Pool Heat Pump COP: What the Number Really Means
How to read the efficiency figure on a pool heat pump spec sheet without being sold a number you will never see.
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COP is how many units of heat a pool heat pump puts into your water for every unit of electricity it takes off the meter. A COP of 5 means 5kW of heat for 1kW of power. It stands for Coefficient of Performance, and it is the single reason a heat pump beats every other form of pool heating on running cost.
Here is the part nobody tells you. The big COP number printed on the box is measured on a warm day with the unit barely working. You will almost never see it. The number that matters is further down the spec sheet, and this guide shows you where to look.
What COP actually means
COP is heat out divided by electricity in, measured at one specific set of conditions. A heat pump drawing 2kW of power and delivering 14kW of heat has a COP of 7. Nothing more complicated than that.
The reason the number goes above 1 is that a heat pump does not make heat. It moves it. The fan pulls warm outside air across a refrigerant coil, the compressor squeezes that heat into a smaller, hotter package, and a titanium heat exchanger dumps it into your pool water. The electricity only runs the compressor and the fan. The heat itself is free, and it comes out of your backyard air. Our guide on how a pool heat pump works walks through the full cycle.
Put COP next to the alternatives and the gap is enormous. An electric element has a COP of 1, because every watt of power becomes exactly one watt of heat and no more. A gas heater is worse than 1 once you account for flue losses. A pool heat pump running at a working COP of 5 is doing the same job for a fifth of the energy.
Why the headline COP is always a best case number
The headline COP on a pool heat pump is measured under the two friendliest conditions the manufacturer is allowed to use: a warm ambient air temperature, and the unit running at its lowest output. Change either one and the number falls off a cliff. Both changes happen the moment the unit is installed in a real backyard.
The test conditions are a warm summer day
Almost every headline COP in the pool industry is measured at Air 27 degrees, Water 26 degrees, humidity 80 percent. That is a humid Brisbane afternoon in February. A heat pump has an easy time in those conditions, because there is plenty of heat in the air to move and the water it is heating is already warm.
Manufacturers publish a second set of figures at Air 15 degrees, Water 26 degrees, humidity 70 percent, which is closer to an April or September morning in most of Australia. That is the honest column. On the Guardian Platinum 20kW the headline is a COP of 16.4 at 27 degrees. At 15 degrees the same unit runs a COP of 7.9 down to 5.3. Still excellent. Less than half the poster figure.
The big number is measured at minimum output
On any inverter heat pump the headline COP is taken at the bottom of its output range, not the top. This is the bit that catches people out. An inverter is at its most efficient when it is idling, because the compressor is turning slowly and the heat exchanger has all the time in the world to do its work.
The Guardian Platinum 20kW puts out between 4.2kW and 20.8kW of heat. At 4.2kW it hits COP 16.4. Wind it up to full output and the same machine drops to COP 7.5. Both figures are true, both are on the same spec sheet, and only one of them is on the marketing image. That is also why the whole inverter argument matters so much, which we cover in inverter pool heat pumps explained.
Real COP figures from our range
Here are the published COP figures from the spec sheets of six units we actually sell, showing the headline number beside the honest one. Every figure below is manufacturer rated, current as of August 2026.
Published COP by model
| Model | Heat output | COP at Air 27 degrees | COP at Air 15 degrees |
|---|---|---|---|
| Guardian Platinum 20kW | 4.2 to 20.8kW | 16.4 down to 7.5 | 7.9 down to 5.3 |
| Guardian Lux-V 17kW | up to 17.0kW | up to 14.5 | about 7.0 down to 4.8 |
| Fairland Aqua X Essential 17.1kW | up to 17.1kW | 14.2 down to 6.6 | 7.3 down to 4.7 |
| Guardian Eco Pro 20kW | 3.7 to 20.0kW | 13.8 down to 6.2 | 6.9 down to 4.6 |
| SensaHeat ES 20kW | up to 20.2kW | 10.8 down to 6.2 | not published |
| Midea M Series 20kW | 21.8kW fixed | 5.2 | 3.6 |
Look at the Midea row. One number, because it is a fixed speed machine with one gear. It cannot idle, so it has no flattering low output figure to quote. A COP of 5.2 is a perfectly good result for an on/off unit, and it is still five times better than an electric element. It just cannot play the same marketing game, which is part of why it stays our best value seller and gets its own Midea 20kW page.
Which COP number to compare when you are shopping
Compare the Air 15 degrees column, not the headline. That column tells you how the unit behaves in the shoulder season, which is exactly when you are running it hardest and when your bill is decided. Nobody needs an efficient heat pump in January.
Two other figures are worth hunting for on a spec sheet.
SCOP is a seasonal COP, averaged across a range of conditions rather than measured at one flattering point. It is much closer to what you will really get. The Fairland Aqua X Essential 17.1kW publishes an SCOP of 7.6 against a headline COP of 14.2, and the SCOP is the number to trust.
COP at 50 percent capacity is the other useful one, because half output is roughly where a correctly sized inverter spends most of its life. The Fairland quotes 10.3 at 50 percent. The SensaHeat ES 20kW quotes an average of 9.1 at 50 percent speed. Those are realistic working numbers.
If a listing gives you one COP figure and no conditions at all, treat it as advertising rather than data. Ask for the full performance table before you buy.
What COP is worth in dollars
Every point of COP cuts the electricity for the same heat proportionally, so going from COP 3.6 to COP 7 halves the bill for identical water temperature. That is the whole argument for paying more for a high COP pool heat pump, and it is easy to put real numbers on.
Raising 1,000 litres of water by 1 degree takes 1.16 kilowatt hours of heat. Heating a 40,000 litre pool by 8 degrees therefore needs 371 kilowatt hours of heat, no matter what equipment you use. What changes is how much electricity buys that heat.
Cost to heat a 40,000 litre pool by 8 degrees
| Working COP | Electricity used | Cost at 30c per kWh |
|---|---|---|
| 1.0 (electric element) | 371 kWh | $111 |
| 3.6 (on/off unit, cool morning) | 103 kWh | $31 |
| 5.2 (on/off unit, warm day) | 71 kWh | $21 |
| 7.0 (inverter, shoulder season) | 53 kWh | $16 |
| 10.0 (inverter, warm day, part load) | 37 kWh | $11 |
Electricity at 30 cents per kilowatt hour, current as of August 2026. Assumes no heat loss during the heat up, so real figures run a little higher.
Multiply that difference across a full season of topping the pool back up and the gap between a COP 4 machine and a COP 7 machine is several hundred dollars a year on a typical family pool. Full season figures are in our pool heat pump running costs guide.
Is a high COP worth paying for
A high COP is worth paying for if you swim outside the peak of summer, and much less so if you only heat the pool for eight weeks a year. The premium is real money. The Guardian Platinum 20kW at $6,290 sits about $1,350 above the Guardian Eco Pro 20kW at $4,940, and the Eco Pro is no slouch.
Do the sum on your own usage. A long season on a large uncovered pool can burn through $1,500 a year of electricity, so a third off that pays the premium back inside three years and then keeps paying. A short summer season on a covered plunge pool might spend $200 a year, and no efficiency figure claws back $1,350 out of that.
One thing that beats every COP figure on this page: a pool cover. It stops the evaporation that carries most of your heat away overnight, and it costs a fraction of the step up between models. Buy the cover first. Then buy efficiency with whatever is left.
Prices current as of August 2026, AUD including GST.
Frequently asked questions
What is a good COP for a pool heat pump in Australia?
A good working COP for a pool heat pump in Australia is 5 or better in shoulder season conditions, which usually means a headline COP of 10 or higher on an inverter model. Anything quoting a headline COP under 5 is a fixed speed unit, which is fine for summer use but will cost more to run across a longer season.
What does COP mean on a pool heat pump?
COP means Coefficient of Performance, the ratio of heat delivered to electricity consumed. A pool heat pump with a COP of 6 puts 6kW of heat into the water for every 1kW of electricity it draws. Higher is cheaper to run.
Why is my heat pump COP lower than advertised?
Advertised COP is measured at Air 27 degrees with the unit at minimum output, and your pool almost never meets both conditions at once. Colder air, colder water and higher output all pull the real COP down, typically to somewhere between a third and a half of the headline number on a cool morning.
Is a COP of 16 real?
A COP of 16 is real but only at one narrow operating point: warm air, warm water and the compressor running at its slowest speed. The Guardian Platinum 20kW genuinely measures 16.4 there, and genuinely measures 5.3 on a 15 degree morning at higher output. Both numbers come off the same test.
What is the difference between COP and SCOP?
COP is efficiency at a single test condition, while SCOP is a seasonal average across a range of temperatures and loads. SCOP is the better guide to what you will actually pay, which is why the headline COP is usually about twice the SCOP on the same unit.
Does a bigger heat pump have a better COP?
A bigger heat pump does not have an inherently better COP, but an oversized inverter unit spends more of its life at low output where COP is highest, so it often runs cheaper than a smaller unit working flat out. That is one of the few good arguments for sizing up rather than down.
Want the real numbers for your pool? Ask us
Send us your pool volume, whether it is covered, your postcode and how long a season you want, and we will tell you which model gives you the best working COP for the money. No poster figures, just the performance table.
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Shop all pool and spa heat pumps
Chasing the highest efficiency in the range? Start with the Guardian Platinum 9kW for small pools, or browse the full Heat Pumps collection. Heating a spa instead? The Spanet 9.0kW SV Series runs a COP of 5.21 and plugs straight into a SpaNET controller.
This guide is general information for Australian pool owners and is not a substitute for advice on your specific pool and site. COP figures are manufacturer rated at stated test conditions and real world efficiency varies with climate, water temperature, pool size and how the unit is operated. Pool heat pumps are electrical appliances and must be connected by a licensed electrician. Prices and specifications are current at the date of publication and change without notice.