Why Does My Pool Heater Shuts Off Before Reaching Temp?

The pool heater shuts off before reaching temp is a common issue people complain of.

It doesn’t only hamper the pool heating system but also the water filtration. This inadequate heating can happen for various reasons. Sometimes it can be just a wrong timer set, manufacturing faults, malfunctioning heating parts, faulty pressure sensor and many more things.

How you should troubleshoot the filter will depend upon what is the exact issue.

Give a quick check over the pool heater if such a sudden shut down issue appears. You need to fix such problems to avoid bigger damages to the heater.

What is the ideal temp for a pool heater?

The average pool heater temperature should be around 25 to 28 degrees Celsius/ 78 to 83 degrees Fahrenheit.

However, this temp will vary depending on various factors.

It can be the environment, humidity level, swimmers requirement, outdoor temperature, etc. Your swimming pool size will also play a vital role here. What is the pool size and what is your pool heater capability will control a lot.

You should set the pool heater BTU regarding all these factors. BTU is the measured amount that indicates your pool heater temperature control capability. The BTU ( British thermal unit) should be around 75,000 BTU to 450,000 BTU.

You can see the temperature level and track the constant report over the thermostat. You can use a regular thermometer to measure the pool temperature as well.

Why Does My Pool Heater Shuts Off Before Reaching Temp?

You should already know, several things can make the pool heater shut off before reaching the set temperature.

However, give a quick check over these five most common things that can cause such interruption in your pool heating system:

Dirty Filter

A dirty filter in the pool heater is the most common thing that causes an interrupted pool heating system.

If you don’t clean the filter properly, it will create clogs in the heater’s sensitive parts. As a result, they will create clogs.

If the heart can not flow air properly, it can overheat the entire system. And overheating makes the pool heater shut off automatically.

Fx it soon, else your heater can die in the long run. 

Imbalanced Water Chemistry

This is one of the most vital facts that can interrupt your pool heating system.

If the pool water chemistry is not blanched properly, your heating equipment will fail.

That is why you should always be concerned about what and how many chemicals you’re mixing with your pool water.

Faulty switch/ sensor/ regulator

If your pool heater switch, sensor and regulator get damaged/ faulty, it can hamper the heating system.

Suppose you’re experiencing a sudden shut-off problem in your pool heater, test all these related switches/ thermal regulators and pressure sensors. 

If you notice any damages in these parts, replace them soon. 

Wrong size

Your pool size and heater size should be balanced. That is why you better do good research before getting any pool heater.

It’s better if you take expert’s suggestions for better help. The wrong size of heater will fail to supply efficient and adequate heating in your pool water.

As a result, it can cause sudden on/ off issues. 

Leakage in the refrigerant

The Refrigerator controls a lot with the pool heater.

If the weather is cold, your pool heater takes the heat from outside and supplies it into the pool water to make it higher in temperature.

But sometimes, your refrigerant can get damaged and cause leakages. Such leakages will ruin the pool heating system. 

How to Fix a Pool Heater that keeps On and Off?

If your heater is also creating such an issue, you must give a quick check over them. If you’ve found any damaged parts, hire a professional immediately.

Any defective cord/ switch/ sensor will certainly create major damages. It can even create electric shocks and accidents. You better replace any faulty parts soon. 

There are some other tips to fix a faulty pool heater. Follow here:

  • Clean the filter regularly. Poor Maintenance over the pool, heater and filtration system will make clogs over the machine. You must take proper care of the pool heater-sensitive parts.
  • You also have to check your pool heater valve. Make sure the valve is supplying adequate fuel for your pool heater. 
  • Make sure your pool heater has got no corrosion over the terminals. If such things happen, you might need to replace the part.
  • Make sure your pool heater transform is working efficiently. 
  • Check on the pool heating transformer wisely. It should always be 20 to 28 volts. Anything lower than that will supply lower heat in the pool. And it can shut off before reaching the ideal temperature.
  • Use your heater wisely. Wrong use of the heater can cause such issues. You need to balance the temperature by using the heater effectively. As if the heater is on overnight, keep the heater at a lower temperature in the morning. It helps to keep a balance both with the pool heater and water temperature.

Frequently Asked Questions

What to do if my pool heater won’t turn on?

If your pool heater doesn’t turn on, you might be having an issue with the heater motor. Here the best solution can be replacing the motor with a new one. However, you can consider giving it a full check before reaching any conclusion.

What to do if your pool heater is oversized?

Well, if your pool heater size is bigger than the pool size, you can still use it adequately. Just set a lower temperature to balance the heating system. It’s better if you go for an oversized pool heater rather than undersized ones. 


The pool heater shuts off before reaching temp can happen with any pool heater. If your pool heater is old enough, it would be the damaged parts. A faulty pool heating system won’t keep balance in the pool water temperature. You better find out why your one manages these issues. Fix the faulty pool heater and enjoy quality time in the pool.

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