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Backyard Blogging.

Troubleshoot Your Hot Tub Heater

There is nothing worse than stepping into a hot tub that isn’t hot. Whether your water is room temperature or just lukewarm, it just isn’t the same experience when you compare it to the nice hot soak in a tub in proper working order.

In this article, we’re going to learn how to troubleshoot your hot tub heater.While you may think that if your hot tub isn’t heating properly it is probably due to the heater, there are actually many different possible causes that may not even involve the heating element at all.

Of course, sometimes it is the heating element that is the culprit, and you have to change it to return your hot tub to normal heating order.

Before we get to that, let’s examine what makes up the heater in your hot tub.

Heating Element Assembly

In a typical hot tub, the heating element coil is contained within a heater assembly housing. This housing exchanges the heat produced by the heating element to the water as it flows through the tube. Many heating assemblies also use sensors such as a thermostat and a high limit switch, to prevent the water from becoming too hot.

Most Common Heat Problems

While you could experience many different issues with the heater on your spa, let’s discuss some of the most common heat problems you will run into over the course of your hot tub ownership.

Hot Tub Not Staying Hot

If your hot tub heats up with no problem but then seems to just fizzle out and begins to cool just like you were taking a typical bath, then there are a few things you should check yourself before calling in a professional.

First, check your filters to make sure there are no clogs. If you find debris, give it a good cleaning. From there, you should check the thermostat and any heat sensors on your tub. These could have gone bad and need replacing so they monitor and maintain the proper temperature in your hot tub.

You should also check to make sure your water is circulating properly in your hot tub. If there is something clogging up the plumbing preventing the water from circulating properly it will not heat properly and therefore begin to cool while you use it.

Hot Tub Not Heating or There is No Heat

If you head out to your spa and realize that the water is cooler than it should be or you find that there is no heat at all, then there are a few things you should check. First, check to make sure your filter is clear and in good condition. If it is, you could have a bad heating element.

When your heating element goes bad, you will have to shut down your hot tub for maintenance so you can replace it.

Fluctuating Temperatures

Personally, this is one of my least favorite problems, not because it is hard to repair, but because it fools you into thinking nothing is wrong. You turn on your hot tub and slide into the warm water and then five minutes later you are shivering because the temperature has cooled off even though you haven’t done anything. Then, five minutes after that it heats up so hot you are afraid your tub might force you to take a trip to the burn unit at your local hospital.

Fluctuating temperatures are most often caused by a temperature sensor that has started to go. If your sensor is in good order then you could have a bad thermostat or even a clogged filter.

Replacing the Heating Element

Sometimes, your spa’s heating element will be faulty and responsible for all your heating problems. This happens more frequently than you may think, after all, your heating element works much like a regular light bulb. Luckily, replacement is a pretty straightforward repair.

Before you begin, disconnect all power to your hot tub. Locate the heating element assembly inside your hot tub. Using two wrenches, remove the old assembly by disconnecting the electrical wires and replacing it with the new one. All in all this repair shouldn’t take you too long to accomplish even if you are doing it yourself.

Prevention Is Key

There are things you can do to prevent your heating element from failing on your hot tub.

  1. Balance your water. Balanced water will prevent corrosion inside your hot tub and extend the life of your heater.
  2. Clean your filters regularly. Clogged filters can prevent water from flowing to the heating element properly and cause the heater to essentially burn out. Check your filter regularly and clean or replace it whenever necessary.
  3. Avoid excessive air in your system. Before you begin using your hot tub after regular maintenance, make sure you flush all the air out of the system. Too much air can lead to premature failure on your heating assembly.


There is nothing worse than sliding into a hot tub that isn’t properly heated. Trust me, I have been there. You don’t expect pool temperatures when you uncover your hot tub, so needless to say it can be quite the surprise.

Dealing with heating issues is something every hot tub owner will have to deal with at one time or another. If you find yourself in that situation, take a step back and analyze the situation to find out what your hot tub is doing and then take the proper steps to repair it. If you must, call a professional, but many of these repairs and troubleshooting steps can be done yourself. No matter what, don’t just take cold hot tub water lying down. Take a few minutes to look into it so you can get back to that warm soak you were expecting before you noticed the problem.

Need help? Give Ultra Modern a call, contact us or stop by one of our three locations, and our expert service staff can help you!

Reprinted with permission from Matt at Swim University.