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How does a spa heater work?

There’s nothing like soaking in warm water on a cold evening, making your spa's heater essential! This guide covers how spa heaters work, types, costs, and tips for efficient heating year-round.

spa heater

A spa heater keeps your water warm and comfortable, making every soak enjoyable.

But how exactly does a spa heater work? From the types of heaters available to their cost-effectiveness and energy efficiency, understanding these details can help you choose and maintain the best system for your spa.

Key Takeaways:

  • Spa heaters come in three types: electric heaters, heat pumps, and gas heaters.
  • Heat pumps can reduce heating costs by up to 75%.
  • Running a spa heater costs about $3 per day.
  • Spa heaters range in price from $400 to over $1000.
  • Circulating water evenly helps maintain consistent spa warmth.

How does a spa heater work?

The most common types of spa heaters have an electric element encased in a tube. The water from your spa travels through the tube and gets heated as it passes across the element.

The warm water is then circulated throughout your spa by your circulation pump which moves the warm water evenly throughout your plumbing and out into your spa water.

What are the types of spa heaters?

Spa pools typically feature three main types of heaters, each designed to enhance your spa experience by efficiently heating the water to your preferred temperature.

Here’s a breakdown of the options available:

Immersion Element Heater

Typically, every portable spa pool comes with an immersion element heater. An immersion element heater is an electrical heater that sits within a stainless steel or plastic tube attached to your spa plumbing and controller.

The size of this element depends on the power supplied to your controller. Some spa controllers have a variable output heater that can be set depending on the size of the circuit supplying power to the spa.

How do I know if my spa heater element is bad?

For example, if your spa requires only 10 amps, it will likely have a heater element rated between 1.5 - 2.0 kilowatts. This indicates the amount of heating power the controller/element provides for the spa.

If your spa has a small heater and holds a large volume of water, it will take longer for the heater to reach the desired temperature or maintain it while in use.

If your spa has a 32-amp power supply, you could have a heater of up to 6.0 kilowatts. Given the same water volume, your spa could heat up to three times faster than a 10-amp spa with a 1.5 - 2.0 kilowatt heater.

Heat Pumps

Heat pumps work similarly to air conditioners and provide an efficient way to heat or cool your spa. In the right conditions, a heat pump can save up to 75% on heating costs compared to immersion heaters.

A heat pump can also deliver more heating power, allowing for quicker heating of the water with less energy consumption.

spanet heat pump

For example, a 10-amp spa could run an 8.8-kilowatt heat pump compared to a 1.5 - 2.0 kilowatt immersion heater. Some heat pumps come with their thermostat control, while others, like the SpaNet®, communicate directly with the controller for seamless heating and cooling integration.

Click the button below to learn more about the key differences between a heat pump and a heater element.

Spa pool heaters vs spa pool heat pumps

Gas Heaters

Gas heaters can heat a spa quickly; however, to our knowledge, no gas heaters are compatible with spa controllers.

gas heater for spa pools

Additionally, unlike heat pumps, gas heaters do not offer cooling functionality. For these reasons, we consider heat pumps a superior choice.

Pros and Cons of Spa Heaters

To provide you with a summary of the advantages and disadvantages, here’s a comparison of each type of spa heater:

Heater Type

Pros

Cons

Immersion Element Heater

  • No installation is needed as it comes installed with your spa
  • Precise temperature control
  • Higher long-term operating costs
  • Slower heating compared to gas

Heat Pumps

  • Most energy-efficient option (up to 75% less energy usage)
  • Can cool and heat water
  • Long-term cost savings on energy bills
  • Higher upfront cost
  • Takes up space
  • Requires professional installation

Gas

  • Fast heating (can heat water in about an hour)
  • Good for infrequent use (e.g., holiday homes)
  • Higher fuel costs
  • Complex installation
  • No cooling capability
  • Not compatible with spa controllers

Are spa heaters expensive to run?

When evaluating whether spa heaters are expensive to run, it's important to consider the operational costs associated with different types of heaters. Here’s a breakdown of their running costs.

Immersion Element Heaters

  • Power Consumption: Typically around 3 kW.
  • Running Cost: Approximately $0.80 NZD per hour (based on an electricity cost of about $0.24 AUD per kWh).
  • Daily Usage: 2 hours×0.80 NZD hour=1.60 NZD day or approximately $48.00 NZD/month.

Heat Pumps

  • Power Consumption: Generally more efficient, using about 1 kW, but can vary based on model and usage.
  • Running Cost: Estimated at around $0.40 AUD to $0.60 AUD per hour
  • Heating Capacity: Offers significantly higher heating capacity compared to traditional models, typically providing over double the output, such as 8.8 kW versus 3 kW. This means a faster heating time and better efficiency, especially for larger volumes.
  • Daily Usage: If used for about 4 hours daily, the cost would be around:
  • 2 hours × 0.50 AUD hour = 1.00 AUD day or approximately $30 AUD/month.

To get a more accurate calculation of heat pump operating costs, you can use our Heat Pump Calculator.

Heat Pump Calculator

Brand
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Model
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Litres
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Location
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Choose Heat Pump Model

Save Up To
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10 YEARS
Pay Back Time
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YEARS
Model
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RRP
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1 Year
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2 Years
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3 Years
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5 Years
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10 Years
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** This heat pump calculator is for general estimating only. Running costs will vary depending on use, installation, location, and climate.

Individual results may vary.**

The data used in this calculator may change without notice.

Savings are calculated based on replenishing 6°C of heat loss per day using the model's literage, local annual average temperatures, and a holding temperature of 37°C.

Swim spa water temperature is usually held at lower temperatures than 37°C, which will increase the ROI and reduce the payback time. This is not reflected in the calculator.

Gas Heaters

  • Power Consumption: Varies based on the model, but typically gas heaters can heat water quickly and may use around 200 MJ/day, translating roughly to about $1.50 to $2.50 AUD per day depending on local gas prices.
  • Running Cost:
  • Approximately $3.50 NZD/day, leading to around $105 NZD/month.

In conclusion, immersion element heaters can be costly to operate because they rely heavily on electricity, especially with frequent use. Heat pumps are a more energy-efficient option but can still have high costs based on how often they're used and local energy rates. Gas heaters can also be expensive, but they tend to heat water faster and more efficiently in some situations.

In Summary

Spa heaters are essential for maintaining a comfortable, relaxing spa experience. We hope this article has provided you with a clear understanding of how different types of spa heaters work, their costs, and how to choose the right one for your needs.

Got more questions? We’re here to help!

Contact Spa World

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