictions

Symptoms: Heater overheats or emits smoky smells.
Fix:

• Clear leaves, spider webs, or nests from vents and exhaust pipes.

• Ensure 10–15cm clearance around the heater for ventilation.

Troubleshooting Flowchart

1. Heater won’t start → Check power/gas supply, reset breaker.

2. Heater starts but stops → Clean filter, check water flow.

3. Weak/no heat → Test thermostat, inspect heat exchanger.

4. Error codes → Consult manual or call a pro.

Preventative Maintenance Tips

• Service annually: Gas heaters need licenced pros to check for leaks or carbon monoxide risks.

• Winterise: Drain water from solar panels or heat pumps in frost-prone areas.

• Use a cover: Reduces heater workload by retaining heat overnight.

When to Call a Pro

• Gas leaks (smell rotten eggs? Shut off gas and evacuate!).

• Electrical faults beyond basic DIY (e.g., fried control boards).

• Warranty-covered repairs: DIY attempts might void coverage.

Final Tip: A little upkeep goes a long way—clean filters, clear vents, and annual servicing keep your heater reliable.