Rheem Pool Heater High Limit 2 Fault [5 Easy Solutions]

The Rheem pool heater high limit 2 fault means there is a failure measuring the temperature of the water leaving the heater, it has surpassed recommended temperature.

There are many reasons behind this issue. However, we will discuss the most common reasons and their solutions to this problem in this article. 

The reasons are scale build-up inside the heat exchanger, the Unitherm Governor is not regulating water flow, a faulty thermostat, a defective high limit switch, and a faulty control panel.

We are assure you that these reasons and solutions will help you to solve the pool heater HL2 error code problem of your Rheem pool heater very easily. Therefore, let’s get started.

5 Reasons Of Rheem Pool Heater High Limit 2 Fault [Easy Solutions]

The pool heater HL2 error code is one of the most common troubles of a Rheem pool heater. Here are reasons and solutions to HL code in detail.

1. Scale Build-Up Inside The Heat Exchanger

Scale build-up inside the heat exchanger causes very low flow via the heat exchanger. Therefore, causing very much heat transfer to the pool water because of the water moves very slowly through the heat exchanger.

The Rheem pool heater uses the Unitherm governor and an automatic bypass. These devices are controlled by the water temperature and pressure and will adjust the water flow to keep a further continuous volume of water and pressure moving via the heater.

In return, they provide the ability to compensate for flow difficulties and temperature swings. 

These two devices can also fail to open due to scale build-up. Scale build-up is the most common reason for the pool heater’s high limit 2 faults.


To solve it, you are required to remove the heat exchanger, Unitherm Governor, and auto bypass from the Rheem pool water header.

Then, soak them in vinegar and reinstall them to solve the problem. If the scale is very thick, a commercial descaler will be required. Also, you can simply replace the part if it is cost-efficient.

2. The Unitherm Governor Is Not Regulating Water Flow

If the Unitherm Governor of your Rheem pool heater is not regulating water flow, then the water is moving very slowly via the heater. As a result, it picks up a lot of heat. It will cause the HL2 fault issue on your Rheem pool heater.


To solve this, you need to inspect the Unitherm Governor. It can be inspected without disassembling much of the Rheem pool heater in only a couple of minutes.

Firstly, you need to turn off the pump. Then, with a shaft of a long screwdriver, unscrew the Unitherm Governor cap. You can find the cap just next to the outlet plumbing, it is a round cap with four notches. 

Now, inspect the Unitherm Governor’s condition. If it is pitted and rusted then it is likely your issue. The Unitherm Governor appears like a car thermostat but not exchangeable with one.

Finally, replace the Unitherm Governor by reversing steps to solve the problem. The cap will hold the Unitherm Governor to put back into place. Do not concern yourself very much about the gasket placement.

3. A Faulty Thermostat

A faulty thermostat won’t turn off at the set point to let the heater constantly run. But with it, you would see the pool temperature much warmer than required. However, it will cause the pool heater HL2 fault issue.


In this case, you need to repair or replace the thermostat to solve it.

4. A Defective High Limit Switch

A defective high-limit switch will also cause the high-limit 2 faults. As a result, your Rheem pool heater might not work.


In this case, you need to replace the high-limit switch to fix the switch’s difficulty.

5. A Faulty Control Panel

A faulty control panel will give faulty readings from an internal circuit board problem. As a result, it will cause the pool heater to high limit 2 error code and your Rheem pool heater might not work.


In this case, you need to change the control panel to solve the problem.


How To Solve Rheem Pool Heater High Limit 1 Fault Problem?

The Rheem pool heater high limit 1 fault problem means inadequate water flow inside the heater. It occurs because of an extreme build-up of scale in the heat exchanger and the spring-loaded bypass diverter of the heater. You need to remove both the heat exchanger and the bypass diverter from the heater. Then, clean them well and reinstall them to solve the pool heater HL1 fault issue.

What Does A High Limit Switch Do On A Pool Heater?

The high limit switch is very crucial in a pool heater. It is used to spot when your water temperature has surpassed a secure level of 135 degrees Fahrenheit and instantly opens the heat exchanger outlet when that occurs.

How Long Does A Pool Heater Last?

Relying on the weather of the place you live in and what temperature you aim to heat your pool, different pool heaters can generally last anywhere between 6 to 12 years. Some pool heaters can even last more than 20 years. Regular usage and maintenance of your pool heater are very important for a longer life expectancy.

Can Your Pool Heater Get Clogged?

A pool heater can get clogged, however, that is quite rare. The thing you need to remember is that the internal part of a pool heater is quite complicated, with a lot of small paths for water to pass through so that the most amount of heat gets moved. It will essentially make some back pressure when you attempt to run water via a garden hose and may get your pool heater clogged.

Does A Gas Pool Heater Have A Pilot Light?

Yes, a gas pool heater has a pilot light. But the pilot light can keep going out by wind or water before heating the pool entirely. You need to use a cover that will keep rain and snow out from the pool heater. In addition, you might require a pool heater wind stack to avert wind from getting to the pilot light. You need to also ensure that there is a sufficient gas supply in the pool heater.


A pool heater is an important part of our life, particularly for those people who want to swim in their pools because it heats the pool.

So, if your Rheem pool heater doesn’t work because of the Rheem pool heater high limit 2 fault problem, then you might be very worried. To remove your worries, we have come up with 5 reasons behind this error code and their solutions in this article.

We are hopeful that now after knowing these reasons and solutions of the pool heater HL2 fault code, you could solve this error code easily.

Still, if this problem doesn’t solve or any more help is required, then do let us know in the comment box. We will be very happy to help you ASAP.

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