Raypak High Limit 1 Fault & 2 Fault [Solved]

Excessive water temperature in tube bundle, blocked tube, low water flow, defective Unitherm Governor, and bypass assembly malfunction are responsible for the Raypak high limit 1 fault & 2 fault. 

raypak high limit 1 fault & 2 fault

Also, the other additional factors such as the dirty switch connection, bad switch are responsible for it.

And the calcification on the heat exchanger or faulty wiring from the switch back to the heater’s board can cause the opening of high limit 1 & 2 sensors on your Raypak heater.

This HL fault codes will disappear from your Raypak pool heater if you can ensure the tube bundle’s adequate water temperature.

Also, you need to remove the tube’s blockage, ensure adequate water flow, and replace the lousy Unitherm Governor and subpar bypass assembly. 

However, go through all the detailed causes and solutions below. And you will surely learn how to fix these high limit 1 and 2 fault error codes on your Raypak pool heater.

High Limit 1 Fault VS High Limit 2 Fault

You will find two high-limit switches available in your Raypak pool heater that prevents its overheating. When your Raypak heater’s high limit exceeds 135 degrees Fahrenheit and the high limit 1 switch becomes open, the display shows a high limit 1 fault.

On the other hand, when your Raypak heater’s high limit 2 switch becomes open due to exceeding the 135 F temperature, the heater’s digital display shows the high limit 2 fault.

A high limit 1 fault code on your Raypak heater means the high limit 1 sensor is open. And the high limit 2 code on your Raypak heater indicates the high limit 2 sensor is open.

When both the switch and sensors exceed the 135-degree temperature, it shows the fault code on your heater.

To know which high-limit switch is bad, you can check the high-limit sensors. When you set your Raypak heater to call for the heat, bridge the 2 high limit sensor with the spade connectors using a wire’s small piece of wire on the heater header.

Start with checking one sensor and then check the other. You will get to know which high limit sensor is bad if your heater fires.

Raypak High Limit 1 Fault/2 Fault [5+ Easy Solutions]

High limit 1 or 2 fault on your Raypak heater means the high limit has exceeded or more than 135 degrees Fahrenheit. The major causes and solutions of it are:

1. Tube Bundle’s Excessive Water Temperature

Failed heat exchanger tube is responsible for the Pool heater high limit 1 or 2 fault issues. Tube bundle goes through the possible excessive water temperature for the following reasons:

  • Tube erosion and corrosion, Water hammer or steam
  • High-temperature differentials or thermal fatigue
  • External or internal vibration or resonance imposes powerful forces on the tube’s bundle and Mechanical failure


The tube bundle’s excessive water temperature causes the heater’s overheating and the heater displays HL1/HL2 error codes. If the water temperature rises, turn off your heater and allow some time to cool the unit.

Once the heater becomes cool, automatically, the high limit will reset. The other solutions are:

  • Check your heater’s heat exchanger tube and replace the corroded tube
  • Make sure the heater is not facing water hammer or steam
  • Check the high-temperature differentials and the heater’s mechanical failure
  • Ensure the tube bundle is not going through the external or internal vibration

2. Blocked Tube

Another cause of displaying this High Limit 1 or 2 error code on your Raypak pool heater is the blockages in a tube. So, the possible reasons for it are:

  • Dirty tubes or dirt, debris, or foreign objects build up in it
  • Lack of cleaning or maintaining the tube for an extended period
  • Closed tube
  • Leaking or damaged tube


To find out which tube is blocked, you need to run your Raypak pool pump and check the tube individually. By shutting off the other lines, check each line by itself. The other solutions are:

  • Check and adequately clean the tubes and remove the tube’s dirt or debris build-up
  • Follow a maintenance routine and clean the tube at a regular intervals
  • Make sure the tubes are open
  • Replace the physically damaged, worn out, or leaked tube

3. Low Water Flow

After turning on your Raypak pool heater, its digital display may say the High Limit one or two sensors is open due to the low water flow. The accountable factors for it are:

  • Clogged strainer basket, Low water level, Blocked filter or impeller
  • Suction leak at pump and diverter valve, Faulty plumbing fitting
  • The clogged pipe that is going to the pump, Opened too many water features and Too small pump


Check your Raypak pool heater’s water flow and make sure whether the low water flow is causing this trouble or not. If so, follow the solutions below to fix your heater’s inadequate water flow hitch:

  • Remove the strainer basket’s blockage by cleaning dirt and debris from it
  • Ensure the high water level, Properly clean the filter or impeller’s blockage
  • Replace the leaking diverter valve, pump, defective plumbing fitting, and too-small pump
  • Check the pipe that is going to the pump and make sure there is no blockage in it

4. Faulty Unitherm Governor

The defective Unitherm Governor creates a groaning noise during heating, and your Raypak pool heater’s digital displays say the HL1/HL2 sensors are open.

When the high limit 1 or 2 is open, the heater doesn’t heat for a few minutes and then resumes its activity. The causes of its malfunction are:

  • Physically damaged, worn-out, or broken Unitherm Governor
  • Bypassing too much water for testing the Unitherm Governor’s operation
  • Pitted or rusted Governor


When the Unitherm Governor fails to regulate the heater’s water flow, the water moves slowly through the Raypak heater and causes this HL1/HL2 error code. The ways to fix these issues are:

  • Replace the physically damaged, broken, worn-out Unitherm Governor
  • Don’t put excessive water pressure to test its operation
  • Also, check and replace the rusted or pitted Unitherm Governor

5. Bypass Assembly Malfunction

The bypass assembly installation prevents water freezing by allowing the water circulation around the Raypak pool water circuit.

Any issues with the heater’s bypass assembly cause displaying this HL error code. A faulty spring or bypass can cause this fault.


Check your Raypak pool heater’s bypass assembly and replace the bypass and spring if required. Make sure your heater’s bypass assembly kit is functioning perfectly.

6. Malfunctioning High Limit Sensor

The faulty high limit sensors fail to function properly, and the switches get open. As a result, your Raypak heater digital display shows high limit 1 & 2 faults. The causes of it are: 

  • Air problem or air trapped in the system 
  • A damaged or broken high limit sensor 
  • HL sensor requires a reset 
  • Calcium buildup 
  • Improperly calibrated thermostat 


If you experience the HL 1 & 2 error code on your Raypak heater first, you should check the high limit sensors. Make sure the sensors are working perfectly and do the following to solve the above troubles: 

  • Ensure that there is no air problem in your Raypak heater and air is not trapped in the system 
  • Replace the broken or damaged HL sensor 
  • Reset your heater’s high limit sensor 
  • Remove the calcium buildup 
  • Make sure the thermostat is properly calibrated 

How To Clear High Limit 1 & 2 Fault By Resetting HL

To clear your Raypak pool heater’s high limit 1& 2 faults, follow the steps below:

  • Holding the heater’s control cover, remove the 4 screws. Swing the control panel down to ensure the visibility of the board’s backside
  • Access the heater’s program screen and press its Mode Button to reset the limit. 
  • Press the “Mode” twice. Press once to off and then press again to back on
  • Press the button as long as the heater’s digital display doesn’t show the message “Clear Faults.”
  • Until the message “Faults Cleared” appears on display, press the Up and Down buttons and hold it for 5-7 seconds to reset the limit 
  • This operation will clear your Raypak heater’s all the stored faults, and the Faulty History file will reset to 0.

2 More Raypak Heater Faulty Codes

In addition to High Limit fault codes, your Raypak heater’s digital display may show other error codes also. Some of these are:

i) Raypak Heater Fault Code PRS

The PRS error code on your Raypak pool heater means low water pressure. The causes of it are:

  • Inappropriate water levels at skimmer face
  • The pump is not running
  • Inadequate filter pressure  
  • Improper installation of heater or heater’s unadjusted location


To fix the above troubles, do the following:

  • Check the skimmer’s face water level and ensure the water level is in the middle of the skimmer’s face
  • Make sure the pump is running, Check the heater’s filter pressure and heater location and adjust the pressure switch if necessary

ii) Raypak Heater Fault Code IGN

The IGN error code stands for Raypak heater ignition failure. The accountable factors for it are:

  • After 3 attempts, the unit fails to hold the flame and goes into the hard lockout
  • The pilot has proved and heater’s main valve is not powered
  • Lack of enough gas pressure


The easy fixing ways of the above troubles are:

  • Clear the hard lockout by interrupting the power supply
  • Make sure the main valve of the unit has been powered
  • Check the gas line air and make sure the gas pressure was enough


Why does my Raypak Pool heater keep shutting off?

Your Raypak pool heater keeps turning off because the heater display’s water flow light doesn’t lit up, there is inappropriate water pressure, faulty filter pump, dirty or blocked filter, etc.

Why is my pool heater not heating my pool?

Your pool heater is failing to heat up due to a filthy pool filter, obstructed airflow, faulty parts or defective pump basket, and low water flow-restricting the proper water flow of your pool heater.

How long does a Raypak pool heater last?

The average life expectancy of a Raypak pool heater is 6-12 years. But if you maintain your heater, clean it properly, and balance the water chemistry, your Raypak pool heater can last longer.


So, the major causes of Raypak high limit 1 fault or 2 fault are now apparent to you. If your Raypak pool heater’s digital display suddenly shows this error code, you can now fix it by yourself by simply following our guide mentioned above. If you fail to solve it, don’t hesitate to comment. We will soon help you.

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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