How much does a pool heat pump cost to run?

How much does a pool heat pump cost to run per hour?

Multiply the heat pump’s electrical input in kilowatts by your electricity rate in dollars per kWh. That is the whole sum. The hard part is the input figure, because the big number on the box is heat output, not what the unit draws.

One maker’s specification sheet for its inverter range publishes the rated input power at 15°C air, the shoulder-season condition people heat in. Its 21 kW model makes 14 kW of heat in 15°C air and draws 0.75–3.04 kW depending on how hard the inverter is working. At full output, at Sydney’s Ausgrid regulated rate of 33.1372c, that is 3.04 × $0.331372 = $1.01 an hour. Throttled right down it is 25c an hour. The table above runs every model in the range from 9 kW to 28 kW.

A second maker’s brochure agrees within a few per cent. Its 22.5 kW-class unit makes 15.0 kW in 15°C air at a coefficient of performance of 5.1 at full output, so it draws about 15.0 ÷ 5.1 = 2.94 kW, 97c an hour at the same rate.

The kW × cents rule: a pool heat pump costs its input kW times your c/kWh per hour, whatever the weather. The same 21 kW unit draws about 3.08 kW at full output in 26°C air (20 kW of heat, taking the low end of its published coefficient of performance range, 6.5, as the full-output figure, as the sheet’s own 15°C numbers do). What changes with the weather is what each dollar buys: about 13.9 kWh of heat per dollar in 15°C air against 19.6 kWh in 26°C air, at the Ausgrid rate.

Per-hour cost for a pool pump is a separate line on the same bill: what a pool pump costs to run has those figures from the federal Energy Rating registry.

What does a heat pump cost per hour in my state, and in the cheap hours?

The rate is the second input, and it moves the answer as much as the size of the unit does. These are the regulated standing rates for 2026–27, including GST, applied to the 21 kW model at full output (3.04 kW). Your own plan may be cheaper; use the c/kWh on your bill if you have it.

On a time-of-use plan the hour of the day decides the price. The regulators’ 2026–27 caps put cheap windows in the middle of the day and dear ones in the evening:

Run it at midday, not at night. On Energex’s regulated time-of-use cap the 21 kW unit costs 21c an hour between 11am and 4pm, $1.06 for the whole five hours at full output, and $1.45 an hour between 4pm and 9pm. Midday is also when the air is warmest, so the heat pump makes the most heat per kWh exactly when each kWh is cheapest. If you have rooftop solar, a kWh the heat pump uses at midday costs you the feed-in tariff you would otherwise have been paid, which varies by retailer.

A timer is what makes this work; whether you need a timer on your pool heater covers the building-code rule.

How many hours a day will my pool heat pump run?

As many as it takes to put back the heat the pool lost. Warming water takes 4,184 joules per kilogram per °C, so a 50,000 litre pool that loses 2°C overnight needs about 116.2 kWh of heat to recover. A unit making 14 kW needs about 8.3 hours to deliver it, which at full output in Sydney is about $8.36 for the day.

That is the same order as the per-day figure on our cost to heat a pool page, which uses a coefficient of performance of 5 rather than this unit’s 4.6 at full output, and gives the per-degree and per-month costs by city. This page does not repeat them.

A cover changes the hours more than anything else. energy.gov.au says bubble covers can cut heat losses from a heated pool by as much as 75%; at that best case the 8.3 hours fall to about 2.1. Pool cover cost and payback has the price of the cover.

Bigger is not dearer per degree. A bigger unit draws more per hour but finishes sooner, so the heat, and the kWh, are about the same. Size is about how fast you get the pool back to temperature; what size heat pump you need works that out by volume, season and city.

What makes a heat pump cost more than the table

• Running it at the dearest time. On the Ausgrid regulated time-of-use cap the 3pm–9pm peak (November–March and June–August) is 60.1966c, two and a half times the 24.0387c at other times.
• Colder air. The cost per hour barely moves, but each hour buys less heat, so the unit runs longer. One maker rates the same unit at 22.5 kW in 27°C air and 15.0 kW in 15°C air.
• No cover. The heat pump only buys back what the pool loses overnight.
• A standing rate when a market offer is cheaper. The figures here are the regulated default offers; many retail plans undercut them.

If you are pricing a heat pump into a new pool or a replacement, ask each installer for the model’s rated input power at 15°C air, not just its heat output, and run the kW × cents rule on your own tariff. Then compare pool quotes on the same specification. What a pool heater costs to buy and install covers the purchase side, and solar vs gas vs heat pump compares the three ways to heat. Listed pool businesses cover Sydney, Brisbane, Melbourne, Adelaide and Perth.

Common questions

Sources

• Heat pump maker’s specification sheet, inverter range: heating capacity and rated input power at air 15°C / water 26°C, 9–28 kW models (manufacturer-published, hosted by a plumbing distributor, read 16 October 2026)
• Heat pump maker’s pool heating brochure: heating capacity and COP at 27°C and 15°C air (manufacturer-published, read 16 October 2026)
• AER: Default market offer prices 2026–27, final determination (Figure 2.1 flat caps; Figure 2.2 and appendix time-of-use caps and windows; GST included)
• Essential Services Commission: Victorian Default Offer 2026–27 price determination (Schedule 1 flat tariffs; Schedule 3 time of use, solar soak 11am–4pm; GST included)
• Synergy: Home Plan A1, electricity charge 33.2621 cents per unit including GST (read 16 October 2026)
• energy.gov.au: Pool pumps (bubble covers cut heat losses from a heated pool by as much as 75%)
• USGS Water Science School: specific heat capacity of water, 4,184 J per kg per °C

General information only, current at 2026-10-16. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.