Please note, the rankings below are based on the opinion of Poolonomics staff and are in no way related to Amazon’s own rating or review system.

Preview Product Price
Hayward CSPAXI55 5.5 Kilowatt Electric Spa Heater Hayward CSPAXI55 5.5 Kilowatt Electric Spa Heater from $518.99
Hayward H150FDN Universal H-Series 150,000 BTU... Hayward H150FDN Universal H-Series 150,000 BTU... from $1,482.88
EcoSmart SMART POOL 27 Electric Tankless Pool... EcoSmart SMART POOL 27 Electric Tankless Pool... $902.63
Hayward H100ID1 H-Series 100,000 BTU Above Ground... Hayward H100ID1 H-Series 100,000 BTU Above Ground... from $1,123.14
Sta-Rite SR333NA Max-E-Therm Pool And Spa Heater,... Sta-Rite SR333NA Max-E-Therm Pool And Spa Heater,... $2,199.89
OrangeA 11KW 220V Pool Heater Thermostat Swimming... OrangeA 11KW 220V Pool Heater Thermostat Swimming... from $178.99

Introduction

You need a way to keep the water in your tub at the perfect soaking temperature throughout the year.

Because let’s face it, when the temperature outside drops, without heat, you’re not going to get any use out of your brand-new hot tub.

In this article, I’ll explain the different types of hot tub heaters, what you should consider before buying, and make a couple of recommendations on the best products in the market.

How A Hot Tub Heater Works

When you buy a new hot tub, it’ll typically come with a heater, which is a relatively simple but important bit of technology.

Connected into the pump system of your hot tub, a hot tub heater has a heating element inside that raises the temperature of all the water that flows through it. Of course, there is also a failsafe, a cut-off switch that turns the heat off if it reaches over 104 degrees.

Depending on the model you have, there will also be a control panel to select your ideal temperature for the water. The heater will use sensors like a thermostat and adjust the heating levels accordingly to ensure your hot tub remains at the temperature you’ve set.

Hot Tub Heater Types

Hot tub heaters come in a variety of forms, each with their own unique features, build quality and wildly different price-points to boot.

In this section, I’ll cover the different types you can buy as well as the benefits and drawbacks of each.

1. Electric Heater

Electric hot tub heaters are also called flow heaters, as they pack the heating elements along a length of stainless-steel tube, heating the water as it flows into your hot tub.

What’s great about these heaters is they’re budget-friendly and are quite simple to install. It connects right into the pump system of your hot tub and plugs into a power outlet, drawing electricity which it uses to heat the pipe and drive your water temperatures up.

However, the ongoing running costs of an electric heater can be high, especially if you live in a cold climate.

Without a well-insulated hot tub, it can take a long time for an electric heater to hit the set temperature, and it can struggle to maintain it. Ultimately resulting in longer running times for the heater, and a higher electric bill.

2. Gas Heater

If you’ve got a gas line to your home already, installing a gas heater becomes a viable option. Some models run on both natural gas, others on propane. If you don’t have a gas line, it’s still a possibility, but extending a gas line just for a hot tub becomes very costly, very fast.

Gas heaters are typically used in larger hot tubs that have been installed in-ground, as the most significant advantage of these is how fast, and effectively they operate.

With a gas heater, it becomes possible to set a lower “resting” temperature, then bump up the heat when you’re planning to use your hot tub. How quickly it does that will depend on the heater you’ve bought, the size of your hot tub and the resting temperature set, but it’s usually pretty quick (typically under an hour).

What you will need to consider is just how big these particular heaters can be, and remember they will need to be installed outdoors (for adequate exhaust and ventilation).

3. Solar Heater

Solar heaters allow you to heat your hot tub in an eco-friendly way and also cut down on the ongoing running costs as it harnesses the power of the sun to warm the water.

Most solar heaters for both pools and hot tubs push the water through a series of pipes that are heated from the warmth of the sun before it’s sent right back into your hot tub. They connect into the existing pump system and must be positioned in a sunny spot in your yard.

Solar is a viable option when the sun is out, but it’s important to remember you’ll need the sun for it to keep working. So, at night (or during winter), the effectiveness of this system goes right down. Not particularly ideal if you want to use your hot tub during these times.

Which Type is Best?

Ultimately the best hot tub heater for you will depend on your location, and how you plan to use your hot tub throughout the weeks and different seasons of the year.

If you’re in a mainly sunny area and generally like to soak in your hot tub during the day, a solar heater could be ideal. It’s certainly got the lowest ongoing running costs. But if it’s not getting the water hot enough, you should consider an electric or gas model.

For mild climates, an electric heater is a cheap and viable option. Though if you live somewhere with a cold winter, I’d actually recommend investing in a gas heater instead, as it’ll work out cheaper (in the long run) because it’s a more efficient heating system.

What To Consider Before Buying

Knowing which type to look for will narrow down your options, but it doesn’t help you measure the nuances that make or break a product.

Let’s go over some of the key aspects to look out for when buying a hot tub heater.

How Quickly Does It Heat The Water?

The speed at which a particular heater works is critical because the less “time” your heater is running for in a specific month will result in a lower ongoing heating cost.

Performance of a heater is usually measured in kilowatts, so an 11kw heater is going to be twice as powerful as a 5.5kw heater. If you’re looking for a heater to bring your hot tub up to working temperature rapidly, look for the highest kilowatt performance level.

Generally, it’ll take anywhere from 6 to 12 hours to heat a hot tub from cold, though you’re probably only going to do this once or twice a year. Gas powered heaters will usually heat the fastest, followed by electric and solar.

Does It Maintain A Constant Water Temperature?

Look for a heater that has a thermostat to monitor and react to any changes in the water temperature, to ensure your hot tub is always perfectly heated when you need it.

I should also mention here that a cut-off switch is an important safety feature, cutting off the heater should the water get too hot. That way, you reduce the risk of injuring yourself in overheated water or doing any damage to the components inside your hot tub.

Is It Compatible With Your Hot Tub?

Not all heaters are compatible with every different model of a hot tub, so make sure you’ve done your research and perhaps even confirmed with the manufacturer of your hot tub that the new heater is suitable.

The size of the heater, as well as all the connectors and fittings will need to be compatible with your hot tub,

How Difficult Is It To Install?

Depending on which particular heater you’ve bought, installing it ranges from a simple do-it-yourself solution to having a professional install it for you. Solar heaters and even electric models are the most straightforward options, just follow the guides with the product to connect these in.

Gas heaters, on the other hand, will need to be connected into an existing gas line, installed in an area with adequate ventilation, and may even require professional installation.

How Long Will It Last?

You can expect a heater for your hot tub to last around 5 years. Look to the warranty of any product you buy, and make sure you’re also taking care of your hot tub and maintaining the system, this will help to extend the life of your heater.

Best Hot Tub Heater Reviews

So far we’ve covered what a hot tub heater, why you need it, the different types available, and what features to look out for.

In this section, we’ll be looking at specific products, each of which were hand-picked for review based on the same criteria above.

Let’s dive right in.

#1. Hayward CSPAXI55 Heater

Hayward CSPAXI55 5.5 Kilowatt Electric Spa Heater
Hayward CSPAXI55 5.5 Kilowatt Electric Spa Heater

    This is our runner up for the best hot tub heater.

    Designed by Hayward, this is a 5.5kw electric spa heater that is compact enough to fit in behind a hot tub skirt or even under the steps at just 13.8 x 10.7 x 8.6 inches.

    Featuring a stainless-steel tank and stainless-steel threaded head, you also get a heat-on indicator light, so you know when it’s on and running.

    What I like best is the easy access you have to both the control panel and internal elements, which makes any future maintenance or repairs very easy. The biggest downside is the 30-day return policy, and that it can take a while for the smaller sized unit to heat the water.

    Pros:

    • Available in both 5.5 and 11kw models
    • Easy to install and connect to your hot tub

    Cons:

    • Lower kilowatt model takes longer to heat the water
    • Some users had problems with returning faulty products

    #2. Hayward H150FDN Heater

    Hayward H150FDN Universal H-Series Heater
    Hayward H150FDN Universal H-Series Heater

      Designed by Hayward, this is a gas hot tub heater, available in sizes from 150,000 BTU to 500,000 BTU (roughly equivalent to 44kw to 147kw in an electric model).

      Featuring a patented cupro nickel heat exchanger, this is a highly reliable product that is not only energy and cost efficient to run, but it’s also easy to use with the LED control panel display.

      What I like best is the low NOx emissions from this particular model, perfect if you’re in an area that has restrictions for air quality emissions. The biggest downside is you may void the warranty by installing it yourself, and some users experienced faulty fuses and mechanical failures just a few months after receiving the product.

      Pros:

      • Reacts immediately to changing water temperature
      • Designed to heat your hot tub fast

      Cons:

      • Some users had problems with the fuses
      • Warranty is voided if you install it yourself

      #3. EcoSmart SMART POOL 27 Electric Heater

      EcoSmart SMART POOL 27 Electric Heater
      EcoSmart SMART POOL 27 Electric Heater

        Designed by EcoSmart, this is an electric hot tub heater operating at 27kw and is remarkably compact, with a product size of just 6 x 14 x 17 inches.

        Featuring a tankless system and the latest flow sensor technology, this particular heater uses a digital thermometer to ensure your hot tub is always heated correctly.

        What I like best is how easy this heater is to install either as a replacement heater or a new system, and that it’s incredibly compact. The biggest downside is it doesn’t have a waterproof cover to protect it outside, and the ongoing running costs are quite high.

        Pros:

        • Comes with a 2-year warranty
        • Easy to install to your hot tub
        • A highly compact tankless system

        Cons:

        • Takes significant energy to run
        • The cover isn’t waterproof

        #4. Hayward H100ID1 H-Series Heater

        Hayward H100ID1 H-Series Heater
        Hayward H100ID1 H-Series Heater

          This is our choice for the best hot tub heater.

          Designed by Hayward, this is a gas hot tub heater that operates at 100,000 BTU, which is approximately equivalent to 29kw, though it will need a power source for ignition.

          Featuring induced draft technology to ensure effective heating in all weather conditions, the plug-in 120-volt electrical cord makes for easy installation once the gas is connected.

          What I like best is the cover, even while it’s running the heater is cool to the touch, making it a safe addition to your yard. The biggest downside is the longevity, it’ll last an average of 4 to 5 years, and some users had problems with the internal components giving out.

          Pros:

          • Heater remains cool to touch when operating
          • Cost effective to run month to month
          • Suitable for even adverse weather conditions

          Cons:

          • Not recommended for use over 2,000 feet above sea level
          • Some users found the internal components fail too easily

          #5. Sta-Rite SR333NA Pool/Spa Heater

          Sta-Rite SR333NA Max-E-Therm Pool/Spa Heater
          Sta-Rite SR333NA Max-E-Therm Pool/Spa Heater

            Designed by Sta-Rite, this is a lightweight gas heater, that is available in sizes from 200,000 BTU, 333,000 BTU and 400,000 BTU (equivalent to 59kw, 98kw and 117kw respectively)

            Featuring dual thermostat controls with a LED temperature display, the outside casing is constructed from Dura-Glas, an exclusive material to this brand to help protect the heater from all weather conditions.

            What I like best is how compact it is, compared to other heaters that run at the same BTU, and it’s quite easy to install. The biggest downside is the durability, many users had products fail at the 2-year mark, and the warranty is for only 60 days.

            Pros:

            • Lightweight and compact
            • Easy to install

            Cons:

            • The 60-day warranty is not enough
            • Expected lifespan is shorter than other models

            #6. OrangeA 11KW 220V Heater

            OrangeA 11KW 220V Heater
            OrangeA 11KW 220V Heater

              Designed by SteamSun, this is an 11kw electric hot tub heater, which is very compact and perfect for sitting alongside your hot tub at just 4.7 x 22 x 14.9 inches.

              Featuring an aluminum coated plate housing, this heater uses temperature sensors instead of the traditional magnetic flow switch to keep your water heat levels constant, and shut the heating off should any malfunction occur.

              What I like best is the constant monitoring system in place on this heater, and the intelligent self-diagnostic function you can use to correct any issues. The biggest downside is after a power outage, the selected temperature will reset to 104 degrees, and you may also notice up to a 3 degree variance in your water temperature to what’s been set.

              Pros:

              • Slim design helps install out of sight
              • Intelligent self-diagnostic function

              Cons:

              • Temperature resets to 104 degrees as default
              • Will vary 3 degrees above/below set temperature
              • High ongoing running costs

              Conclusion

              Choosing the right heater for your hot tub will depend on not only where you live and the local weather conditions, but the way you intend to use your hot tub.

              Make a smart choice, and your hot tub water will be perfect for a soak, whenever you plan to use it.