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Why is My Hot Tub Not Heating Up? (Common Issues with Solution)

Hot tubs are vastly used all over the United States. The sole purpose of using a Jacuzzi is to experience that awesome warm soaking experience, especially in colder weather. So, when you feel the water of the tub isn’t warm like it used to, it is pretty safe to say that some technical problems have occurred. Now, what are the reasons behind this phenomenon?

The water in the hot tub might not heat up for several reasons. For instance, if there is a problem regarding the flow of water, you will face heating issues. This is the most common problem that people face. Some of the other reasons include malfunctioned heating elements, malfunctioned control board, poor insulation, using air blower, and so on.

One of the most common questions that I get asked is “Why is my hot tub not heating up”. So, here, I will extensively explain it. For a better understanding of this topic, it would be wise to read through the whole article.

Reasons Behind Hot Tub Not Heating Up

I know how frustrating it can be when this problem occurs; especially in the winter season. But don’t worry, it is highly unlikely that the issue is unsolvable, and with my guide, you can fix it yourself. Now, I will talk about some of the most common reasons behind this problem.

Water Flow Issues

One of the most common issues that may interrupt the heating problem of your tub is the irregular water flow. Now, if you notice the water is warming up very slowly, or the heating process is abnormally stopping, then you can be pretty sure that the water flow is slower than necessary.

In most of the hot tubs, there is an indicator that displays the flow speed of the water. It is usually placed somewhere at the top side of the Jacuzzi. Now, if you see something like “LF” or “FLO” in the indicator display, you can be 100 percent sure that the slow water flow is causing the issue.

The heater of the hot tub is an electrical device and water is a great source of electricity. Now, if the heating element of the Jacuzzi doesn’t get enough water, there is a built-in automated process that disconnects the heater with liquid. Otherwise, the water might get so hot that your skin will start to burn.

Malfunctioned Heater

Now, if you don’t detect any problem with the flow of the water, then the problem could be with the heater of the Jacuzzi. If the hot tub is properly plugged with a power source, but still the water is not warming up, that means the heating element of the tub has become faulty.

Now, checking the status of the heating element is a very complicated task, and without proper basic knowledge, cannot be performed. That’s why I will highly suggest you get professional help to fix your Jacuzzi. If you have a multimeter, then you can check whether electricity is passing through as the problem might be associated with the power source as well.

Malfunctioned Control Board

If the problem is not associated with the water flow or the heating elements of the Jacuzzi, then there is a very high chance that the hot tub's control board is malfunctioning. For those who don’t know, the control board is like a hub of all the working components of the Jacuzzi. Both the heater and pump are run by the control board.

Now, there are two possible issues regarding the control board, either the printed circuit board (PCB) is not responding, or, in worse cases, the entire board is malfunctioning. If the whole board is unresponsive, then the only thing that you can do is replace it with a new one. Unfortunately, control boards can be very expensive and the price can be as high as a thousand US dollars.

Now, if your hot tub was imported from another country where the power outputs are of completely different values, then even determining the source of the issue might be very difficult, let alone fixing it. Moreover, control boards are very power sensitive, and the wrong type of voltage input will fry them completely. So, buying hot tubs from local stores is recommended.

Poor Insulation

We all know that heat can very easily transmit from one particle to another. Now, when it comes to Jacuzzi, the water will lose most of its heat through the surface. In fact, almost sixty percent of the heat will very quickly transmit. That is why having perfect insulation is very important to trap all the warmth inside water.

Having good quality foam insulation for the cabinet of the hot tub is also essential for getting the perfectly warm water you are looking for. I know many Jacuzzis do not come with a pre-built insulator, but that is because the size of it highly depends on the surface of the tub and its surrounding environment.

Without a proper cover, not only you will lose heat, but you will also have to pay a lot more electricity bills as the heating elements of your hot tub will try to keep the water warm at all times. In normal conditions, the Jacuzzi uses electricity only for heating up the water, not constantly.

Steps to Fixing The Issue

When it comes to hot tubs, it usually takes a few hours to fix the water temperature issues. If the heating elements aren’t malfunctioning, there are a few easy steps that you can perform to solve the issue. They are mentioned below.

Step 1

One of the most common reasons behind this problem is the water level of the hot tub. Due to having high temperatures, the water of your Jacuzzi will start to evaporate and will lose a lot of density.

It can also happen for the displacement of aqua if you jump into the hot tub. The water will splash out and the level will go down significantly. A regular hot tub user won’t have a constant water flow system and thus the amount of water decreases significantly.

Now, there is a skimmer in your Jacuzzi. When it detects a lower amount of water than it anticipates, it will start sucking in the air and the temperature will further decrease. So keep the water topped up to get the comfortable warm bath you were looking for.

Step 2

If the previous step didn’t solve the issue, there is a high chance that the hot tub’s system was interrupted by air. It usually happens when you refill the tub in the wrong way or if you use the Jacuzzi with a low water level. If the Jacuzzi is airlocked, the flow of water will significantly decrease and thus the heater will not work.

There are ways to get rid of the locked air from your system. Some easy steps should fix the water temperature problem in no time. They are provided below.

  • To begin with, you will have to open the jets of the hot tub correctly. Always turn them clockwise, otherwise, the jets will break.
  • After that, turn down the heater. Then, disconnect it from the power source.
  • Then, turn on the jets and observe whether water is coming out. If so, then wait for a while and you should see some bubbles coming out along with water.

Now, if no water is coming out from the jets, but you can hear the pumps trying to push water out, then you may have a more serious issue. In such cases, do not keep the pumps running as they might be seriously damaged. Such airlocks can also be fixed.

  • First, you will have to lose the union. It is placed on the pump's suction side. After that, wait till water comes out.
  • After you see the water flow, just tightly attach the union again. If it is loose, the water will leak.

Then just attach the jets again with the hot tub and the problem should be solved.

Step 3

Now, if the water flow is lower than what you expect, and there is no airlock in the system of the hot tub, then properly clean the filters. The filter will catch all the specks of dirt and dust to keep the Jacuzzi water clean.

If it isn’t washed regularly, the filter might get clogged, and thus, the water flow will decrease. It is highly recommended to clean it every month and replace it once every 6 months. It is only 100 US dollars, so it wouldn’t be the worst idea to just buy an extra one in case of an emergency.

Common Mistakes People Make When Using Hot Tubs

Above, I have extensively discussed some of the most common reasons behind a malfunctioning hot tub. But they aren’t the only causes of not getting hot water from your Jacuzzi. Sometimes, some of our activities can drag the hotness of the water. Here are some mistakes people make before jumping to the conclusion that their hot tub is busted.

Not Giving Enough Time

There are a lot of people who don’t know the fact that it takes around 12 to 18 hours to get the perfect hot water from a Jacuzzi. It will vary depending on the hot tub you are using. For instance, if the heating materials are of great quality, you will get hot water sooner, otherwise, it can take up to 20 hours.

It also depends on where you live. In summer, a hot tub will be filled with perfectly warm water in no time. But, that’s not the case in the winter season. Check the manual provided by the manufacturer to know exactly how much time it takes. It would be wise to plug in the tub 20 hours before you use it.

Use of Air Blower

Adding an air blower inside your hot tub adds extra immersion to the whole bathing experience. I personally love to get in a Jacuzzi that has this feature. But every good thing comes with some drawbacks. It is pretty safe to say that an air blower will significantly reduce the temperature of the water.

Now, should you completely ignore this awesome feature to enjoy the water at the perfect temperature? Of course not. Using an air blower for around 20 minutes won’t make a significant difference to the hotness of the aqua. Just don’t keep this feature on for hours.

As you can see, the heating issue on hot tubs can occur for various reasons. “Why is my hot tub not heating up” is a common question, and in this article, I have tried to answer it as clearly as possible. Hopefully, after reading the whole article, you will be able to find the reason that is causing this issue. Until next time, bye.

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Written by Ferdi Vol
Ferdi Vol is a pool and hot tub owner who has been working in this industry for over 5 years. He has learned all the ins and outs of maintaining pools and hot tubs, as well as how to privately own one. Ferdi Vol is also passionate about blogging, researching topics that he shares with his readers online via this blog.
About Ferdi Vol
About Pool Uncle
Pool Uncle is a blog that focuses on helping pool and hot tub owners get the right tools, maintain their pools and hot tubs, and learn about how to care for them. It provides readers with all of the information they need to keep their pools clean, safe, and looking great. The website also publishes original articles about pool maintenance topics such as filtration systems or algae prevention techniques.
About the Author
Ferdi Vol has been in the swimming pool and hot tub as an owner for over 5 years. His experience ranges from owning a pools and hot tubs and maintaining them. He’s learned about pumps, filters, chemicals, cleaning products, treatment systems… you name it!
About Ferdi Vol
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