How a pool heat pump works
A heat pump does not make heat by burning something or running an element. It moves heat from the surrounding air into the pool water, the same way an air-conditioner moves heat out of a room, just in reverse. A fan draws air across an evaporator, a compressor concentrates that heat, and a heat exchanger passes it into the pool water pumped through the unit.
Because it moves heat rather than making it, a heat pump delivers several units of heat for each unit of electricity it uses. That ratio is the coefficient of performance, or COP, and it is the most important number on the specification sheet. The COP is highest when the air is warm and falls as the air gets colder, which is why a heat pump that performs beautifully in March has to work much harder on a frosty July morning.
Inverter heat pumps vary their compressor and fan speed to match demand, rather than switching fully on and off. They run more quietly and more efficiently once the pool is up to temperature, and they are what we generally recommend.
Sizing: why bigger is not always better, and smaller is worse
Sizing starts with the volume of water. Pools in Centurion and Pretoria commonly hold between 30,000 and 60,000 litres. From there we look at the things that decide how fast the pool loses heat: the surface area, whether it is in full sun or shade, how exposed it is to wind, and — most of all — whether it will be covered at night.
Then there is what you want: a few extra weeks either side of summer, a comfortable pool from September to May, or year-round swimming. Each step up needs more heating capacity, and year-round swimming on the Highveld is a much bigger ask than extending the season.
An undersized heat pump runs constantly, never quite reaches temperature on cold days, and costs more to run than a correctly sized one would. An oversized one costs more to buy than you needed to spend. We size to your pool and your goal, and tell you plainly if the goal is not realistic without a cover.
- Pool volume in litres and surface area
- Sun, shade and wind exposure
- Whether a cover will be used every night
- The target temperature and which months you want to swim
- Where the unit can stand, with airflow and space around it
What drives the running cost
We do not publish a monthly running cost, because it would be wrong for most people who read it. What we can tell you is what makes it go up or down, so you can judge it for your own situation.
- Your electricity tariff, including time-of-use rates if your municipality or Eskom charges them
- The difference between air temperature and your target water temperature
- Whether the pool is covered overnight — the single biggest factor you control
- Wind across the surface, which strips heat away
- How many months of the year you run it
- The COP of the unit at the air temperatures you run it in
Use a cover, or accept a much bigger bill
Most heat is lost from a pool's surface, and most of that loss happens at night when the air is coldest. Heating an uncovered pool on the Highveld is like heating a house with the windows open. A solar blanket on a roller is inexpensive compared with the heat pump itself, and it changes both the size of unit you need and what it costs to run.
If you are not willing to cover the pool, tell us. We will size for that honestly — it just means a larger unit and a higher running cost, and we would rather you knew before you bought.
Installation, electrics and load-shedding
A heat pump is plumbed into the return line after the filter, so it receives clean water, and before a salt chlorinator or chemical feeder, so concentrated chlorine does not pass through the heat exchanger. It needs to stand on a level base with clear airflow around it, and not so close to a bedroom window that the fan becomes a nuisance.
It also needs its own correctly rated electrical supply. That electrical work must be done by a qualified electrician, who can issue the certificate of compliance. We will tell you what the unit requires so your electrician can prepare the supply before we plumb it in.
Heat pumps run off the grid, so load-shedding pauses heating. Plan run times with your area's schedule in mind, and let the pool pump and heat pump restart cleanly after an outage. A heat pump that runs during the warmest part of the day also works at a better COP.
Buying online and booking the install
Heat pumps are in the Heating department of our online shop, alongside solar heating. You pay through PayFast, including Instant EFT, and the heat pump installation is booked as its own item once your payment has cleared, at a time that suits you and our install team. The online shop minimum order is R3,000, which a heat pump clears on its own. Delivery is charged by road distance from our Centurion office.
If you are unsure which unit to choose, send us your pool dimensions, a photo of where the heat pump would stand, and what season you want to swim in. Quoting a new heat pump or installation costs nothing.
How it works
Send your pool details
WhatsApp 081 577 5051 with the pool size, a photo of the equipment area and when you want to swim.
Sizing and quote
We recommend a unit for your pool and your goal, and quote the installation in writing.
Order and pay
Buy the heat pump and installation online through PayFast.
Prepare the supply
Your electrician prepares the dedicated circuit to the unit's requirements.
Install and commission
We plumb it in, set it up and show you how to run it efficiently.
Frequently asked questions
What size heat pump do I need for my pool?
It depends on the pool's litres and surface area, sun and wind exposure, whether you will cover it at night, and which months you want to swim. Send us those details and we will recommend a size.
How much does it cost to run a pool heat pump?
It depends on your electricity tariff, target temperature, air temperature, cover use and months of use. We do not quote a generic figure because it would be wrong for most pools.
Can a heat pump heat my pool in winter?
Yes, but it works harder in cold air, so year-round heating needs a larger unit and a cover every night. Extending the season either side of summer is much easier.
Do I need a pool cover with a heat pump?
Strongly recommended. Most heat is lost from the surface overnight. A cover reduces the size of unit you need and the cost of running it.
How long does a heat pump take to warm the pool?
The first heat-up from cold takes the longest, often a few days depending on size and weather. After that it maintains temperature, especially with a cover.
Is a heat pump better than solar heating?
Solar costs nothing to run but depends on sunshine and roof space, and does little on cold, overcast days. A heat pump heats when you want it to. Some pools use both.
Does load-shedding affect a heat pump?
Yes, it stops while the power is off. Plan run times around your schedule and heat during the warmer part of the day, when the unit works most efficiently.