Troubleshooting a Hot Tub Heater
A hot tub is a great place to relax after a long day, but it can also be a bit challenging when the water temperature in your spa or hot tub is very low.

When it comes to hot tub temperatures, most people tend to use the temperature of 100 to 104 degrees Fahrenheit. This is the ideal temperature for most hot tubbers.

Keep reading our guide to learn how to repair a hot tub heater. First, you need to determine if you have a pressure problem, a power problem, or a part problem.



The water pressure in your spa should also be enough to operate. A proper pressure switch will help you keep your spa running smoothly.

When the water flow gets too high, the pressure switch is opened, which allows the heater to run. However, when the pressure drops below the minimum set point, the switch snaps shut, which prevents the heater from working.

When the water flow gets slow, the high limit switch can be tripped. This causes the heater to automatically raise the temperature of the water.

Most high limit switches can trip when they sense a water temperature of 140 degrees Fahrenheit.

If your circulation pump has a filter basket, make sure it is clean. It can also cause pressure issues if it's been more than 2 years old.

Aside from improperly draining or blocking suction inlets, improperly closing valves and pumps can also cause issues with flow.

If the pump is not moving water at all, then it is most likely running at low speed.

Rule out pressure problems first by making sure water is flowing as fast as it should be to operate the heater.



The next thing to check is the power to the heater. This is where the wires and connections come into play. If they are loose, the heater might overheat and cause a malfunction.

If you are not comfortable with testing voltage, then you can check the AC and/or multi-meter voltage on the heater's terminals. With the meter set to AC volts, and the pump running at high, you should see a voltage of about 220 volts.

If the heater element is not working, it's most likely due to the coating around the element. Also, make sure that the heater is in good condition.

If you still get no volts after testing the heater leads and terminals, make sure that the outlets are not tripped and the circuit breaker is engaged.

When the power goes off, the two heater terminals are tested for continuity. Touching the same lead at the same time helps minimize resistance fluctuations.

If the meter does not move, and the element shows steady resistance, then the element is probably good. However, if the meter shows short resistance, then the element could have a chip or cracks.

Rule out power problems by testing for voltage coming into your spa pack, and verifying that voltage is reaching your heating element.



The outer coating of a heater element can eventually crack or get damaged. This can cause it to fail even without obvious signs. Having a check for voltage and continuity can help determine the condition of your heater element.


Filter Cartridge

A clogged filter cartridge can cause your spa to malfunction, and it can lead to clogged crystals and oily residue.


Pressure Switch

When the pressure switch is blocked or the filter is clogged, it will prevent the heater from working. Also, it will keep the pump running at low speeds.

A pressure switch can be easily jump-out with a wire and alligator clips. Most pressure switches are designed to work with a variety of psi ratings.


High Limit Switch

The reset button located near the heater is typically used to prevent frequent tripping. High limit switches can also be prone to damage. They can be easily manipulated with a wire and alligator clips.



Many older models have a manual thermostat that is controlled with a small key. If the temperature gets too hot, or if it exceeds 104, the key should be turned off. Newer models use a circuit board to control the temperature.



This switch is used to confirm that the voltage is regular before the heater begins. It also allows the power to continue to operate.

Some contactors can be loud enough to trigger clicking sounds when connected to an element. However, they can also cause insect infestations.



Having a GFCI breaker is important to prevent the circuit from becoming sensitive. Also, having a GFCI outlet is also helpful to avoid having a tripped circuit interrupter. These are devices that sense when current is going to ground and can fail at any time.



The printed circuit board is the component that controls the functions of a spa. It is commonly used to prevent issues that can cause overheating and poor performance.

The complexity of a spa circuit board can be challenging to troubleshoot. Fortunately, most of the time, replacing a damaged pcb can be done in less than 10 years.

Rule out all possible problems by testing the components individually. When a spa heater does not operate, there is a component that is keeping it from working.


If you have any other questions about pool and spa products please do let us know - we are here to help!

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