Pool Heater Not Igniting? Here's Why (+ How to Fix) (2024)

Pool heaters occasionally experience ignition failures that prevent them from warming the water. If they go unchecked, they could overheat and overload other parts of the heater. It’s best to diagnose and fix the heater’s ignition issues as quickly as possible to prevent expensive repairs and replacements.

Your pool heater isn’t igniting for these reasons:

• Broken ignitor
• Damaged pilot light tubing
• Not enough gas flow
• Malfunctioning thermostat
• Bad ventilation
• Too much moisture in the heater

In this article, I’ll discuss why your heater isn’t igniting and what you can do about it. I’ll also provide a few preventative tips. Enjoy!

Broken Ignitor

A broken ignitor is one of the main reasons your pool heater won’t work properly. It prevents the heater from creating a flame, rendering it useless. The damaged ignitor can increase the gas flow in the heater, causing gas leaks. Your heater will likely have an error code labeled in the manufacturer’s guidelines.

How to Fix

Replace the ignitor with these steps:

1. Turn off the electricity and gas going to the pool heater.
2. Open the faceplate of the heater, then locate the pronged ignitor.
3. Remove the retaining bracket and screws, then disconnect the ignitor from the motherboard’s wires.
4. Contact the manufacturer for a like-for-like ignitor part number, then attach it to the motherboard’s wires.
5. Secure the retaining bracket and screws, then close the heater’s faceplate.
6. Turn on the heater and adjust the heat to your desired temperature.

Damaged Pilot Light Tubing

The pilot light tubing protects the flame in the heater. If the tubing is damaged, the pilot light can’t stay lit. If you have a saltwater pool, it’s important to place the salt cell after the heater to prevent inevitable corrosion. The highly saline water can deteriorate the heater’s components, damaging the tubing, rusting the control board, and so on.

How to Fix

If the pilot light tubing is damaged, it needs to be replaced. This insulating tubing is unique to the heater. Contact the manufacturer to ask for a spare set of tubing. Unfortunately, most pool heater manufacturers sell the tubing with the pilot light, so it’s rare to get the tubing by itself. Connect the new pilot light by removing the retaining screws and clipping it to the heater.

If you can replace the tubing without changing the pilot light, simply cut out the old tubing and slide the new tubing over the pilot light. This sleeve protects it from water damage and rust.

Not Enough Gas Flow

A lack of gas flow can cause your heater to malfunction. If there’s not enough gas going to the ignitor, it’ll signal an error code to the control board. This code prevents the heater from igniting because the spark can’t create a flame. This common issue happens when there’s a clog in the gas line, or the valve is slightly closed.

How to Fix

If you think there’s not enough gas flow going through the pool heater, try these tips:

• Mix water with dish soap, then pour the solution over each of the gas pipe connections. If it bubbles excessively, there’s a gas leak. Contact a licensed professional to fix the leak after turning off the gas line going to the heater.
• If the gas line isn’t leaking, open the valve all the way to increase the flow going to the pool heater. You might need to contact a professional to remove rust, dust, and debris from the galvanized pipe.

Faulty Thermostat

Your pool heater’s thermostat tells the ignitor when to heat the pool. If the thermostat is broken, it won’t turn on the ignitor. Thermostats can be damaged by acidic water, corrosive salinity, long-term usage, and the elements. Make sure you know how to raise your pool’s pH before installing a heater.

How to Fix

Replacing the thermostat is the best way to get your heater back on track. A faulty thermostat limits the ignitor, preventing it from heating the water and checking the error codes.

Here’s how you can replace the thermostat:

1. Turn off the electricity and gas going to the pool heater.
2. Locate the thermostat going into the plumbing (it’s a thin metal sensor on the back of the heater behind the faceplate).
3. Trace the wires going from the thermostat to the motherboard and disconnect them on both ends.
4. Unscrew the thermostat and get ready for the water to flow out of the plumbing.
5. Quickly screw the new thermostat in its place to stop the leak, then connect the wires to the previous thermostat’s nodes on the motherboard.
6. Secure the faceplate, open the gas valve, and start the heater.

Review this helpful video guide for more information:

Poor Heating Ventilation

Bad ventilation prevents your heater from igniting because there’s not enough air getting to the pilot light. The ignitor needs gas and air to light the flame. Clogged debris, warped parts, and various items blocking the vents will prevent the heater from warming the water. The ignitor will be useless until the vents are cleared.

How to Fix

Here’s what you can do:

• Clean the vents with compressed air, paper towels, and abrasive sponges.
• Vent the pool heater with a chimney if it’s in a pool house (contact a local professional to prevent warranty issues).
• Remove cobwebs and debris throughout the inside of the heater annually.

Excess Moisture in the Heater

Pool heaters shouldn’t have water anywhere other than the plumbing. Internal leaks and strong rainstorms can rust the internal components, including the ignitor. If the pilot light, ignitor, or control board corrodes, the heater can’t ignite. Make sure you seal the leaks as quickly as possible to prevent further damage.

How to Fix

All corroded components need to be replaced; otherwise, you can dry the inside of the heater and fix the plumbing leak. Check the unions and pipes to ensure they’re not leaking. Turn off the power going to the heater and cover it with a tarp during heavy rainstorms to keep the water out of the control board.