What is the best method to heat my DIY Hot Tub in 2025?

What is the best way to heat my DIY Hot Tub? This is a question that many people ask about their hot tub and rightly so. Heating is a major part of your hot tub setup and also one of the most costly. So having a little bit of knowledge on different heating methods goes a long way. 

In this blog post, we will discuss various ways to do just that. We will look at the advantages and disadvantages of each method. Let’s get to it!

 

Why do I still need a Spa Pack?

Before we start, it should be noted that all of the methods that I am going to talk about below need to be used in conjunction with a Spa Pack. A Spa Pack will contain its own heater (it is no more economical to purchase one without a heater).

The Spa Pack is important as this will control the jets as well as the filter and purge cycles. Both of which are important to keep the water circulating and keeping that hot tub water crystal clear.

Any of the methods below run in series in the plumbing, so they will sit after the Spa Pack and in line so the next step for the water is then the jets and back into the hot Tub.

 

Electricity

We will first start with the all-time favourite, electricity. Electricity is the easiest to install in your DIY Hot Tub. Whilst you may need an electrician, in fact you should use an electrician for the install, it is just a matter of running the correct cable from your breaker box to the tub location.

This method is also more convenient because of its availability and no need to store external fuel as well as lower initial costs. 

The downside of using electricity is that it is slow to heat up the tub. If you are looking for a quick heat up time for an impromptu dip, then electricity is not for you.

With the post 2022 hike in energy prices, electricity has however become much more expensive than it was so perhaps electricity might not be a very wise choice in 2025. 

Propane

Next we’ll talk about propane. For propane you either need to have a supply line to your property, or you need to have a large tank in your garden. Propane heaters work best when they’re hooked onto some sort of gas line from inside the house but if that is not possible, then a tank in the garden will suffice.

The downside of propane heaters is that it can be expensive to buy fuel for and the tanks have a limited life span so you’ll need to replace them after some time. On the plus side, if you buy a large enough tank it is going to last you for a number of months so you don’t need to refill it that often.

The other thing about using propane is that there are more fumes released from burning gas which means your hot tub heater needs ventilation. Therefore, this is not a good option if you are looking to enclose your DIY Hot Tub unless the heater itself can be located outside.

Perhaps the biggest advantage of Propane (and natural gas below) is the speed that it will heat up your tub. It is by far the fastest way to heat up a Hot Tub. Looking for an impromptu dip, this (or natural gas) is the heating method for you.

Natural Gas

The best and most environmentally friendly way to heat a DIY hot tub is by using natural gas. Unlike propane, natural gas doesn’t emit any fumes, so it’s perfect if you’re looking for an alternative that won’t affect the environment nearly as much as propane.
A great thing about this type of heating system is that they don’t require ventilation because there are no harmful chemicals being released into the air from them when they burn, unlike with propane tanks, which can be dangerous or not ideal in certain circumstances such as indoor tubs.
The other great thing about using natural gas as opposed to propane is how much cheaper it tends to be per month because these types of heaters use less energy than others do.

How to Install Natural Gas Heating on a Hot Tub:

• Purchase a gas-powered heater specifically designed for hot tubs or spas.
• Ensure your hot tub is equipped with the necessary plumbing and electrical connections to accommodate the gas heater.
• Hire a licensed gas technician to run a gas line from your home’s main supply to the hot tub location, ensuring proper sizing and installation of safety valves.
• Connect the gas line to the heater, and hook up the plumbing and electrical systems as required.
• Test the system for leaks and check that the heater is functioning properly before use.
• Confirm compliance with local regulations and codes for gas appliance installation.

Air Source Heat Pumps

Next, we are going to look at Air Source Heat Pumps.

An air source heat pump is the most efficient way to keep your hot tub at a comfortable temperature. Depending on your location, you can see savings of upto 60%. With the high energy prices, it’s a great alternative going into 2025.

It doesn’t have the speed of Propane or Natural Gas but doesn’t have the cost of electricity and is much faster. I have a full article on Air Source Heat Pumps Here but I wanted to mention that the only real downside to these is that the initial hardware costs tend to be quite high.

Solar Heating for DIY Hot Tubs

Every once in a while I do get asked about Solar Heating. 

If you have access to enough sunlight throughout the day (at least six hours worth) and don’t mind having them installed on your property permanently then solar panels might just be what you’re looking for in order to power your DIY Hot Tub.

The downside to solar panels for heating your hot tub are that you will need to have enough sun exposure during the day in order for them to generate heat. You’ll also need a way of storing that generated energy so it can be used overnight when there isn’t as much sunlight.

So, think of how many batteries you are going to need to be able to output 40-50A of electricity. How consistent can your supply be – that depends on how much sun you are getting and how much you are going to use your hot tub.

At first, solar panels may seem like an expensive option but they are about as efficient with their heating ability and require virtually no maintenance!

The downside is that you are going to be running an electric heating method from this which can be slow asI have already mentioned.

That said, if you have all this “free electricity” then you probably don’t care and will leave your Hot Tub at temperature all the time.

In Conclusion

There’s not one best way to heat your DIY Hot Tub – each system has its own advantages and this table gives your a summary of the methods outlined above:

Heating Method	Energy Source	Initial Installation Cost	Operational Cost (per month)	Efficiency	Environmental Impact	Installation Complexity	Heating Speed	Lifespan
Electric Heater	Electricity	$$ – $$$	$$ – $$$	High (90%+)	Higher emissions if using non-renewable sources	Moderate (requires electrical work)	Moderate (slow to heat large tubs)	5-10 years
Propane Heater	Propane Gas	$$ – $$$	$$ – $$$	Moderate (~80%)	High emissions (fossil fuel)	Moderate (requires propane tank installation)	Moderate (heats faster than electric)	5-10 years
Natural Gas Heater	Natural Gas	$$ – $$$	$ – $$	High (~90%)	Lower emissions than propane, but still fossil fuel-based	High (requires gas line installation)	Fast (heats quickly)	10-15 years
Air Source Heat Pump	Electricity (via air)	$$$	$$	Very High (300-400%)	Lower emissions if powered by renewable electricity	High (requires both electrical and plumbing work)	Slow (takes longer to reach desired temp)	15-20 years
Solar Heater	Solar Energy	$$$$	$	Very High (efficiency varies with sun)	Zero emissions, renewable energy	High (requires installation of panels, pump, and plumbing)	Slow (depends on sunlight)	20+ years

A quick summary of each of these heating methods is:

• Electric Heater: Easier to install but more expensive to run if you’re in an area with high electricity costs. Heating time is slower, and efficiency is high, but it’s not as environmentally friendly unless using renewable energy sources.
• Propane Heater: Moderate in both cost and heating speed, but it’s less efficient and has a higher environmental impact due to fossil fuel use.
• Natural Gas Heater: Similar to propane in terms of heating speed but generally cheaper to operate and more environmentally friendly than propane, although still a fossil fuel.
• Air Source Heat Pump: Very efficient and environmentally friendly if using renewable electricity, but the initial cost is higher and heating time is slower, especially in cold climates.
• Solar Heater: The most environmentally friendly option with zero emissions and free energy, but it has the highest upfront cost and slow heating time, heavily dependent on sunlight.

Each of these options has its pros and cons, so choosing the right one depends on factors like local energy costs, environmental goals, and how quickly you want to heat the tub.

A few more things before we wrap up: First off, don’t forget about insulation when building your DIY Hot Tub! Insulation will make sure that whatever power source you use stays warm for as long as possible, which in turn makes sure that the heat you are putting into the tub stays in the tub longer.

Environmental conditions, geographic location, amount of use, the cover you use all attribute to the heating of the Hot Tub. Take the information in this post and think how it might be affected where you are.

Any questions, as always, please do get in touch.

Thanks for reading

Happy Hot Tubbin’

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Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Today, I've helped over 1000 DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi