Do You Need a Pool Cover With a Heat Pump?
The accessory question we answer on almost every heat pump sale, answered once, properly.
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Yes, you need a pool cover with a heat pump if you care at all about the power bill. A heat pump will run without one, and nothing breaks. But an uncovered pool loses around three times as much heat as a covered one, so the heat pump spends most of its hours replacing warmth that went straight into the night air. On a typical 40,000 litre Australian pool, a cover cuts heat pump running costs by about two thirds.
That is the whole answer. Everything below is the numbers behind it, and which cover to buy.
Why a heat pump without a pool cover struggles
A heat pump without a pool cover struggles because evaporation off the open water surface is the biggest heat loss a pool has, and a heat pump cannot outrun it cheaply. Every litre of water that evaporates carries a large amount of heat away with it. It happens all night, it happens faster in wind, and it happens hardest when the air is cool and dry.
A floating cover stops most of that evaporation dead. Without one, the pool hands most of the day's heating back to the sky by 6am.
People blame the heat pump for this. It is almost never the heat pump.
What a pool cover saves on heat pump running costs
A pool cover saves roughly $120 a month in heat pump running costs on a 40,000 litre pool held at 28 degrees with an inverter heat pump, and closer to $170 a month with an on/off unit. Here is where those figures come from.
Covered vs uncovered, 40,000 litre pool
| Setup | Heat lost per day | Cost per month | Cost over a 6 month season |
|---|---|---|---|
| Covered pool, inverter heat pump | About 55 kWh | About $70 | About $420 |
| Uncovered pool, inverter heat pump | About 150 kWh | About $190 | About $1,140 |
| Covered pool, on/off heat pump | About 55 kWh | About $100 | About $600 |
| Uncovered pool, on/off heat pump | About 150 kWh | About $270 | About $1,620 |
Based on a 40,000 litre pool of about 32 square metres held at 28 degrees in a moderate Australian shoulder season, electricity at 30 cents per kWh. Figures current as of September 2026. Your climate, tariff and set temperature will move them.
Over a six month season the cover is worth $700 to $1,000 in electricity on that pool. Every season. A decent cover costs less than that, which is why we tell people to buy the cover before they spend another cent on kilowatts. The full working is in our pool heat pump running costs guide.
A pool cover lets you buy a smaller heat pump
A covered pool can usually run a heat pump one size smaller than the same pool left open, because the heat pump only has to replace about a third of the heat loss. That is money off the purchase, not just the bill.
Real examples from our range. The Guardian Eco Pro 16kW is $4,401 and the Guardian Eco Pro 20kW is $4,940, a $539 step. The SensaHeat ES 13kW is $3,200 and the SensaHeat ES 16kW is $3,800, a $600 step. On plenty of pools, the cover pays for itself before the heat pump is even switched on.
Prices current as of September 2026, AUD including GST.
One caveat. Only size down if the cover will genuinely go on every night. A cover folded up behind the shed does nothing, and an undersized heat pump on an open pool is the most expensive combination there is. If you are unsure, our pool heat pump sizing guide walks through it by litres.
Which type of pool cover works best with a heat pump
A thermal foam blanket holds the most heat, a bubble blanket is the best value, and a liquid cover is the weakest option but better than nothing. An automatic slatted cover works well mostly because people actually use it. The honest comparison looks like this.
Pool cover types compared
| Cover type | How it keeps heat in | Heat retention | Watch out for |
|---|---|---|---|
| Bubble blanket (solar blanket) | Floating sheet of air bubbles stops evaporation and adds some solar gain in sun | Good | Sun breaks it down over a few seasons; bigger pools need a roller |
| Thermal foam blanket | Closed cell foam stops evaporation and insulates the surface | Best of the floating covers | Heavier and dearer; a roller is close to mandatory |
| Liquid cover | Thin film on the water surface slows evaporation | Weakest | Wind and swimmers break the film; needs regular redosing |
| Automatic slatted cover | Motorised slats seal the surface at the push of a button | Good | Most expensive; easiest to fit during a build or renovation |
General guide only. Performance varies by product, fit and how consistently the cover is used.
Our blunt advice for most backyard pools: a good bubble blanket on a roller. The roller is the difference between a cover that goes on every night and one that stops going on in week three. Get it cut to fit, with no gaps at the edges.
Using a pool cover and a heat pump together
The best routine is to run the heat pump through the warmest part of the day and have the cover on from late afternoon until morning. Heat pumps do their best work when the air is warm, and the cover does its best work overnight when evaporation is worst. The two jobs fit together neatly.
A few practical points we give every customer.
- The filter pump has to run. A pool heat pump only heats while water is flowing through it, so filtration time caps heating time. A variable speed pump such as the Fairland InverPro variable speed pool pump makes long, slow run times cheap.
- Covering the pool during the day is fine. The heat pump heats the water through the plumbing, not the surface, so a cover left on while it runs costs nothing in performance.
- Take the cover fully off before anyone swims. Never swim under or on a floating cover.
- A cover is not a pool barrier. Pool fencing rules still apply in every Australian state, cover or no cover.
- Ask your pool shop about chemicals. Some treatments, especially a heavy shock dose, are best done with the cover off for a while. Follow their advice for your sanitiser.
When a cover matters less
A cover matters least on a summer only pool in a warm, still climate where you only want a few degrees of lift. Tropical Queensland in January, a sheltered courtyard, water that is already sitting at 26 degrees. The heat pump is doing a light top up job and the losses are modest.
Even then it saves money, just less. For anyone heating in shoulder season or winter, a cover is not optional.
Where an inverter heat pump fits in
An inverter heat pump on a covered pool is the cheapest pool heating setup short of solar, because the covered pool loses so little heat that the inverter spends most of its time idling at low power. Low speed running is where inverter units are most efficient, and a cover keeps them there.
The Fairland Aqua X Essential 17.1kW at $4,140 and the Guardian Platinum 20kW inverter at $6,290 are the two we point most covered family pools at. If purchase price matters more than running cost, our best seller is still the Midea M Series 20kW with WiFi at $3,799, and a cover makes a bigger difference to an on/off unit like the Midea than to anything else in the range. Full detail sits on the Midea 20kW page.
Prices current as of September 2026, AUD including GST.
The whole range from 9kW to 35kW is in Heat Pumps for Pools & Spas.
Frequently asked questions
Do I need a pool cover with a heat pump in Australia?
Yes, if you want reasonable running costs. A heat pump works without a cover, but an uncovered pool loses around three times the heat of a covered one through evaporation, so a cover cuts heat pump running costs by about two thirds on a typical 40,000 litre pool.
How much does a pool cover save on heat pump running costs?
On a 40,000 litre pool held at 28 degrees, a cover saves about $120 a month with an inverter heat pump and about $170 a month with an on/off unit, at 30 cents per kWh in a moderate shoulder season. Over a six month season that is roughly $700 to $1,000.
Can I use a solar blanket with a pool heat pump?
Yes, and a solar blanket (bubble blanket) is the best value cover to pair with a pool heat pump. It stops most evaporation overnight and adds a little solar gain during the day. Put it on a roller so it actually gets used every night.
Can I leave the pool cover on while the heat pump is running?
Yes. A pool heat pump heats the water through the filtration plumbing, not through the surface, so a cover left on while the heat pump runs does not reduce heating and keeps more of the heat in.
Can I buy a smaller heat pump if my pool has a cover?
Usually yes, one size down from the uncovered recommendation, because a covered pool loses far less heat. Only do it if the cover will genuinely go on every night, since an undersized heat pump on an uncovered pool is the worst combination for both comfort and running cost.
Should I put a cover over the heat pump unit itself?
Never cover a pool heat pump unit while it is running, because it needs clear airflow across the coil to work. If the unit is switched off for winter, follow the manufacturer's instructions before fitting any cover to the unit.
Not sure what your pool needs? Ask us
Tell us your pool volume, your postcode, whether you have a cover (or plan to) and how long a season you want. We will tell you the heat pump size that fits and what it should cost to run.
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This guide is general information for Australian pool owners and is not advice on your specific pool, site or climate. Running costs shown are illustrative figures based on stated assumptions, not a quote. Pool heat pumps are electrical appliances and must be connected by a licensed electrician. Pool fencing and barrier requirements apply regardless of any cover. Confirm final sizing with us or your pool professional before you buy.