Heat pump hot water systems: the smart choice for WA homes
Why heat pump hot water systems are becoming the go-to choice for Perth homeowners. Compare brands, costs, and savings. Plus government rebates explained.
Hot water is one of the biggest single loads on an Australian home's energy use, commonly 15–30% of the total. Swap an electric storage tank for a heat pump and you'll typically cut that share by 65–75%, because a heat pump moves warmth already sitting in the outside air into your tank instead of generating heat from scratch. Perth makes this an easy call: winters here rarely dip below 5°C, mild enough that the outdoor unit has warm air to draw on for most of the year. Efficiency does ease off in cold conditions for some refrigerant types, though the CO2 systems covered further down are rated to keep working well past that.
This guide covers how the technology works, which brands suit WA households, what a heat pump actually costs to buy and run, and how much further you can push the savings by pairing one with solar.
What is a heat pump hot water system?
A heat pump works like a fridge running in reverse. A fridge pumps heat out of the cabinet; a heat pump pulls heat in from the surrounding air and moves it into your water tank.
How it works
- Fan draws in air from outside
- Refrigerant absorbs heat from the air
- Compressor intensifies the heat
- Heat transfers to the water tank
- Cycle repeats until the water reaches temperature
The efficiency advantage
Heat pumps are rated by their Coefficient of Performance (COP), which shows how much heat you get out for the electricity you put in:
| System type | COP | What it means |
|---|---|---|
| Electric element | 1.0 | 1 kWh electricity = 1 kWh heat |
| Heat pump (standard refrigerant, typical) | 3.0–4.5 | 1 kWh electricity = 3–4.5 kWh heat |
| Heat pump (CO2 refrigerant) | up to ~6.0 | 1 kWh electricity = up to ~6 kWh heat |
In plain terms, a heat pump uses 65–75% less electricity than a standard electric element to heat the same water. Standard-refrigerant models sit in the 3.0–4.5 band; the CO2 models covered later in this guide push well past that, some close to 6.0.
Why does Perth suit heat pumps so well?
Heat pumps thrive in mild, moderate climates, and that's exactly what Perth offers:
- Average temperature: around 18°C, right in the ideal operating range
- Mild winters: rarely below 5°C, comfortably within the range most heat pumps handle well
- Warm summers: plenty of ambient heat to draw on
- Low humidity: easier on the outdoor unit over its life
Does performance change with the seasons?
Yes, a little. Heat pumps draw more heat from warmer air, so efficiency is typically highest over summer and autumn and eases off through winter. The exact numbers vary by model and refrigerant type, so check the energy-rating label on the unit you're comparing rather than assuming a fixed seasonal curve.
Which heat pump brands are available in WA?
Reclaim Energy's CO2 system
Australian-made, with efficiency at the top of the field:
- Type: CO2 refrigerant
- COP: up to 5.1
- Tank sizes: 270L, 315L
- Warranty: 7 years parts and labour on the compressor, extending to 10 years on the Wi-Fi-connected model, plus a separate 10 to 15 year warranty on the tank depending on tank type
- Price: $3,800–4,500 installed
- Best for: lowest running costs and highest efficiency
Sanden's Eco Plus range
Japanese build quality, also using CO2 technology:
- Type: CO2 refrigerant
- COP: up to 5.96
- Tank sizes: 160L, 250L, 300L, 315L
- Warranty: 6 years on the heat pump unit as standard, extending to 10 years if the system is sold with the Wi-Fi controller package, plus 15 years pro-rata on the tank
- Price: sits in a similar bracket to Reclaim's CO2 system; get quotes to compare exactly
- Best for: smaller households that want a quiet, efficient unit
iStore
A popular all-in-one system:
- Type: R134a refrigerant
- COP: up to 4.0
- Tank sizes: 180L, 270L
- Warranty: around 5 years, confirm the exact term with your installer
- Price: $2,900–3,600 installed
- Best for: value, and a straightforward install
Rheem's Ambiheat range
From a hot water brand most Australians already know:
- Type: R290 refrigerant
- COP: up to 4.5
- Tank sizes: 200L, 270L, 325L
- Warranty: tiered, 10 years on the cylinder supply, 3 years on cylinder labour and the sealed system, 1 year on other parts, confirm the exact terms with your installer
- Price: $2,800–3,500 installed
- Best for: sticking with a familiar name
Comparison table
| Brand | COP | Tank sizes | Warranty | Price range |
|---|---|---|---|---|
| Reclaim CO2 | 5.1 | 270–315L | 7yr compressor (10yr Wi-Fi model) / 10–15yr tank | $3,800–4,500 |
| Sanden | 5.96 | 160–315L | 6yr unit (10yr with Wi-Fi package) / 15yr tank | Similar to Reclaim |
| iStore | 4.0 | 180–270L | ~5 years | $2,900–3,600 |
| Rheem | 4.5 | 200–325L | Tiered, 10yr cylinder / 3yr labour | $2,800–3,500 |
Warranty terms and technology change between models within the same range, so confirm the current spec sheet with your installer before you commit. For a closer look at how these brands differ on technology and long-term cost, our heat pump hot water brand comparison breaks each one down side by side.
How much does a heat pump actually save you?
Here's how the running costs stack up for a typical Perth family of four. These are illustrative estimates. Your real number depends on how much hot water you use and the tariff you're on.
How much does each system cost to run each year?
| System type | Daily use | Annual cost |
|---|---|---|
| Electric storage | 8 kWh | $500–800 |
| Gas storage | N/A | $400–700 |
| Heat pump | 2.5 kWh | $200–350 |
| Solar hot water | 1–2 kWh | $100–150 |
How do the total 10-year costs compare?
These figures assume a standard electricity tariff for the electric storage system. An off-peak or controlled-load plan can lower that cost somewhat, but Synergy's dedicated off-peak hot-water plan is no longer available to new customers, so check what your retailer currently offers before assuming a discount applies.
| System | Upfront | Running (10 yr) | Total |
|---|---|---|---|
| Electric | $1,500 | $6,500 | $8,000 |
| Gas | $2,000 | $5,500 | $7,500 |
| Heat pump | $4,000 | $2,750 | $6,750 |
On these illustrative figures, a heat pump comes out roughly $1,250 ahead of electric storage and $750 ahead of gas over a decade.
What rebates can you get for a heat pump?
How much is the STC rebate worth?
Heat pumps qualify for a federal rebate through the small-scale technology certificate (STC) scheme:
- Value: roughly $800–1,200, depending on your zone and the system (STC prices move, so treat this as indicative)
- How it works: the discount comes off at the point of sale
- Eligibility: the unit must be fitted by an accredited installer
Is there a WA state rebate?
Some states, such as Victoria, run their own heat pump rebates. WA doesn't have a state hot water rebate right now. While you plan, it's worth checking:
- Your local council, for any local schemes
- Synergy, for efficiency incentives
- BillWise, for updates as new programs land
A heat pump is usually just one piece of a bigger switch. If you're weighing it alongside solar, a battery, or ditching gas entirely, our guide to whole-home electrification costs and savings runs the numbers across all of it together.
What do you need to know before installing one?
Where should the outdoor unit go?
The heat pump unit needs:
- Airflow: clear space for air to circulate
- Drainage: somewhere for the condensate to go
- Noise: a bit of thought about how close it sits to neighbours
- Access: room to get to it for servicing
How loud is a heat pump?
For context, roughly how a heat pump compares to other everyday sounds:
| Sound | Noise level |
|---|---|
| Whisper | 30 dB |
| Heat pump | 40–50 dB |
| Conversation | 60 dB |
| Busy road | 70 dB |
Most units run in the early morning, when demand is low and the noise bothers no one.
Where can the tank go?
- Outdoor: most common, usually near the laundry or bathroom
- Indoor: some models suit a garage or utility room
- Roof: split systems put the tank away from the unit
How much more can you save by pairing a heat pump with solar?
Pairing a heat pump with rooftop solar stacks the savings.
How do you schedule a heat pump around solar?
Set your heat pump to run during peak solar generation, roughly 10am to 2pm, on the excess solar you'd otherwise export for a few cents. Do that consistently and you're close to free hot water.
If you already have solar and can't decide between a diverter and a heat pump, our solar diverter vs heat pump hot water comparison walks through which suits which household. Still running an electric tank on an overnight timer? Shifting it to solar hours is the fastest free win available before you spend anything on new hardware.
What does that look like in dollars?
As a general guide, actual savings depend on your system size and how much sun you get:
| Setup | Annual hot water cost |
|---|---|
| Heat pump + grid power | $200–350 |
| Heat pump + solar | $50–100 |
| Heat pump + battery | $0–50 |
Common questions
Will it work in Perth winters?
Yes. Perth winters are mild by Australian standards, and most heat pumps keep performing well through them. The CO2 models covered above are rated well below freezing without needing backup heat. Standard refrigerant units may lean on a backup element on the coldest mornings, but that's rare here.
How long do they last?
A quality heat pump lasts 10–15 years with a bit of upkeep:
- An annual check of the anode
- Keeping the outdoor unit clear
- Checking the pressure relief valve
Are they noisy?
Modern units sit around 40–50 dB. Put one away from bedroom windows, run it during the day, and you'll barely notice it.
How much hot water do I need?
As a general guide, tank size scales with household size, though your actual usage may vary:
| Household size | Tank size |
|---|---|
| 1–2 people | 160–180L |
| 3–4 people | 270–300L |
| 5+ people | 315L+ |
Can I replace my existing system?
Yes. A heat pump can replace:
- Electric storage (straightforward)
- Gas storage (may need some electrical work)
- Solar hot water (often reuses the existing spot)
How do you actually make the switch?
Ready to move to a heat pump? Here's the order things usually happen:
- Work out your needs: household size and how you use hot water
- Get quotes: compare at least three installers
- Check rebates: confirm the STC value and any local incentives
- Book the install: most take half a day
- Lower bills from the first cycle
A heat pump on its own cuts your hot water bill. If gas is still running the rest of your home, our full household gas electrification guide covers heating, cooking, and hot water together, and what removing gas altogether tends to save.
Get free quotes from trusted heat pump installers in Perth, or calculate your savings with our free tool.
Last updated: July 2026. Prices and specifications are indicative and subject to change. Always get professional advice and multiple quotes.
Ready to act? Calculate your gas-to-electric savings →: see what a heat pump and full electrification could save your household.
Money-relevant figures in this article are checked against primary sources. Here’s how we check our facts.
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