Gas Pool Heater Troubleshooting

If your gas pool heater breaks down, you should have it looked at by a professional. Whether fuelled by natural gas or propane, the device can be quite hazardous. In some cases, however, the problems with your swimming pool heating system can be quite manageable if handled with care. 

Some of the most common problems that you might encounter with your pool heating system are listed below.

Pilot Light

If the pilot light for your pool heater isn’t lighting, it could be due to low gas pressure, an inadequate supply or poor ventilation. Check that there is gas in the gas tank and that it is turned on. Then check to see that pilot tubing isn’t clogged. 


If your gas pool heater is not reaching the right temperature, make sure the thermostat isn’t set too low. You should also check the gas supply as a low amount of gas being fed to the heating system could also cause problems. 


If your pool heater is leaking water, it was most likely caused by frost and thawing during the winter months. The winter freeze could have resulted in a gasket leaking, or there could be a loose connection to the pressure switch. You are most likely to notice the leaking in spring. 

However, if your pool heater only seems to leak when the burner is on, this may be caused from condensation. You should therefore check to make sure that the internal bypass is working properly and that the heat exchanger is not filling with soot. 


If you can hear a whistling sound from you gas pool heater, this is most likely to be caused by low gas pressure. Check the level of gas in the tank and refill as directed in your manual. 

Lime Scale

Your swimming pool water is full of dissolved minerals such as calcium, magnesium and phosphates. When these are heated through the heater, it causes a chemical reaction that ultimately turns them into solids. These solid minerals are known as lime scale. 

When lime scale builds up around the heat exchanger, it prevents the heat from getting to the water. This results in more money being spent trying to heat the swimming pool. To avoid lime scale buildup, purchase a swimming pool de-scaler. 

Black Smoke

If your pool heater is either black on the top or producing black smoke when it is running,  this is due to low gas pressure or poor air supply and venting. Do not attempt to fix this problem yourself. Instead, contact a trained professional. 

Still Having Problems?

If you are still experiencing problems with your gas pool heater, contact a professional to diagnose and fix it. This should also be the case if you are uncomfortable in trying to deal with any complex electircal problems that may arise.