Pool Heater Won’t Ignite: 12 Common Causes and Fixes
Why Your Pool Heater Refuses to Ignite
You’ve turned the thermostat up. You’ve waited. And waited some more. But your pool heater just sits there, doing absolutely nothing. Sound familiar? This happens to pool owners all the time, and honestly, it’s one of the most frustrating problems you can deal with.
The good news? Most ignition failures come down to a handful of common issues. Some you can fix yourself. Others need professional attention. Either way, knowing what’s going on helps you make smarter decisions about repairs. If you’re dealing with persistent heater problems, reaching out to a Swimming Pool Repair Service Mckinney can save you hours of guesswork.
Let’s walk through the most common reasons your heater won’t fire up and what you can actually do about each one.
Gas Supply Problems
The Valve Might Be Off
I know this sounds obvious. But you’d be surprised how often the gas valve gets bumped or accidentally turned off. Check the valve on the gas line leading to your heater. It should be parallel to the pipe when open. If it’s perpendicular, no gas is flowing.
Low Gas Pressure
Sometimes the problem isn’t your heater at all. Your gas company might have reduced pressure in your area, or there could be a partial blockage in the line. If other gas appliances in your home are working fine, this probably isn’t the issue. But if everything seems weaker than usual, call your gas provider.
Empty Propane Tank
Running a propane heater? Tanks run out. It happens. Check your gauge. And remember—propane gauges aren’t always accurate when temperatures drop, so the reading might show more fuel than you actually have.
Pilot Light and Ignition Issues
Pilot Won’t Stay Lit
Older heaters use standing pilot lights. If yours keeps going out, the thermocouple is probably failing. This little sensor detects whether the pilot is lit and tells the gas valve to open. When it goes bad, the valve stays shut even when the pilot is burning just fine.
According to Wikipedia’s overview of gas heaters, thermocouples are safety devices that prevent gas leaks when no flame is present. They’re inexpensive parts but can be tricky to replace without experience.
Electronic Ignition Failure
Newer heaters use electronic ignition systems instead of standing pilots. You might hear clicking sounds but see no flame. The igniter could be worn out, cracked, or just dirty. Sometimes a simple cleaning with fine sandpaper gets it working again.
Water Flow Problems
Pressure Switch Won’t Engage
Your heater has a pressure switch that confirms water is flowing before allowing ignition. No water flow means no heat. This prevents the heater from running dry and damaging itself.
Check for clogged filters, closed valves, or a pump that’s not running properly. Even partially blocked skimmer baskets can reduce flow enough to trip the switch.
Clogged Heat Exchanger
Scale buildup inside the heat exchanger restricts water flow and causes all sorts of problems. If you’ve got hard water and haven’t had your heater serviced in a while, this could be your culprit. The buildup needs to be chemically cleaned by someone who knows what they’re doing.
Sensor and Control Problems
Faulty Temperature Sensor
The temperature sensor tells your heater how warm the water is. When it malfunctions, it might tell the heater that the water is already at the target temperature—even when it’s freezing cold. The heater thinks it doesn’t need to fire up.
For reliable diagnosis and repair of these sensor issues, Deck O Art recommends having a certified technician test the sensor’s resistance readings against manufacturer specifications.
Control Board Failure
Modern heaters rely on circuit boards to coordinate everything. Power surges, moisture, and plain old age can fry these boards. Signs include error codes that don’t make sense, random shutoffs, or a heater that does absolutely nothing when you adjust settings.
Replacement boards aren’t cheap, and installing them wrong can create bigger problems. This is definitely professional territory.
Ventilation and Exhaust Concerns
Blocked Exhaust Vent
Birds love building nests in exhaust vents. Leaves pile up. Debris accumulates. When exhaust can’t escape properly, safety sensors prevent ignition to protect against carbon monoxide buildup. Check your vent pipe and clear any obstructions.
Wind Interference
Strong winds can blow out pilots or interfere with ignition. If your heater only fails on windy days, consider adding a wind guard. Some heaters have built-in wind-resistant features, but older models often don’t.
Burner and Combustion Issues
Clogged Burner Orifices
Spider webs. Rust. Debris. Stuff gets into burner orifices and blocks gas from flowing evenly. You might see yellow or orange flames instead of clean blue ones, or flames that appear uneven and weak. Cleaning requires removing burners and carefully clearing each orifice.
Corroded Burner Assembly
Pool equipment sits outside in all kinds of weather. Over time, burner assemblies corrode. Severely corroded burners don’t distribute gas properly and can become safety hazards. If your burners look rough, replacement is usually the better option compared to trying to nurse them along.
When Repair Makes Sense vs. Replacement
Here’s a question worth asking: how old is your heater? Pool heaters typically last 8-12 years with proper maintenance. If yours is pushing that limit and needs expensive repairs, putting that money toward a new unit often makes more financial sense.
Newer heaters are way more efficient too. A high-efficiency model could cut your heating costs by 20-30 percent compared to an older unit. That adds up fast over a swimming season.
But if your heater is relatively young and the repair is straightforward—like a thermocouple or pressure switch—fixing it is probably the smart move. Swimming Pool Repair Service Mckinney professionals can help you weigh the costs and make the right call for your situation.
For more helpful resources on pool equipment maintenance, you can explore additional information that covers seasonal care tips.
Frequently Asked Questions
How do I know if my pool heater problem needs professional repair?
If you’ve checked the obvious stuff—gas valve, pilot light, water flow—and everything seems fine, it’s time to call someone. Also, anything involving gas lines, control boards, or internal components should really be handled by pros. Safety first.
Can I test my pool heater’s igniter myself?
You can visually inspect it for cracks or heavy corrosion. Some igniters can be tested with a multimeter if you know what readings to expect. But honestly, if you’re not comfortable with electrical testing, skip it and get professional help.
Why does my pool heater work sometimes but not others?
Intermittent problems usually point to failing components that haven’t completely died yet. Temperature sensors, pressure switches, and control boards often behave this way before total failure. Loose electrical connections can also cause this.
How much does pool heater repair typically cost?
Simple fixes like thermocouple replacement might run $100-200 including labor. More complex repairs involving control boards or heat exchangers can range from $300-800. Full heater replacement starts around $1,500 and goes up from there depending on size and type.
Should I cover my pool heater during winter?
Covering protects against debris, animal nesting, and weather damage. Just make sure the cover allows ventilation and remove it completely before operating the heater. Trapped moisture can actually cause more problems than exposure in some cases.