DIY Hot Tub Heater

DIY Hot Tub Heater

DIY Hot Tub Heater – which one should I choose? How you heat the hot tub can ultimately affect how you use it and how much it costs you to run your tub. As I am sure you have realised, this blog and my YouTube Channel focus on DIY Hot Tubs and Pools. Hopefully, in this article, I can explain some of the options that you have for your DIY Hot Tub Heater.

DIY Hot Tub Heater – The Electric Spa Pack

The Spa Pack that is at the heart of your hot tub actually has an electric heater inside it. Many people don’t actually realise this but pretty much all suppliers include one. This means that if you are just going to use electric to heat your hot tub, then you already have an electric heater.

The spa Pack itself is an essential piece of kit in terms on controlling the jets, the air blower and of course the filtration cycles.

The downsides to electric being use as a DIY hot tub heater is the heat up speed which can be very slow and the cost. At time of writing, the electric costs World Wide have increased dramatically so people are looking for cheaper alternatives for their hot tub heating. However, the Spa Pack still remains the simplest way of heating a hot tub.

DIY Hot Tub Heater – wood burning

There are many occasions where having an off grid heating method for your hot tub is ideal. However, the main things to think about here are that if you are off grid, you are not going to have any pumps or jets. If you have no pumps or jets, then you are not going to have any filtration. With no filtration, you essentially have a bath that you are going to be emptying after every use.

The other thing you need to be mindful of here is that there is no thermostat. You are relying on the fire getting the tub to the right temperature and then being able to maintain it without “cooking you” – it is a challenge, believe me!

The amount of time needed to heat by a wood burning fire can be considerable if you have a large tub. Also, the amount of “work” involved in building the fire every time you want a hot tub can be too much for me (me included!)

Yes, it is certainly cheap, but it is not convenient in the slightest and you must have a lot of time on your hands.

What About Fire Pit Coils?

Firepit coil as a means of DIY hot tub heating are a step up from the basic wood burner. They do involve in most cases a pump which will circulate water through the coil and it absorbs the heat and then takes the hot water back into the tub.

They are certainly more efficient than the regular wood burner and quite often can be used as an auxiliary means of heating a hot tub.

With pumps comes filters and clean water so this in my opinion is a much better method of heating. However, you still have the task of building and maintaining the fire, which when you are in the tub itself, can be a challenge.

DIY Hot Tub Heat Exchangers

Heat Exchangers are a great way in which you can harness heat that you are already generating or paying for in your home and then direct that into the tub. They essentially connect to your hot water or heating system of your home.

The hot water circulates around the heat exchanger heating up the “tubes” inside and then the heat gets transferred into the hot tub water that flows through the centre of the heat exchanger. A very simplistic explanation here but you get the idea. The waters of course do not mix – the hot tub water absorbs the heat offered by the heat exchanger.

Heat Exchangers are very efficient in that you are already heating either your hot water or your radiators or under floor heating in your home. In short, you are not paying twice to heat anything. They are also very good at putting out a lot of heat from a cost-effective unit. They are not expensive at all in terms of the heat that they will generate.

Heat Exchangers are usually added as a secondary form of DIY Hot Tub Heating as they are only useful for heating when you are using your home’s boiler. Therefore in the summer, they will be somewhat redundant.

The Fastest DIY Hot Tub Heater – Propane and Natural Gas

The more traditional way of heating a hot tub or a pool is with a gas or propane heater. They remain the fastest ways of heating up the tub being able to output a huge amount of heat.

However, with the cost of fossil fuels on the increase World Wide, many of us are looking for more efficient cheaper to run alternatives to propane and natural gas. However, these alternatives still are nowhere near as fast to heat up the tub.

If speed alone is what you are looking for, then propane or natural gas is for you.

The Most Economical DIY Hot Tub Heater – Air Source Heat Pumps

If you have read any other articles or watched my videos on the YouTube channel, they you will know that I am a big fan of Air Source Heat Pumps.

For me, this was the game changer for my own hot tub usage. I benefitted for 8x heat up speeds over the electric heater I used to use and I also saw a drop in the running costs by 66%. For me, this was win win!

Whilst Ait Source Heat Pumps do become less efficient in the colder months, being able to put 1KW of electricity in and get 6KW out for me was a no brainer. This “in” versus “out” is known as a COP – Coefficient of Performance.

This number will tell you that if you put in XKW of electrical energy, you are going to get XKW of heating energy out. The higher the COP the more efficient the unit.

For me – Air Source Heat Pumps are the way forward and you can see the brands that I promote below.


Ultimately, the DIY Hot Tub Heater that you choose needs to fit you and your hot tub. It needs to fit how you plan to use the hot tub. If you are looking for speed of heat up, then electric is not for you. If you are looking for the easiest integration, then electric will be your choice. If you are looking for some hard work but cheap heating, then go for the fire pit – but watch those temperatures.

For me, I chose an Air Source Heat Pump for my own hot tub. It saved me a lot of money (66%!) on the running costs of my tub. It fits my usage as it only takes a 90 mins or so to heat up which is ideal for how I use the tub. It will also maintain the heat in the tub too.

Hope you have found this article useful. If I can help you with your own DIY Hot Tub Heater, then please do get in touch.

Happy Hot Tubbin’