Dealing with some gas pool heater problems? Check out this troubleshooting guide for solutions
Although they’re not the most energy efficient pool heaters, there’s no denying that gas pool heaters offer top-level performance. When it comes to heating speed, they’re the fastest hands down. And whether it’s sunny out or 35 degrees and cloudy, gas pool heaters keep your pool water heated.
That said, just because gas pool heaters perform well doesn’t mean they come without problems. In fact, you may find yourself dealing with a couple issues just a few years into ownership. And at that point, you can either switch to a heater that’s cheaper to use, or you can bide your time and try to fix up the problems.
This post is all about giving you the most useful gas pool heater troubleshooting tips available. If that sounds good to you, keep reading.
Before doing any tests/troubleshooting, make sure your pool pump is on and sending water to the heater.
How To Troubleshoot Your Gas Pool Heater
Gas pool heater won’t ignite/turn on
Most of the troubleshooting for this problem involves testing individual switches in your pool heater.
Possible cause: Plumbing valves
Solution: Next to your filter and pump, are all of your different multiport valves. Make sure that each one is set to “OPEN” so that water can flow to the heater.
Possible cause: Gas valve
Solution: Check that your heater’s gas valve is fully set to the OPEN position
Possible cause: Gas supply valve
Solution: Whether you use a propane tank or a city gas line, make sure your supply valve is fully open and sending gas to the heater
Possible cause: Pilot light
Solution: If your pilot isn’t lit, check the troubleshooting steps in the next section
Possible cause: Heater switch
Solution: First, check that the switch itself is set to the “ON” position. If the heater doesn’t respond, it’s time to open it up and troubleshoot.
Use a jumper wire to make contact between both metal terminals on the power switch — maintain contact for at least 3 seconds. This temporarily bypasses (or disables) the switch, which allows us to check if the heater will fire without it. So if the heater fires, then we know the switch needs replacement.
Possible cause: Thermostat
Solution: Make sure your thermostat is set to a higher temperature than your pool water. If increasing the temperature makes the heater turn on, then the thermostat is in good condition.
Otherwise, you can use a multimeter to check if the thermostat is receiving power. Or, grab the jumper cable again and do a bypass test. If the bypass makes the heater turn on, the thermostat needs replacement.
Possible cause: High Limit Switch (switch for turning the heater off when it gets too hot)
Solution: Look for the high limit switch on the side of your heater near the outlet manifold. It’s possible that your heater may have two high limit switches. Do the bypass test for each limit switch separately – if bypassing one of the switches causes the heater to fire, replace that switch.
***IMPORTANT: Problems with limit switches are sometimes caused by defective bypass valves (located near inlet), which when not working correctly, can cause the heater to overheat.
Heater’s pilot light won’t ignite
There’s a handful of factors that can stop your pilot light from igniting.
Possible cause: Low gas pressure
Solution: Check that the gas supply valve (propane tank or gas line) is open and sending gas to the heater
Possible cause: Pilot tubing
Solution: Over time, rust, dirt, and other debris can build up within the tubing. So make sure the tubing is in good condition (no cracks, loose connections, etc.), then clear out clogs that exist
Possible cause: Bad ventilation
Solution: Check that your heater has an adequate amount of clear space around it, away from bushes or walls. From there, inspect the heater vents for any debris blockage and clean as needed
Pilot light keeps blowing out
Possible cause: Inadequate gas supply
Solution: If you’re using propane, check that the tank is still full and the valve is open, sending gas to the heater. If you use a city line, check the gauge, then call your supplier and ensure there aren’t any issues on their end.
Possible cause: The wind
Solution: In some cases, windy conditions are too much for the pilot light and blow it out. To prevent this, consider attaching a high wind stack to the heater, which acts as a shield against every strong breeze nature can dish out.
Possible cause: Water runoff
Solution: If there’s water heating your gas heater at the right angle, it can get inside of it and douse the pilot. Common sources of water runoff include sprinklers, rain gutters, and other nearby plumbing.
+For millivolt heaters
Possible cause: Thermopile
Solution: Use a multimeter to test the output of the thermopile. If the output is low or not powering at all, replace the thermopile.
Gas pool heater won’t heat to my desired temperature
Possible cause: Thermostat
Solution: If your thermostat isn’t set to a temperature higher enough than the temperature of the water, then it won’t signal the heater to turn on at all. Raise the thermostat to a temperature at least 5 degrees higher than water
Possible cause: Improper heater size
Solution: Gas pool heaters are ideal for spas and small pools, but they aren’t really designed to heat the average sized swimming pool very efficiently. Therefore it’s possible that your gas pool heater isn’t big enough to keep up with the heat loss of your pool.
Using a solar pool cover is a great temporary solution to this problem, and it reduces heat loss significantly.
Possible cause: Overheating
Solution: If you’ve tested your high limit switches and they’re both working, then your heater may be overheating due to ventilation blockage. Check that the heater’s vents are clear of debris and leaves and that the heater is blowing out the exhaust.
Heater cycles off and on | Why does my pool heater keep shutting off?
Possible cause: Filter/Pump basket
Solution: If your filter is dirty or clogged, then it can’t pump water to your heater at the correct pressure. Fix this common problem by cleaning out the pool filter.
Also, empty out any debris in your skimmer and pump baskets, as both should be clear and clog-free as well.
Resources:
- How To Clean/Replace a Cartridge Filter
- Replace/Clean a Sand Pool Filter
- How To Clean/Replace a DE Filter
Possible cause: Bypass valves (internal and external)
Solution: If the heater’s bypass valve is damaged, then it’ll signal more shutdowns than it needs to. So first, check that the valve is secured in place, and if it’s not, readjust it. If that doesn’t resolve the issue, the bypass valve may need replacement.
Possible cause: Pressure switch
Solution: The pressure switch monitors the PSI of the water coming into the heater, but if it’s not working correctly, it’ll trigger your heater to shut off when it shouldn’t. Use the bypass test on on the switch to see if the heater comes on. If it does, the switch needs replacement.
Possible cause: Heat exchanger
Solution: If you’ve had your gas pool heater for a while, then it’s possible that lime buildup formed inside of the heat exchanger. In this case, replacing the heat exchanger is the easiest solution. But, if you trust your technical abilities, you can also remove the exchanger and clean out the lime buildup by hand.
Gas pool heater is leaking
Things to check and fix:
- Leaking or worn gasket
- Loose connection on pressure switch
- Worn out or missing o-rings
- Loose drain plug
- Damaged heat exchanger
Gas Pool Heater Troubleshooting Codes
Error code: bD
Description:
- Internal fault/power-up issue
- Gas valve sensed as “OFF” issue
- Gas valve sensed as “ON” issue
Error code: HF
Description: Flame present with gas valve “OFF” error
Error code: PF
Description: Electrical supply wiring error
Error code: AO
Description:
- 1.) Blower vacuum switch open error
- 2.) Blower vacuum switch open when expected close error
- 3.) Blower vacuum switch open during post-purge error
Error code: AC
Description: Blower vacuum switch closed when expected open error
Error code: IO
Description: Igniter open error
Error code: SF
Description: Thermistor error
Error code: HS
Description: Water temperature sensing error
Error code: Sb
Description: Keypad button stuck closed error
Error code: IF
Description: Ignition failure error
Error code: CE
Description: Communication error between ignition board and display bard
Error code: LO
Description: Limit string open error
Error code: EE
Description: Ignition control circuit board error
