A pool heater will not light
A pool heater that will not light is often short on water flow, set so it is not calling for heat, or showing a code. Read the code and the rating plate. Leave the burner area closed.
· 5 min read
Do not open the burner area. Gas valves inside the heater, and the wiring on the control board, are a technician's job.
Start with water flow
A heater that clicks and never lights, or lights and then shuts off, often does not have enough water moving through it. The flow switch or pressure switch is doing that on purpose. Look at the pump lid and the filter pressure first. Air in the pot is covered in why a pool pump loses prime. Pressure well above the clean baseline is covered in how to clean a pool filter.
Confirm the heater's thermostat is set above the water temperature, and that a remote or an external switch is not holding it off. A heater left off looks like a failed heater when you are standing at the equipment pad.
Read the code, then the plate
The display or the lights on the control are the diagnosis. Write the code down exactly. The manual for that model maps the code to flow, ignition, or a limit. Guessing from the symptom and replacing a board is how people buy the wrong part.
The rating plate has the brand, model, serial, BTU input, and whether the heater is built for natural gas or propane. Those two fuels are not the same part. What to copy is in how to read a pool heater rating plate.
Leave the burner closed
Do not remove the burner tray, adjust a gas valve inside the cabinet, or bypass a pressure switch to force it to fire. A heater that runs on weak flow overheats the exchanger. If the code points at ignition or the gas supply, and the shutoff serving the heater is already open, the next step is a technician who works on that brand.
When the plate says you need a part, match it to that model. Gas heaters are in equipment. Unions and gauges on the water side are in plumbing.
Questions
Why does my pool heater click but not light?
Often the water flow is too low for the pressure switch, the thermostat is not calling for heat, or the control is showing an ignition code. Check the pump, the filter pressure, and the code on the display before you replace a part.
Can I convert a natural gas pool heater to propane?
Only with the conversion the manufacturer specifies for that model. The rating plate says which fuel it was built for. A natural gas heater and a propane heater are not the same part.
What should I photograph before I order a heater part?
The rating plate: brand, model, serial, BTU input, and fuel. Add a photo of the error code if the display is showing one. An internal part number still has to match that model.