Hot Tub Not Heating Properly? How to Diagnose & Fix It

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Are you having trouble getting your hot tub to heat up? Well, you’re not alone! Many hot tub owners run into issues with their heating systems at some point during a hot tub's lifespan.

This is unfortunately an especially common problem with Coleman (or similar) inflatable hot tubs, where the heaters tend to be one of the first parts to fail.

In this blog post, we’ll discuss what could be causing your hot tub not to heat up properly and how to diagnose and fix the problem. So read on to learn more so you can have your hot tub back up and running in no time.

Signs of a heating element problem

If your hot tub is not heating up properly, it is most likely due to a problem with the heating element. Your hot tub should be able to stay up to temperature as long as it has a properly fitting cover.

If it is not holding the desired temperature, or if the temperature in the tub is not consistent, it's likely that a heating element problem is the cause. There are a few signs that point towards a heating element problem:

  1. GFCI breaker is tripping: If the GFCI (Ground Fault Circuit Interrupter) breaker is constantly tripping, it could be due to a faulty heating element. Try to reset the breaker, but repeated tripping could indicate that the heating element is starting to burn out.
  2. Unusual noises: Strange noises coming from the hot tub, such as a humming, buzzing, popping or crackling noise, could also mean that the heating element is coming to the end of its life. It is best to switch off the hot tub in this case, as using it could be unsafe.

If you're not sure, it's best to get a professional to help you diagnose the issue.

Troubleshooting the potential causes

So you're fairly sure the issue is the heating element, but why did it fail?

Your heater is old

If your hot tub heater is old, it could simply be nearing the end of its natural lifespan. Check the warranty on the heater specifically. If it's out of warranty, chances are it could be time for a replacement.

Your heater has been corroded by low pH

Additionally, testing the water pH with a test strip may confirm if your heater has been corroded due to a low pH.

If you haven't been taking care to keep your pH in the 7.2-7.8 range for a period of time, and it's reading low now (especially below 7), then there's a strong chance this is the cause of the failure. Acidic water can cause heating elements to fail.

If either of these conditions seems to be the issue, it's likely that a replacement heater is the solution.

What to do while you wait for a replacement heater

So, you've ordered the part, but you have to wait for it to turn up—or for a repair technician to come and fit it.

First and foremost, it's very important to prevent your hot tub from freezing if this is a risk given current conditions. Without a heater, your hot tub will have no other way to prevent this.

A good temporary solution is to use a bucket heater to keep the spa water from dropping below freezing, ensuring a consistent temperature and preventing damage.

Despite the disappointment of waiting for a new heater, you can at least make sure the situation doesn't get worse in the mean time.

Steps to take after fixing the hot tub heater

Once you have successfully replaced your hot tub heater and it is working consistently once again, there are a few steps you should take to prevent this problem from reoccurring:

1. Keep the pH in the correct range: The correct pH in your hot tub should be between 7.2-7.8. This is important to ensure that your hot tub's heater and other components remain in optimal condition. Aim to check the pH every 1-3 days.
2. Check the electrical connections regularly: Make sure that all electrical connections to the heater, pump and other components are securely in place and that there are no loose wires causing issues. You can perform this check every year or so, or get a technician to come and do it for you.
3. Monitor the temperature: Check the temperature regularly to make sure that it's staying constant, and not showing signs of dropping again when you don't expect it to. This is especially important if you don't use the spa often, so you can identify any problems with your new heater while it's still under warranty.

By following these steps and regularly checking the function of your hot tub's components, you can help your hot tub to stay running smoothly.

Closing thoughts

Troubleshooting a hot tub that's not heating can be a DIY task you can manage with a few helpful tips and some basic tools.

If the issue persists after trying the troubleshooting steps suggested in this post, or if you're not comfortable diagnosing yourself, it might be a good idea to call a professional hot tub technician to check it out. They’ll be able to diagnose and repair the issue quickly and safely—so you can get back to enjoying your hot tub.

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