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What size heat pump should I buy for a swimming pool?

7 min läsa
Insights heat pump size

Heat pumps have quickly become the water temperature control solution of choice for swimming pools. When it comes to comfort and usability, water temperature is a key consideration for all pool owners and managers. As energy usage and the subsequent environmental impact has become a focal point for users the most efficient and reliable systems are in high demand.

Calorex heat pumps effectively and economically heat and cool swimming pools, almost regardless of ambient air temperature and location. The size and type of heat pump you need will depend on a range of factors, which we will explore throughout this article.

Why choose a heat pump for heating a pool?

Calorex heat pumps are specifically designed for swimming pool water heating and cooling. The components they are constructed with are designed to maximise reliability and efficiency even in the most varied and toughest of swimming pool climates.

How heat pumps enhance the swimming experience

When water is too cold or too warm, conditions can become too uncomfortable for swimmers and deter them from using the pool facilities. Consistent and steadfast pool temperature control is therefore critical to keeping it in use year-round.

In the case of a residential pool, the wrong temperature can be a major inconvenience to your personal comfort. If your pool is commercial, it could have a negative effect on the business and the health of the individuals who use it.

Keeping pools warm in winter

Winter temperature drops lead to water evaporation in swimming pools and excess heat radiation. This causes heat loss which must then be replaced through heaters to keep temperatures maintained.

Staying cool in summer

During warmer months, swimming pools are exposed to significantly higher levels of sunlight and heat. When high ambient humidity is also present it creates a difficult swimming environment because pools are unable to cool down through the process of evaporation.

This creates undesirable swimming conditions that leave users unable to enjoy the water because of excessively high heat levels. Heat pumps work to cool in warm conditions and climates so they are an effective way to negate this issue.

How does a swimming pool heat pump work?

Swimming pool heat pumps provide the most energy-efficient method of heating and cooling. They achieve the temperature you need while saving up to 75% in operating costs.

A heat pump uses electricity and refrigerant to pass heat from one location to another. It extracts heat from outside the pool (in the low pressure side) and transfers it to the refrigeration coolant. The coolant compresses and the temperature increases.

With the coolant now hot, the heat is moved to the pool water side of the heat pump (the high pressure side). This passes pool water over the pipes containing the hot coolant and subsequently increases the pool water’s temperature.

Inverter heat pumps vs. on/off heat pumps

There are two primary types of swimming pool heat pump that both run off similar operating principles. They extract heat (energy) from the air and pass it to the pool water to increase the temperature. Each heat pump includes three core components: an evaporator, a compressor and a heat exchanger.

On/off heat pumps

This technology has been around for several decades and has long been the go-to choice for swimming pool temperature control.

The disadvantage of on/off heat pumps when compared to inverter heat pumps is that this relies on the compressor running with constant speed (maximum) under a fixed frequency. The frequency can vary for different requirements, but is usually around 50Hz/60Hz. With this method, the compressor needs to be turned on/off many times during operation and always running with maximum noise level - to keep the pool temperature at the right level.

The inverter heat pump can work in a much wider frequency range of 20Hz to 100Hz. The frequency is automatically adjusted depending on the ambient temperature and what the desired pool temperature should be.

Inverter heat pumps

Despite inverter heat pumps being a relatively new technology, they have been adopted more widely in recent times due to their energy efficiency.

But what makes them so energy efficient? As the fan and the compressor are able to run at different speeds, this means the heat pump is able to acclimatise to reach the right temperatures more quickly and accurately.

Once the pool hits the right temperature, the heat pump is able to reduce its power usage by 25%-50%. With that level of output, this delivers a Coefficient of Performance (COP) of just over 13. This means an inverter heat pump can generate 13kW of pool heat for every kW of electricity it consumes. They only use the energy they absolutely need to, and only when it is required.

Our Calorex inverter heat pumps are twice as efficient as traditional on/off heat pumps, reducing energy usage and increasing heat production. They also work efficiently from temperatures as low as -10°C. This is great news for outdoor pool owners, meaning you can extend the pool season much further than you could with traditional methods.

Factors that affect the size of a heat pump

The size and type of heat pump you need will depend on a number of factors, including:

  • How big the swimming pool is

  • Whether it’s indoor or outdoor

  • The temperature and climate of your environment

  • Ceiling height (if indoors)

  • Whether the pool is above ground or below ground

  • The pool’s thermal properties and insulation

How the size of the swimming pool influences which heat pump to get

You will see lots of guides and calculators online that can roughly calculate what size heat pump you need, but it’s important to remember that they should only be used as guides only. The factors outlined above will all greatly influence what kind of heat pump you will need to effectively heat and cool your swimming pool.

Below is a very loose, rough guide to what the heat output would need to be to effectively heat 4 different sized pools. But again, this would depend on a number of factors. Our experts at Calorex can help you make the most effective decision and purchase possible – in terms of both power and cost.

Pool Volume (Liters)

Heat Output (kW)


Of course, the bigger the pool, the more power it will take to heat it. That’s why we offer a range of small and large heat pumps to cater for residential and commercial-sized pools.

What does a heat pump cost to operate?

The long-term return on investment far outweighs the initial one-off investment for the purchase of the equipment. The energy efficiency of our units gives you cheaper running costs and helps you keep pool facilities open for longer periods of time throughout the year.

When you invest in an inverter heat pump, you will be using up to half the energy you would use with a traditional on/off model, and one tenth of what an equivalent gas or electric pool heating solution will use.

Heat pump solutions from Calorex

Our range of swimming pool heat pumps offer eco-friendly and effective heating and cooling for pools of any size, in both indoor and outdoor applications.

No other heat pump offers the same level of savings and reduced operating costs as our Calorex range. Working at temperatures as low as -10°C, our heat pumps are the ideal pool climate control solution for every type of pool - from private pools and spas, through to hotels and leisure parks.

Benefits of Calorex heat pumps

Take a look at our product spotlights to learn more:

C-PAC+ 6-8-12-15-20 Air source heat pump

Unlike alternative ways of heating your pool, the C-PAC+ requires no fuel storage tank or high capacity electrical supply and produces no smells, fumes or CO2 gases.

I-PAC+ 12-16-22-28 Inverter heat pump

Inverter technology allows for efficient control of the pool temperature, and the I-PAC only uses what energy is needed when it is required. High efficiency with modulating step-less inverter compressor giving an average COP of 10.3.

I-PAC 8-12-16-22 Inverter heat pump

High efficiency with modulating step-less inverter compressor giving an average COP of 9.7.

V-PAC 12-16-22 Inverter heat pump

High efficiency with modulating step-less inverter compressor giving an average COP of 10.7.

I-PAC 50-100BHC Inverter heat pump

High efficiency with modulating step-less inverter compressor giving an average COP of 10.5 (I-PAC 100BHC) and 10.0 (I-PAC 50BHC).

I-PAC 50-100BLY Inverter heat pump

High efficiency with modulating step-less inverter compressor giving an average COP of 10.5 (I-PAC 50BLY) and 10 (I-PAC 100BLY).

Which Calorex heat pump is right for my pool?

How do I calculate what size heat pump I need for a pool?

While many guides and online calculators will be able to give you an idea of which sized heat pump to get for your swimming pool, the best thing you can do is contact an expert.

A heat pump is a significant investment and you need to make sure the one you purchase will give you the biggest returns and efficiency.

Speak to our team today or fill out the form below.

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