Heat Pump Sizing Guide
A practical guide to sizing an AquaSolis inverter heat pump for your pool.
Choosing the right heat pump size helps your pool reach the temperature you want, maintain it more efficiently, and avoid unnecessary strain on the system.
AquaSolis heat pumps are built for real Australian backyards — hot days, cool evenings, coastal air, changing seasons, and everyday family use. Correct sizing helps the system heat properly, maintain comfort more efficiently, and suit the way the pool is actually used.
Start with How You Want to Use Your Pool
A pool heat pump is one of the most efficient ways to extend your swimming season, but the size of the unit matters. Pool volume is only the starting point. Location, wind exposure, shade, desired temperature, cover use, daily run time, and the months you want to swim all influence the final recommendation.
Because these conditions vary from backyard to backyard, this guide should be used to understand the main sizing factors and narrow the likely size range — not as an exact heat pump calculator.
- Extended season use: ideal for swimming from around September to April
- Warmer comfort swimming: suited to families wanting more consistent water temperature
- Cooler climate use: may require a larger heat pump to maintain temperature
- Spa or swim spa use: may require higher temperature settings and careful sizing
- Uncovered or exposed pools: usually need more heating capacity due to greater heat loss
Sizing tip: choose the heat pump around real use — not just the litres on paper.
Basic Extended Season Sizing Guide
The table below provides a general guide for extending your swimming season from September to April, using a target water temperature of approximately 28°C.
| Location | 20,000L | 40,000L | 60,000L | 80,000L |
|---|---|---|---|---|
| Brisbane | 9–13kW | 9–13kW | 13–17kW | 20–21kW |
| Sydney | 9–13kW | 13kW | 20–21kW | 24–28kW |
| Melbourne | 13kW | 20–21kW | 28kW | 35kW |
| Canberra | 13kW | 20–21kW | 28kW | 35kW |
| Hobart | 13kW | 20–21kW | 28kW | 35kW |
| Adelaide | 13kW | 16–17kW | 24–28kW | 35kW |
| Perth | 9–13kW | 16–17kW | 21–24kW | 28kW |
Please note: This table is a guide only. It assumes an average in-ground pool fitted with a thermal cover, a target water temperature of approximately 28°C, and a daily run time of around 10 hours during the extended swimming season. Actual performance may vary depending on pool volume, wind exposure, shade, soil conditions, time of year, plumbing layout, cover quality, filtration run time, and local weather conditions.
What Changes the Size You Need?
Two pools with the same litre capacity may still need different heat pump sizes. These are the main factors that affect the final recommendation.
Pool Volume
Larger pools need more heating capacity because there is more water to heat and maintain.
Location & Climate
Cooler regions, low night temperatures, and longer shoulder seasons increase heating demand.
Pool Cover
A thermal cover helps retain heat and can significantly reduce daily heat loss.
Wind & Exposure
Open, windy, or exposed pools lose heat faster than sheltered pools.
Desired Temperature
Maintaining 30°C or more requires more energy than maintaining a standard 26–28°C swimming temperature.
Swimming Season
Spring-to-autumn heating is different from year-round use through colder winter conditions.
How to Estimate Your Heat Pump Size
For a quick first estimate, use your pool volume as a starting point. This does not replace a proper sizing assessment, but it helps narrow the range before comparing models.
Calculate your pool volume
For a rectangular pool, multiply length by width by average depth.
Pool Volume in m³ x 1,000 = Pool Volume in Litres
Example: 8m x 4m x 1.5m = 48m³, or approximately 48,000 litres.
Use the simple kW guide
For a quick estimate, divide your pool volume in litres by 2,500.
Example: 48,000L ÷ 2,500 = 19.2kW. In this case, you would generally look toward a 20–21kW heat pump rather than rounding down.
Adjust for your conditions
A simple formula does not include wind, shade, cover use, climate, plumbing distance, target temperature, or the months you want to swim. If your pool is exposed, uncovered, in a cooler region, or you want higher water temperatures, move up in size.
Choose for comfort, not just litres
A correctly sized heat pump should suit how you actually use your pool. A family swimming after school, a homeowner wanting spring-to-autumn comfort, and someone heating a spa or swim spa may all need different recommendations.
Why a Pool Cover Makes Such a Difference
Most pool heat is lost from the water surface, especially through evaporation. A thermal pool cover helps retain heat overnight and when the pool is not in use, meaning the heat pump does not need to work as hard to maintain your preferred temperature.
With a Pool Cover
- Better heat retention overnight
- Lower heating demand
- More stable water temperature
- Reduced evaporation
- Often allows a smaller or more efficient setup
Without a Pool Cover
- More heat lost from the water surface
- Longer run times may be required
- Higher running costs are likely
- Larger heat pump capacity may be needed
- Temperature recovery can take longer
Helpful tip: Using a thermal pool cover can make a noticeable difference. It helps hold warmth, reduce heat loss, and support efficient heat pump operation.
How AquaSolis Inverter Heat Pumps Help
AquaSolis inverter heat pumps are built to maintain comfortable water temperature without unnecessary complexity. Instead of running only at full power, inverter technology can adjust output to suit the heating demand of the pool.
Stable Temperature
Inverter control helps maintain water temperature more steadily once the pool reaches the set point.
Efficient Operation
By modulating compressor and fan speed, the unit can reduce energy use when full output is not required.
Quieter Performance
Lower operating speeds can reduce noise during everyday temperature maintenance.
AquaSolis Heat Pump Range Overview
AquaSolis inverter heat pumps are built in a range of capacities and installation layouts to support different pool sizes, climate conditions, and heating goals. The table below is a general overview only. Current model availability and specifications should be confirmed before purchase.
| Range | Available Sizes | Best Suited For | Key Features |
|---|---|---|---|
| AquaSolis AQS+ | 13kW, 17kW, 21kW, 28kW, 35kW three phase | Premium pool and spa heating with an ultra-quiet back discharge design. | Reverse cycle heating and cooling, Wi-Fi, Mitsubishi twin-rotary DC inverter compressor, R32 refrigerant, and twisted titanium heat exchanger. |
| AquaSolis AQS Series TurboSilence | 13kW, 17kW, 21kW, 26kW, 32kW, 32kW three phase, 40kW three phase | High-efficiency inverter pool heating with Turbo, Smart, and Silence operation modes. | TurboSilence inverter technology, Wi-Fi control, titanium heat exchanger, quiet performance, and extended operating range. |
Model availability may vary. Always confirm current product specifications, electrical requirements, and installation suitability before purchase.
Simple Model Direction by Pool Volume
Use this as a broad starting point only. In cooler climates, uncovered pools, windy locations, or year-round use, the correct recommendation may move up.
| Approx. Pool Volume | Likely AquaSolis Size Range | General Direction |
|---|---|---|
| Up to 30,000L | 13–17kW | Common for smaller family pools, warmer regions, and covered pools. |
| 30,000L–40,000L | 17–21kW | Suitable for many average residential pools depending on location and exposure. |
| 40,000L–60,000L | 21–28kW | Often suited to larger family pools, extended season use, or cooler regions. |
| 60,000L–80,000L | 28–35kW | Generally suited to larger pools, higher heat demand, or southern climates. |
| 80,000L+ | 35kW+ / professional sizing recommended | Larger pools should be assessed carefully, especially for uncovered or year-round heating. |
This table is a simplified selection guide and does not replace a proper heat pump sizing assessment.
Installation Factors That Affect Performance
Even a correctly sized heat pump needs the right installation conditions. Airflow, plumbing position, water flow, and electrical connection all affect performance.
- Outdoor ventilation: AquaSolis heat pumps must be installed in a well-ventilated outdoor location. Poor airflow can reduce performance.
- Plumbing position: The heat pump is generally installed after the pump and filter, and before the chlorinator or sanitiser.
- Water flow: The filtration pump must provide the recommended flow rate for the selected model.
- Pipe length: Shorter pipe runs between the pool and heat pump help reduce heat loss and support efficient operation.
- Qualified installation: Installation and electrical connection must be completed by suitably qualified professionals, with electrical work carried out by a licensed electrician where required.
Safety note: Always follow the product manual and local requirements. Incorrect installation may affect performance and warranty.
Frequently Asked Questions
What size heat pump do I need for my pool?
Start with pool volume, then adjust for climate, cover use, wind exposure, shade, preferred water temperature, and how long you want to swim each year. As a quick guide, divide pool litres by 2,500 to estimate the approximate kW required for extended season heating with a cover.
Should I choose a larger heat pump?
If your pool is exposed, uncovered, in a cooler region, or you want a longer swimming season, choosing the next size up is often more suitable. An undersized heat pump may need to run harder for longer to reach and maintain temperature.
Does a pool cover reduce the heat pump size I need?
A thermal cover reduces heat loss and can reduce heating demand. It does not remove the need for correct sizing, but it can help the heat pump maintain temperature more efficiently.
Can an AquaSolis heat pump cool the pool?
AquaSolis AQS+ models include reverse cycle heating and cooling, which can help manage water temperature through both cooler and warmer parts of the year.
Can I install a pool heat pump myself?
Heat pump installation should be completed by suitably qualified professionals. Electrical work must be carried out by a licensed electrician or suitably qualified person in line with the product manual and local requirements.
What is COP on a pool heat pump?
COP stands for Coefficient of Performance. It measures how efficiently a heat pump uses electricity to transfer heat into the pool water. For example, a COP of 5 means the heat pump can produce around 5kW of heat output for every 1kW of electricity used under the stated test conditions.
A higher COP generally means more efficient operation, but COP can change depending on air temperature, water temperature, humidity, operating mode, and installation conditions.
COP is useful when comparing efficiency, but it should not be used on its own to choose a heat pump size. For sizing, start with pool volume, location, cover use, desired temperature, swimming season, and how the pool is actually used.
Important sizing information. This guide provides general information only. Heat pump sizing depends on many variables, including pool volume, location, wind exposure, shade, plumbing layout, filtration run time, desired temperature, pool cover quality, time of year, and installation conditions.
For the most suitable recommendation, submit your pool details through our The Right Heat Pump form or speak with a qualified pool professional before purchase.
