Heat pump hot water systems: the smart choice for WA homes

Hot water is roughly a quarter of the average Australian household's energy bill. If you're still running an electric storage tank, you're paying about three times what a heat pump would cost to do the same job. Perth's climate is a big part of why heat pumps do so well here. They pull warmth out of the outdoor air, and Perth has plenty of that to spare year-round.

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

1. Fan draws in air from outside
2. Refrigerant absorbs heat from the air
3. Compressor intensifies the heat
4. Heat transfers to the water tank
5. Cycle repeats until the water reaches temperature

The efficiency advantage

Heat pumps are rated by their Coefficient of Performance (COP) — 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 | 3.0–4.5 | 1 kWh electricity = 3–4.5 kWh heat |

In plain terms, a heat pump uses 65–75% less electricity than a standard electric element to heat the same water.

Why Perth suits heat pumps

Heat pumps work best in mild, moderate climates, which is exactly what Perth gives them:

• Average temperature: around 18°C, right in the ideal operating range
• Mild winters: rarely below 5°C, the point where efficiency starts to drop
• Warm summers: plenty of ambient heat to draw on
• Low humidity: easier on the outdoor unit over its life

Performance by season

| Season | Avg temp | Heat pump COP | Efficiency | |--------|----------|---------------|------------| | Summer | 25–35°C | 4.0–4.5 | Excellent | | Autumn | 15–25°C | 3.5–4.0 | Very good | | Winter | 8–18°C | 2.5–3.5 | Good | | Spring | 15–25°C | 3.5–4.0 | Very good |

Popular heat pump brands 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: 5 years parts, 2 years labour
• Price: $4,500–5,500 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 5.0
• Tank sizes: 160L, 250L, 315L
• Warranty: 6 years tank, 3 years compressor
• Price: $4,000–5,000 installed
• 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: 5 years
• Price: $3,000–4,000 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 3.5
• Tank sizes: 270L, 325L
• Warranty: 5 years
• Price: $3,500–4,500 installed
• Best for: sticking with a familiar name

Comparison table

| Brand | COP | Tank sizes | Warranty | Price range | |-------|-----|------------|----------|-------------| | Reclaim CO2 | 5.1 | 270–315L | 5 years | $4,500–5,500 | | Sanden | 5.0 | 160–315L | 6 years | $4,000–5,000 | | iStore | 4.0 | 180–270L | 5 years | $3,000–4,000 | | Rheem | 3.5 | 270–325L | 5 years | $3,500–4,500 |

The financial case

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.

Annual running costs

| System type | Daily use | Annual cost | |-------------|-----------|-------------| | Electric storage (off-peak) | 15 kWh | $730 | | Electric storage (any time) | 15 kWh | $1,750 | | Gas storage | — | $800–1,000 | | Heat pump | 4–5 kWh | $200–350 | | Solar hot water | 1–2 kWh | $100–150 |

10-year cost comparison

| System | Upfront | Running (10 yr) | Total | |--------|---------|----------------|-------| | Electric | $1,500 | $15,000 | $16,500 | | Gas | $2,000 | $9,000 | $11,000 | | Heat pump | $4,000 | $2,500 | $6,500 |

On these illustrative figures, a heat pump comes out roughly $10,000 ahead of electric storage and $4,500 ahead of gas over a decade.

Government rebates and incentives

Small-scale technology certificates (STCs)

Heat pumps qualify for a federal rebate through the 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

Installation considerations

Outdoor unit placement

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

Noise levels

Modern heat pumps are fairly quiet:

| 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.

Tank location options

• 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

Heat pump + solar: maximum savings

Pairing a heat pump with rooftop solar stacks the savings.

Smart scheduling

Set your heat pump to run when the sun is doing the work:

• During peak solar generation (10am–3pm)
• On the excess solar you'd otherwise export for a few cents
• Which gets you close to free hot water

Typical savings

| Setup | Annual hot water cost | |-------|----------------------| | Heat pump + grid power | $250–350 | | 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 heat pumps work well down to about 5°C. On the coldest mornings a unit might lean on a backup element for a while, 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?

| 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)

Making the switch

Ready to move to a heat pump? Here's the order things usually happen:

1. Work out your needs: household size and how you use hot water
2. Get quotes: compare at least three installers
3. Check rebates: confirm the STC value and any local incentives
4. Book the install: most take half a day
5. Lower bills from the first cycle

Get free quotes from trusted heat pump installers in Perth, or calculate your savings with our free tool.

Last updated: March 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.