Pool Heater Won’t Turn Off [7 Easy Solutions]

Pool heater won’t turn off mainly due to the gas valve malfunction, a defective thermostat, a damaged primary controller, and blocked air vents.

The other reasons for this problem are the lousy control board, clogged air filter, and damaged fan motor.

pool heater won't turn off

Replace your pool heater’s malfunctioning gas valve, thermostat, corroded primary controller, damaged fan motor, and bad control board. Also, remove the air vent’s blockage and clean the clogged air filter. 

Go through the detailed explanation below, and you will surely learn how to turn off Hayward pool heater.

Pool Heater Won’t Turn Off [7 Easy Solutions]

The pool heater won’t shut off is an alarming situation. Running the pool heater constantly causes an extreme rise in water temperatures, and it could lead to greater danger.

In the following section, we explained the root of this issue and their easy solutions. Let’s start:

1. Defective Gas Valve

A lousy gas valve is one of the main reasons why your Pentair pool heater won’t turn off. The bad gas valve fails to maintain the heater’s adequate gas pressure.

As a result, the heater won’t shut off and run continuously. The factors that lead to this are:

  • Incorrect wiring between the thermostat and gas valve
  • Worn-out gas valve
  • Closed gas valve
  • The pool heater’s gas valve is set to the “Off” position
  • Thermocouple to the gas valve’s rusty or lose connection


The pool heater’s heating system keeps turning on due to the gas valve’s malfunction. If your pool heater doesn’t shut off, first check the heater’s gas valve. To get rid of these above troubles, follow the easy ways below:

  • Check and remove the incorrect wiring running between the thermostat and the gas valve. And install a new wire set properly between these two.
  • Replace the worn-out, damaged, or defective gas valve
  • Ensure your pool heater’s gas valve is open
  • Make sure your heater’s valve is set to the “On” position
  • Ensure the thermocouple to the gas valve’s proper connection

2. Faulty Thermostat

Due to the thermostat malfunction, your Hayward pool heater won’t turn off and continue to run. The heater keeps running as long as it doesn’t reach the pre-set temperature.

Due to the defective thermostat, the water remains so cold. And the thermostat’s temperature setting fails to go below the pool’s current water temperature. The causes of it are: 

  • Thermostat’s faulty wiring
  • Broken switch or relay
  • Damaged or corroded heating sensor
  • The thermostat is set too low
  • Hooked up thermostat Select Switch
  • Too old thermostat


The thermostat controls your pool heater’s entire running system. The heater gets a signal from the lousy thermostat to run continuously. Thus, check the thermostat and immediately replace your faulty thermostat if it is the culprit. 

Follow the resolving ways below, and you will learn how to turn off Hayward pool heater:

  • Check the thermostat’s wiring and replace the bad wiring
  • Replace the broken relay or switch, damaged heating sensor, and too old thermostats
  • Make sure the setting of the thermostat is not too low
  • Ensure the thermostat’s Select Switch is not hooked up

3. Damaged Primary Controller

The pool heater’s primary controller responds to its thermostat. Also, the primary controller controls the heater’s running cycle (On and Off).

Your pool heater will fail to turn off if its primary controller becomes damaged. The factors that cause it are:

  • Short cycle
  • Faulty circuit breaker
  • Dirty filters
  • Faulty primary control relay


If the bad primary controller is the root of this trouble, fix it in the following ways:

  • Ensure stable electricity supply to your pool heater
  • Replace the malfunctioning circuit breaker and bad primary control relay
  • Clean the dirty filters

4. Blocked Air Vents

The pool heater requires an adequate air vent to ensure its proper operation. Blocked air vents reduce the airflow. As a result, your pool heater runs longer. The concerning causes of it are:

  • Dirt, debris, or grime builds up in the heater’s air vent
  • Damaged air vent
  • Leaking vents


To solve the above troubles, you need to know how to turn off the pool heater. To shut off the heater, you need to check your heater’s air vents and make sure there is no blockage. Properly clean clogged air vents and do the following to solve this trouble.

  • Remove your pool heater air vent clog or dirt build-up
  • Replace the damaged and leaking air vents

5. Bad Control Board

If your pool heater’s on/off switch fails to shut down and your pool heater won’t shut off, the faulty control board can cause this suffering. The control board goes bad for the following reasons:

  • Broken internal parts
  • Damaged IC
  • The control board itself is defective or has stopped working
  • Faulty wiring or cable connection
  • Electrical connection malfunction or bad power supply
  • Blown fuse
  • The old-aged control board
  • Exposure to excessive dust, moisture, or heat


The simple ways of solving the above troubles are: 

  • Replace the control board’s broken internal parts, damaged IC, faulty or old aged control board, blown fuse, and damaged wiring 
  • Check the power supply and replace the faulty circuit breaker 
  • Ensure the control board is not facing excessive moisture, dust, or heat 

6. Clogged Air Filter

Blockage in air filters creates problems in the HVAC system. The clogged filter restricts the smooth water flow. As a result, your pool heater fails to reach the set or ideal temperature, and it keeps running longer. 

The main accountable factor for it is the dirt, dust, or debris build-up in the air filter. The clogged filter reduces airflow, and the pool heater can’t function properly.


Check your pool heater’s air filter. If it becomes clogged and dirt gets on it, you should properly clean the clogged filter. However, you should replace the air filter if its performance decreases due to its dirt coverage.

7. Damaged Fan Motor

The pool heater fan motor heats your pool’s water by drawing ambient air. The fan motor provides a signal to your pool heater’s running cycle, i.e., when to turn off and on the heater. 

So if the fan motor doesn’t work, your pool heater will also not work, and it will run continuously. The causes of it are:

  • Faulty wiring and improper connection
  • The fan motor itself is defective
  • Clogged fan motor or build-up of outside debris in it
  • Burned out capacitor
  • Broken heat pump fan motor
  • Broken or slipping fan blade


The fan motor malfunction causes continuous running of the heating system, and the pool heater fails to shut off. The easy solving ways to these troubles are:

  • Check your pool heater’s fan motor wiring and replace the damaged wiring
  • Replace the defective or broken fan motor, burned-out capacitor, and broken or slipping fan blade
  • Clean and remove the fan motor’s blockage


Will the pool heater turn off when the pump stops?

Yes! Your pool heater will also turn off after shutting off the pump. The pool’s pressure switch keeps the heater running when it has sufficient pressure. If the heater runs after shutting off the pump, it could be hooked into the timer clock.

What does the IF code mean on a Hayward Pool heater?

IF code on your Hayward pool heater means Ignition Failure. Insufficient gas supply, gas valve malfunction, and dirty filters are the most common reasons for this trouble.

How do I test my pool heater thermostat?

Check your pool heater thermostat’s temperature setting and ensure that it is higher than the pool water. Your pool heater turns on due to increasing temperature and it indicates the thermostat’s good condition. Also, you can use the multimeter to test the thermostat’s power-receiving force.

What does a high-limit switch do on a pool heater?

Your pool heater’s high limit switch detects whether the pool’s water temperature is more than the safe level or not. If the pool’s water temperature exceeds 135 degrees Fahrenheit, it opens the heat exchanger immediately.


So, now you know all the major reasons why your pool heater won’t turn off. If any of the above factors cause an issue in your pool heater, expectantly, you will now solve it by yourself. 

If still, after trying out all our solutions mentioned above, your heater won’t shut off, don’t hesitate to comment. Comment on your trouble, and we’ll help you with the solution.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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