Common Hot Tub Heater Problems You Need To Know About

The heater is probably the most important component of a hot tub. Without it, you wouldn’t be able to relax your joints and muscles in hot water.

If the hot tub is not heating water like before, you may have to replace or fix it. In these situations, it is best you contact the manufacturer first if you do not have prior experience with repairing hot tub heaters.

Do I Need A Hot Tub Heater Replacement?

Since most heaters are enclosed, you will need to look for indicators and cannot simply rely on visuals for replacement. If the GFCI receptacle of your hot tub isn’t the same anymore, you may be in need of a replacement.

GFCI Receptacle Next To Hot Tub

When hot tub heaters expire, it causes the GFCI to trip. The hot tub not being able to heat up properly might also be an indication that there is something wrong with the temperature sensor. Contact a professional if you think there is something wrong with the wiring.

Common Hot Tub Heater Problems

Here is a guide to common hot tub heater problems:

Low Water Flow

Have you been dealing with low water flow? The hot tub heater relies on sufficient flow to work properly. The heater features a pressure switch located in the heating chamber. If the water flow is not sufficient enough, the electric circuit powering the heater element shuts down until proper water flow is established again.

Rest assured, if you are experiencing problems with the water flow, you need not worry about repairing the heater parts.

This is because low flow is commonly associated with a dirty spa filter. If the spa heater is not operating, simply remove the cartridge and clean the inside of the filter. Insert the newly cleaned filter and inspect if there are still any problems regarding water flow.

Severe water flow problems may be caused by clogged pipes, broken valves, damaged pump impellers or clogged spa jets. These problems will be noticeable if there is significantly reduced water flow.


The thermostat is the dial you rotate to increase the heat. Most advanced hot tubs feature a solid state thermostat that is connected to a circuit board. If your thermostat has a knob instead of a lighted red arrow, inspect it to see whether there is an internal fault with the system or if the sensor bulb has been corroded.

Hot Tub Thermostat

High Limit

The high limit is a switch that is similar to the pressure switch mentioned above. The main purpose of a high limit switch is to prevent a run-away spa heater (one that will not shut off). It has an upper limit (present maximum heat) at which the switch will open and will carry power to the spa heater element.

Other common problems with spa heaters include:

  • Corrosion
  • Reduced heat
  • ​No heat
  • ​Dry Fire
  • GFCI Circuit Tripping/ Power Problems

There are several reasons that may have caused the hot tub heater to fail. The common problem is typically dry fire. This is mainly caused when the spa water fails to reach the spa heater or when the spa heater is switched on with little or no water in the heater unit. This causes the element inside the heater to rise above its safety level, destroying the inside of the machine.

These signs are usually hard to ignore and are often quite visible. If the heater is cracked or bumpy, you will need to have it replaced.

Additionally, reduced heat and no heat is also a common problem. No heat usually indicates there is something wrong with the heating coil, assuming all the other components have been plugged in properly and the thermostat high limit switches are working fine.

Heater Next To Hot Tub Outside

On the other hand, reduced heat is commonly associated with reduced water flow. Poor chemical balance, scale-build up on the heater element or obstructions restricting water flow can also contribute to poor water flow.

Spa Heater Problem Causes

Are you unable to figure out why the hot tub heater isn’t working properly? Here are a few common causes that you should check for first. This includes:

  • Loose Wires – Ensure the connections are tight and not oxidized. If you have a rat problem at home, check to see whether the wires have been chewed by rodents. Damaged wires will prevent the heater from working its best.
  • Spa Cover – Broken, ill fitting, warped spa covers may cause heat to escape from the system.
  • ​Spa Pack Door Interlock – Ensure the spa pack door is secured closed. Some spas only work if the equipment door is fully inserted and shut completely.
  • GFCI Tripped – Inspect the electrical outlet on the spa pack, if the button is popped out, push it back into place again.

Spa Heater Element Replacement Poses a Safety Risk

Do not attempt to repair the heater element by yourself as it may possess a serious health threat to you and your children if there are nearby. It is advised you have the entire heater repaired and replaced as a faulty wire or improper installation can result in serious injury or even death.

Keep in mind that the cost associated with a spa control system is minimal compared to the damage it can cause.

Covered Hot Tub Outside


Hopefully, this article has provided you enough information about the common problems associated with hot tub heaters. Since the heater is designed to be hidden inside the machine, it is important to have it checked or inspected after every few months.

Instead of trying to repair the heater components by yourself, we recommend you contact the help of a professional. There are many websites and video tutorials that will help you locate the hot tub heater and identify the problems associated with it. Good luck!