3 Things to Check When Your Pool Heater Won't Light

Clean or backwash your filter first A dirty filter restricts water flow, triggering the pressure switch that prevents the heater from igniting. Clean the filter and ensure the pump is running strong before troubleshooting further.

Confirm the gas supply is on Check that the gas valve to the heater is fully open—it can get bumped closed by kids or landscapers. If you use propane, verify you haven’t run out.

Call a pro if flow and gas are fine A bad igniter, flame sensor, or control board is possible but less common than flow or gas issues. If you’ve ruled those out, it’s time for someone with spare parts.