How Do Hot Tub Heaters Work?

By Jon Filson

Hydropool Hot Tubs and Swim Spas

Published May 15, 2024

There are usually two reasons why customers in our Hydropool stores want to know about heaters in hot tubs and 1) is because there are problems with the heater they have and 2) is because they are just curious.

If there’s a third that comes up, it’s due to circumstances like particularly cold winters in the area: People want to know what they are buying is going to stay warm and work year-round.

So we wanted to write this article about heaters!

We will go over:

  • Explain how hot tub heaters work
  • What are issues that can affect heaters in your hot tub?
  • How long do hot tub heaters last?

Hopefully by the end, you’ll have a strong sense of what that heater is doing underneath the shell and feel confident it’s going to keep your hot tub warm and toasty for as long as you decide to own it.



How Does a Hot Tub Heater Work?

Heaters known as “electrical resistance heaters” are fundamental to hot tubs.

These elements are responsible for generating heat. Essentially, convert energy from electricity into heated water.

Here’s how it breaks down:

  • Pressure pumps are responsible for pushing water through the assembly housing.  
  • As water makes its way through the heater assembly, it is heated by an element coil.
  • To disperse the warm water into the hot tub, the heated water is directed to a distribution box. Here, it makes contact with various jets where it is forcefully pushed through small nozzles which then pushes it into the basin of your hot tub.

This is the cycle that continues as long as your hot tub is plugged in. The heater operates unless it has been deliberately shut off or if your water has hit the temperature you have set it at.

What Issues Can Arise With Hot Tub Heaters?

If your spa isn’t performing as it should consider the problems mentioned below that could be plaguing your hot tub heater.

  • It is important to note that scale buildup can cause the hot tub heater to perform defectively. Scale reduces the heater’s generation of heat, which can cause malfunctions over time.
  • Dirty filters, clogged pumps, scale, corrosion and even the simplest thing as a loose hot tub cover can affect how well your hot tub generates heat and performs overall. Much like a swimming pool, a hot tub relies on clean filters, pumps and other components to function correctly.  When these are affected, your hot tub will not operate effectively.
  • Loose wires can also play a role in the malfunctioning of your hot tub.  It is important that cables are connected securely to avoid faulty performance. Similarly, chewed or melted wires can also affect how your hot tub performs.
  • Old age. A hot tub heater is a working piece of equipment. Like any piece of equipment, it can and will wear out with time.

How Long Do Hot Tub Heaters Last?

Most hot tub heaters will last at least five years, but stretching longer – up to 10 or more – is not uncommon. A new heater is usually around $500 installed, and parts like that are generally replaced, not repaired.

What Helps Your Hot Tub Heater?

The two things that will help your hot tub heater more than anything else are:

  1. Properly maintain your water. We know we said it already, but it should be stressed: Good maintenance habits will keep your hot tub running longer and lasting longer than anything else. Regular cleaning is key!
  2. Having quality insulation. Without proper insulation, your pump heater will have to work extremely hard. Quality hot tubs have good insulation, made for Canadian winters, which allows your hot tub water to stay warm because that heat gets locked in (Hydropool’s hot tubs have vents that are closed in the winter to lock heat in and keep your hot tub water warm).

How Does a Hot Tub Heater Work?

A hot tub heater works by having electricity heat up a coil inside an area where water is forced through. That heated water is then distributed through the hot tub, warming all over the water, until it reaches the temperature you’ve set.  

Hot tub heaters serve a core purpose. As a result, they must be maintained consistently. If not, you risk the chance of causing permanent damage to your hot tub.

They also wear out, like any working part in a machine. So if you own your hot tub for a long time, there is a chance you’re going to have to deal with a heater issue at some point.

We hope we answered all your questions about heaters and hot tubs today, but if we missed one, don’t hesitate to reach out to one of our local retailers here.

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