How to Prepare Your Swimming Pool Heat Pump for Winter

Choosing the right swimming pool heat pump can make a huge difference to how effectively and efficiently you heat your pool.

But with different outputs, inverter technologies, operating temperatures and recommended pool sizes to compare, how do you know which pool heat pump is right for you?

The answer isn’t simply to choose a heat pump based on your pool volume.

Your pool size is an important starting point, but you should also consider when you want to swim, your target water temperature, whether you use a pool cover, the location of your pool and the UK climate.

At HeatPumps4Pools, we specialise in swimming pool heating and help customers choose heat pumps based on their individual pools and heating requirements.

In this guide, we’ll explain the main factors to consider when choosing a pool heat pump and look at some of the different options available.

How Do I Choose the Right Pool Heat Pump?

To choose the right pool heat pump, you need to consider:

• Pool volume
• Pool surface area
• Desired swimming season
• Target water temperature
• Whether the pool is covered
• Pool location and exposure
• Ambient air temperatures
• Available electrical supply
• Heat pump installation location

Looking at these factors together gives you a much better indication of the heating requirement than simply looking at pool volume.

Why Is Correct Pool Heat Pump Sizing Important?

Correct sizing is one of the most important parts of choosing a swimming pool heat pump.

An undersized heat pump might be able to maintain your desired water temperature during warm summer weather but struggle when outdoor temperatures begin to fall.

It may then need to operate for considerably longer to replace the heat being lost from the pool.

However, simply buying the largest heat pump you can afford isn’t necessarily the best solution either.

The aim should be to choose a heat pump appropriately sized for your pool, your swimming season and your desired water temperature.

1. Calculate Your Swimming Pool Volume

Your pool volume is the first figure you’ll need when looking for a heat pump.

For a rectangular swimming pool, you can estimate the volume using:

Length × Width × Average Depth = Pool Volume in m³

For example, an 8m × 4m swimming pool with an average depth of 1.5m would contain approximately:

8 × 4 × 1.5 = 48m³

However, this doesn’t automatically mean that every 48m³ swimming pool should use the same heat pump.

There are several other factors to consider.

2. Decide How Long You Want Your Swimming Season to Be

One of the most important questions is also one of the simplest:

When do you want to swim?

Someone heating their pool during June, July and August has very different requirements from someone wanting comfortable water from April through to October.

As the ambient air temperature falls, your swimming pool can lose heat more quickly and the performance of a heat pump can also change.

This means a heat pump suitable for summer heating isn’t automatically the right choice for extending your swimming season into the cooler months.

When choosing your heat pump, think about your whole swimming season, rather than just the conditions when you’re purchasing it.

3. Consider the UK Climate

Pool heat pumps work by extracting heat energy from the surrounding air and transferring it into your swimming pool water.

That makes ambient air temperature an important consideration.

UK temperatures can vary considerably between spring, summer and autumn, so sizing recommendations intended for consistently warmer climates aren’t necessarily suitable for a British swimming pool.

You should also pay attention to the heat pump’s specified operating temperature range.

For example, the Thermotec Edge Inverter Horizontal Heat Pump can operate at ambient temperatures from -15°C to 43°C, making it suitable for operation across a broad range of conditions.

Rather than looking exclusively at maximum heating output, consider how and when you’re actually planning to use your pool.

4. Use a Swimming Pool Cover

A pool cover is one of the most important additions to an efficiently heated swimming pool.

A considerable amount of swimming pool heat can be lost from the surface of the water, particularly through evaporation.

Covering the pool when it isn’t being used helps reduce this heat loss.

This means your heat pump has less lost heat to replace when maintaining your desired water temperature.

Whether your swimming pool is covered should therefore be considered when sizing your heat pump.

5. Understand Pool Heat Pump kW Ratings

You’ll frequently see swimming pool heat pumps described as 10kW, 15kW, 20kW, 30kW and so on.

But it’s important not to compare heat pumps purely by their headline kW figure.

A heat pump’s heating output and efficiency can vary according to operating conditions, including the ambient air and water temperatures.

When comparing different models, check the conditions under which their specifications were measured.

You should also consider factors including:

• COP
• Inverter technology
• Operating temperature range
• Noise levels
• Electrical requirements
• Heating and cooling functionality
• Wi-Fi or smart controls

The highest output figure doesn’t automatically make one heat pump better than another.

It needs to be suitable for the application.

6. Which Pool Heat Pump Should You Choose?

Different pools have different requirements, which is why HeatPumps4Pools offers a wide range of swimming pool heat pumps.

Here are three examples from our Thermotec range and where we might consider using them.

Thermotec Apex – Compact Vertical Inverter Heat Pump

The Thermotec Apex Inverter Vertical Heat Pump is a premium option for domestic swimming pools where performance and a compact installation are important.

Its vertical fan discharge can make it particularly useful in locations where there isn’t sufficient space in front of the unit for a conventional horizontal fan arrangement.

The Apex features a Mitsubishi compressor, inverter technology, heating and cooling functionality and Wi-Fi control through the Smart Life app.

It’s a strong option to consider for domestic installations where you want a compact, modern inverter heat pump.

Thermotec Edge – A Versatile Choice for Domestic Pools

The Thermotec Edge Inverter Horizontal Heat Pump is available across a broad range of outputs, making it suitable for many different domestic swimming pools.

Models range from 10.5kW with 12kW boost to 30kW with 32kW boost, giving you several options depending on the size and heating requirements of your pool.

The Edge also features inverter operation, Wi-Fi connectivity and an operating temperature range of -15°C to 43°C.

For many domestic swimming pool projects, the flexibility of the Edge range makes it a useful starting point when selecting a heat pump.

Thermotec Nova – For Larger Swimming Pools

For larger pools and higher heating requirements, you may need to move into a more powerful range.

The Thermotec Nova range includes the Nova 36, Nova 36T and Nova 41T, with outputs extending to 41kW.

These models use full inverter technology with a Mitsubishi rotary compressor and offer heating, cooling and automatic operating modes alongside built-in Wi-Fi.

The Nova 36 operates on a single-phase electrical supply, while the Nova 36T and Nova 41T are three-phase models.

This makes the Nova particularly relevant when looking at larger residential pools and commercial swimming pool applications.

7. Think About Where Your Heat Pump Will Be Installed

Correct installation is just as important as choosing the right unit.

A pool heat pump needs access to sufficient ambient air to work effectively.

Installing one in an enclosed area or restricting its airflow can compromise performance.

You should consider:

• Manufacturer airflow clearances
• Fan discharge direction
• Distance from the filtration system
• Pipe diameter and pipe runs
• Water flow requirements
• Condensate drainage
• Electrical supply

These requirements vary between models, so always check the manufacturer’s installation instructions.

Vertical and horizontal heat pumps can also suit different installation locations.

For example, a vertical-discharge model such as the Thermotec Apex directs air upwards, whereas a horizontal model such as the Thermotec Edge discharges air from the front.

8. Should I Buy an Inverter Pool Heat Pump?

For many modern swimming pool installations, an inverter heat pump is well worth considering.

Unlike a traditional fixed-speed heat pump that operates at a fixed output, inverter technology allows the heat pump to adjust its operation according to heating demand.

Once the pool approaches its target temperature, the heat pump can reduce its operating speed rather than continually operating at maximum output.

This can help provide quieter and more efficient temperature maintenance under suitable operating conditions.

The Thermotec Apex, Edge and Nova ranges all use inverter technology.

What Size Pool Heat Pump Do I Need?

There isn’t one universal kW-per-m³ calculation that will accurately size every swimming pool.

Two pools containing exactly the same amount of water could have different heating requirements because of their location, surface area, cover, desired temperature and swimming season.

For this reason, we recommend having your heat pump professionally sized rather than choosing solely from a manufacturer’s maximum recommended pool volume.

When sizing a swimming pool heat pump, we consider factors including:

Pool dimensions and volume
Pool construction
Desired swimming season
Target water temperature
Pool cover
Pool location and exposure
Electrical supply
Installation requirements

Get Expert Pool Heat Pump Sizing from HeatPumps4Pools

Choosing a pool heat pump doesn’t need to involve guessing which kW output looks right.

At HeatPumps4Pools, swimming pool heating is what we specialise in.

We can help you understand your heating requirements and identify suitable options based on your pool and how you intend to use it.

That could be a Thermotec Apex for a compact installation, a Thermotec Edge from our versatile range of domestic heat pumps, a Thermotec Nova for a larger pool, or another model from our wider range.

Need help choosing? Contact the HeatPumps4Pools team for free pool heat pump sizing and expert advice.