Man fixing pool heater

Why Does My Pool Heater Keep Shutting Off?

In this article, you will learn about the possible reasons why your pool heater keeps shutting off, as well as some tips on how to troubleshoot and fix the issue. It can be frustrating when your pool heater keeps shutting off, especially during the colder months when you want to enjoy a warm and inviting pool. However, there are a few common issues that could be causing this problem, such as a dirty filter, a malfunctioning thermostat, or a gas supply issue. By understanding the possible causes and following some troubleshooting steps, you can hopefully get your pool heater back up and running in no time.

One possible reason why your pool heater keeps shutting off is a dirty filter. A clogged or dirty filter can restrict the flow of water, leading to overheating in the heater and causing it to shut off as a safety precaution. In this case, simply cleaning or replacing the filter should solve the problem. Another potential cause could be a malfunctioning thermostat. If the thermostat is not accurately reading the temperature of the water, it may erroneously shut off the heater. Adjusting the thermostat or replacing it, if necessary, can help keep your pool heater running smoothly. Lastly, check your gas supply. Low gas pressure or a gas leak can cause the heater to shut off. If you suspect a gas supply issue, it is crucial to contact a professional to avoid any potential safety hazards. Is this a question you find yourself asking often? If so, you’re not alone. Many pool owners experience the frustration of a pool heater repeatedly shutting off, leaving them with a cold pool and a headache. In this article, we will explore the common reasons for pool heater shutdowns and how to address them.

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Common Reasons for Pool Heater Shutdowns

Low Water Flow

One of the most common reasons for pool heater shutdowns is low water flow. This can be caused by a variety of issues, including a clogged or dirty filter, pump problems, or inadequate water levels. When the water flow is restricted, the heater may overheat, leading to a shutdown.

To address low water flow issues, start by checking and cleaning your filter. Remove any debris or dirt that may be blocking the flow of water. If your pump is not functioning properly, it may need to be repaired or replaced. Finally, ensure that your pool’s water level is sufficient for proper water flow through the heater.

Thermostat Issues

Another common culprit for pool heater shutdowns is thermostat issues. This can include an incorrect temperature setting or a faulty thermostat sensor. If the thermostat is set too low, the heater may shut off before reaching the desired temperature. On the other hand, a malfunctioning sensor may cause the heater to shut off prematurely or not turn on at all.

To address thermostat issues, start by checking the temperature setting on your heater. Ensure that it is set to the desired temperature and adjust as necessary. If the thermostat sensor is faulty, it may need to be replaced by a professional technician.

Pressure Switch Problems

Pressure switch problems can also lead to pool heater shutdowns. The pressure switch is responsible for detecting adequate water pressure, and if it fails to do so, the heater may shut off as a safety measure. This can be caused by a failure of the switch itself or a lack of sufficient water pressure in the pool system.

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To address pressure switch problems, start by ensuring that your pool’s water pressure is at the appropriate level. If it is too low, consult with a professional technician to determine the cause and find a solution. If the pressure switch is faulty, it may need to be replaced.

High Limit Switch Tripping

The high limit switch is designed to shut off the heater if it detects overheating. However, if the switch is malfunctioning or if there are blocked air vents preventing proper airflow, it may trip and shut off the heater unnecessarily.

To address high limit switch problems, start by checking for any blockages in the air vents of your heater. Remove any debris or obstructions that may be hindering proper airflow. If the problem persists, consult with a professional technician to diagnose and repair any issues with the high limit switch.

Ignition Failure

If your pool heater is not igniting properly, it may shut off shortly after starting up. This can be caused by gas valve issues or a dirty or faulty igniter. Without a proper ignition, the heater cannot function and will shut off as a safety measure.

To address ignition failure issues, start by checking the gas valve to ensure it is properly aligned and not blocked. If necessary, clean or replace the gas valve. Additionally, inspect the igniter for any buildup of dirt or debris. Clean or replace the igniter as needed.

Gas Supply Issues

Lastly, gas supply issues can also cause your pool heater to shut off. This can include problems with the propane or natural gas supply, as well as a misaligned or blocked gas valve. If the heater does not receive an adequate supply of gas, it will not be able to operate effectively.

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To address gas supply issues, start by checking your propane or natural gas supply to ensure it is functioning properly. If you suspect a problem with the gas valve, consult with a professional technician to diagnose and repair any issues.


In conclusion, experiencing pool heater shutdowns can be frustrating, but by identifying and addressing the specific cause, you can prevent future problems. Regular maintenance and troubleshooting are essential to ensure the proper functioning of your pool heater. Remember to check for low water flow, thermostat issues, pressure switch problems, high limit switch tripping, ignition failure, and gas supply issues. If the issue persists or if you are unsure about performing the troubleshooting yourself, it is recommended to consult a professional technician. By addressing these common reasons for pool heater shutdowns, you can enjoy a warm and inviting pool all season long.

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