Pool Heater Will Not Ignite
Heaters refuse to ignite for a reason — usually one of their own safety interlocks doing exactly what it should. The most common are flow-related, not ignition-related.
Likely Causes
Inadequate flow
The pressure or flow switch will not allow ignition without adequate water movement. A dirty filter is the most common trigger.
Gas supply issue
Closed valve, empty propane, or insufficient gas pressure at the appliance.
Failed igniter or flame sensor
The unit attempts ignition, does not confirm flame, and locks out.
Gas valve failure
No gas delivered even though the sequence starts correctly.
Venting or airflow obstruction
Blocked exhaust, rodent nests and debris inside the cabinet all cause lockouts.
Control board fault
Error codes indicating internal faults or communication problems.
What You Can Safely Check
- Check that the filter is clean and returns are strong
- Confirm gas is on at the supply valve
- Read any displayed error code and write it down
- Look for obvious debris or nesting around the unit
When to Call a Professional
Beyond flow and the gas supply valve, this is a technician's job. Give us the error code when you call — it shortens diagnosis substantially.
Safety: If you smell gas, leave the area and contact your gas utility immediately. Do not attempt repairs.