How To Fix Hayward Pool Heater H5 Code/HS Code [Solved]

Hayward pool heater H5 code is one of the common error codes on Haywad pool heater. The H5 code identifies the water temperature sensing error report from inlet sensor.

The root reason behind H5 or HS error includes inadequate water flow, clogged water filter, and incorrect setting of the thermostat. Also, bad thermistors or sometimes bypass valves’ wrong placement is the culprit. 

Anyway, stay till the end to get the simple solution to fix the H5 error code on your Hayward pool hater.

How To Fix Hayward Pool Heater H5 Code [7 Easy Solutions]

Here, you will come to know all the responsive factors for displaying H5 code. Also, we will tell you a well-proven guide to fix the issue.

Note: Also read how to fix Hayward pool heater LO code

1. Inadequate Water Flow

Hayward heater HS code or H5 code is basically an error cord of the heater which indicates inadequate water flow from the pool heater. The water flowing rate of the heater differs from model to model. But naturally, the rate should be in the range of 25-30 GPM.

 In any case, if the water can’t be able to flow from the heater properly, the heater control system won’t allow the initiation of flame. And the heater starts showing an error as HS code telling you the water output temperature is getting too high.

So, in this period, you will need to adjust the water pressure by the pressure switch. With a proper adjustment, you can easily overcome the overheating issue of the heater.


  • First of all, locate the water pressure switch. You will find it on the left side and behind the front service panel.
  • Now, switch on the pump and heater.
  • This time, turn the adjustment knob of the pressure switch clockwise.
  • You will hear a clicking sound from the gas valve, and the heater will shut off. 
  • After that, turn the dialer 1/4 turn counter-clockwise.
  • The heater will immediately turn back on. 
  • Now, adjust the dialer clockwise to increase the pressure.
  • If needed, replace the pressure switch. 

2. Clogged Water Filter

When you notice a decrease in pressure coming out of your return jets, it signifies that the water filter gets blocked with debris.

A clogged water filter is another root reason behind the pool heater overheating issue. When the heater gets overheated, it shows HS as the indication of an error code. 

So, you will need to clean the filter to prevent flow restrictions from dirty filters. Also, it is a good recommendation to keep clean the filter once a month during swim season.

If it is oversized, it needs to be cleaned 3-4 times per year. Anyway, let’s know how to clean the pool heater filter:


  • Turn off your heater and leave it for some time to let it cool. 
  • Now, locate the filter of your pool heater model.
  • This time, remove the cover to gain access to the filter
  • After removing the filter cover, the filter will be easily inspected. But you may need to unscrew some attached screws if there are any.
  • Take out the filter carefully.
  • Place the filter on a hard surface and rinse it with the hose until it gets free of dirt and debris.
  • Also, clean the reservoir properly where the filter sits.
  • Finally, reassemble the complete unit the same as before. 

3. Incorrect Setting of the Thermostat

The thermostat is a very important part of any pool heater. It assists the heating system in keeping a steady temperature. For this, the heater gets heated continuously.

But to continue the thermostat operation fluently, it is a must to set the correct pool temperature

Excessive temperature settings will cause the heater overheating issue. Also, you will notice heater output temperature will get so high that it leads to the H5 error code. 


  • First, reset your heater thermostat.
  • Now, set the temperature point below 104 degrees.
  • Then, set the function “Ok”
  • Always keep the temperature under 104 degrees to allow the heater to heat the water at this temperature.

Note: Learn how to fix CE code on Hayward pool heater

4. Damaged Water Temperature Sensor

A bad temperature sensor is one of the major reasons for causing the heater overheating problems.

A thermal regulator, pressure sensor, or high-limit switch has a big role in the heater function. The function of a temperature sensor is mainly to control the heater temperature.

 It ensures that the temperature will not run so high that it damages the essential parts. But a defective sensor can’t able to control the temperature in any way and turn it off at inappropriate times.

However, this is the time to check out the sensor and replace it if needed.


  • First of all, locate the heater sensor from your heater model. Basically, it is located between the filter pump and the filter.
  • Inspect the sensor and check it sensibly.
  • If you find it corroded or defective, don’t be late to replace it.
  • But make sure the proper installment of the temperature sensor. 

5. Incorrect Position of Bypass Valves

Mainly a bypass valve is used in a pool heater to control the water circulation. It controls the direction of water flow as well.

Sometimes, incorrect installation of these valves leads to the water flow restrictions issue. 

Because of improper water flowing, the water temperature gets too high, and the heater unit becomes overheated.

So, to ensure a fluent heater operation and to get rid of any type of error code, it is needed to accurate adjustment of the valves.


  • Reset all the valves correctly into their position. 
  • Sometimes, opened valve creates a disturbance in the case of water flowing. So it will be better to close the valve for some while to allow the full water to flow through the heater.
  • Hopefully, the error code problem should be solved. 


Why is the Hayward pool heater not turning on?

Blockage in the water filter and clogged burner orifice are the root reasons behind the pool heater not turning on. The blocked filter restricts the normal water flow, and the heater fails to come on.

What is the IF code on the Hayward pool heater?

IF code on the Hayward pool heater mainly refers to the “Ignition Failure” or Fails to Ignite. Insufficient gas supply through the unit is highly responsible for displaying this code. 

How long does it take for the Hayward pool heater to work?

The heating fact depends on the size of the pool heater. Generally, a pool heater’s heat pump takes 24 to 72 hours at 20 degrees Fahrenheit to the pool. But if it is small in size, the heat pump needs up to 45 to 60 minutes. 

What does the HP code mean on the Hayward pool heater?

The “HP” code on a pool heater signifies “restricted water flow or low water flow.” In some cases, the code is displayed because of the high pool water temperature. The incorrect setting of the bypass valve is the main reason for the HP code.

Wrapping Words:

Hopefully, now you have understood the factors that are responsible for displaying the H5 code on the Hayward pool heater. You can easily figure out and fix the problem by following the above comprehensive guide. 

Still, if you have any questions regarding this guide, don’t be late to let us know through a comment. We are always ready to help you out.

About William

William is the founder of 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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