Heat pump hot water in Perth: cost, rebates, running costs and brands

A heat pump hot water system is usually the cheapest way to heat water in a Perth home on Synergy electricity. It moves heat from the outside air into the tank instead of making heat with an element, so it uses roughly a third to a fifth of the electricity an electric storage tank needs for the same hot water. It costs more to buy than a like-for-like electric or gas tank. Federal small-scale technology certificates (STCs) take part of that price off at the point of sale. Running it in the middle of the day, on your own solar or in Synergy's Midday Saver window, cuts the running cost further.

COP (coefficient of performance): how many kWh of heat a system delivers for each kWh of electricity it uses. A heat pump running at a COP of 4 turns 1 kWh of electricity into 4 kWh of heat. An electric element is always 1 to 1.

Hot water is one of the largest loads in most Perth homes, often the biggest after air conditioning, and unlike air conditioning it runs all year. This guide covers what drives the price, how the rebate works, what a heat pump costs to run on Synergy's plans, and how to choose a system and brand.

How does a heat pump hot water system work?

A heat pump works like a fridge in reverse. A fan draws outside air across a refrigerant, which absorbs its heat. A compressor concentrates that heat, and it transfers into the water in the tank. The cycle repeats until the water reaches temperature.

Because it moves heat rather than generating it, a heat pump delivers about three to five kWh of heat for every kWh of electricity, depending on the model and the air temperature on the day. Standard-refrigerant models sit toward the lower end of that range; CO₂ models sit toward the top.

Perth suits the technology well. Winters are mild and summers are warm, so there is usable heat in the air for almost the whole year. Output eases a little on cold mornings, which is another reason to run the timer in the middle of the day.

What does a heat pump hot water system cost in Perth?

The installed price varies more than most people expect, so compare two or three itemised quotes rather than a headline figure. What drives the price:

1. Tank size. Bigger households need a bigger tank, and the tank is a large part of the cost.
2. Refrigerant and design. CO₂ systems and split systems, where the heat pump sits apart from the tank, generally cost more upfront than integrated all-in-one units.
3. What you're replacing. Swapping out an electric storage tank is usually straightforward. Replacing a gas system means a plumber caps the gas line and an electrician may need to run a new circuit, and both trades add labour to the job.
4. Where it goes. Tight access, a new location, or extra plumbing runs add time.
5. Removal and disposal of the old system.
6. The STC discount, covered below, which comes off the quoted price.

Ask each installer to break the quote into the unit, installation, any gas or electrical work, and the STC discount, so you're comparing like with like.

What rebates are there for heat pump hot water in WA?

The rebate pathway is the federal Small-scale Renewable Energy Scheme, run by the Clean Energy Regulator (CER). Eligible heat pump hot water systems earn small-scale technology certificates (STCs) when they're installed.

• How much: the number of certificates depends on the model and the climate zone you live in, and what each certificate is worth moves with the certificate market. That's why the dollar figure differs from quote to quote.
• How you get it: most installers take the certificates and discount your price at the point of sale, so you don't claim anything yourself. Check that the discount appears as its own line on the quote.
• Eligibility: the model has to be an eligible system and installed to the scheme's requirements. Your installer confirms this for the unit they're quoting.

The CER explains how the certificates work on its small-scale technology certificates page. Some other states run their own hot water programs on top of the federal scheme. Ask your installer whether anything else applies in WA at the time you buy.

What does a heat pump cost to run on Synergy plans?

Every kWh of electricity a heat pump uses delivers several kWh of hot water, so whatever rate you pay, it goes three to five times further than it does in an electric element. How much you pay per kWh depends on your plan and when the heat pump runs.

On the A1 flat rate. You pay 33.26c/kWh whenever the heat pump runs. The heat pump's advantage over an electric storage tank is purely the COP: the same hot water for a fraction of the electricity.

On Midday Saver. Synergy's Midday Saver plan charges 8.85c/kWh in the super off-peak window from 9am to 3pm. Set the heat pump's timer inside that window and each kWh of hot water costs a small fraction of what an element on the A1 rate costs. The plan's other bands cost more, so the timer matters. Our Midday Saver vs A1 comparison covers when the plan suits a household overall.

With rooftop solar. Midday solar your home doesn't use is exported under DEBS, at 2c/kWh outside the 3pm to 9pm peak. Run the heat pump from that surplus instead and each kWh you use yourself is worth the rate you'd otherwise pay for grid power, rather than the small export credit. On a sunny day, a heat pump timed to the middle of the day can heat most or all of the tank from your own panels.

Compared with gas. Running cost against gas depends on your gas retailer and plan. WA gas retail is competitive, so compare current gas plans before you weigh a switch.

When should you run a heat pump?

In the middle of the day. Most heat pumps have a built-in timer. Setting it to run from late morning to early afternoon lines it up with your solar generation, the Midday Saver super off-peak window, and the warmest air of the day, when the heat pump is most efficient. Some systems carry a backup element that tops up on high-demand days, so check it isn't doing more of the work than it should. Our guide to timing your hot water around solar walks through the settings.

Should you get a heat pump or a solar diverter?

If you already have solar and an electric storage tank in good condition, a solar diverter is a cheaper alternative: it sends surplus solar into your existing element instead of replacing the system. A heat pump uses far less electricity per litre of hot water and works on a timer regardless of the weather, which makes it the stronger fit when the old tank is due for replacement or you're moving off gas. Our solar diverter vs heat pump comparison covers which suits which household. For roof-mounted collectors, see solar thermal vs heat pump hot water.

How do you choose a heat pump for a Perth home?

1. Tank size. As a rough starting point, one or two people usually suit a tank around 160–180L, three or four people 270–300L, and five or more 315L or larger. Back-to-back morning showers call for more buffer, so check the manufacturer's sizing guide against your household.
2. Refrigerant. CO₂ models hold their efficiency better in cold air and heat water to high temperatures efficiently. Perth's mild winters narrow that advantage compared with colder cities, but it doesn't disappear.
3. Integrated or split. Integrated units put the heat pump on top of the tank in one piece and need clearance above and around them for airflow. Split systems separate the outdoor heat pump from the tank, which helps where outdoor space is tight or you'd like the tank inside.
4. Noise. Most units run at about the level of quiet conversation, similar to a small air conditioner's outdoor unit. Keep them away from bedroom windows and neighbours' windows, and check your council's rules on residential equipment noise.
5. Location. A heat pump draws heat from the surrounding air, so it needs ventilation and somewhere for condensate to drain. Don't put it in a sealed space.
6. Warranty. Compare the heat pump unit's warranty and the tank's warranty separately, and confirm the terms that apply in WA for the exact model on your quote.
7. Local service. A brand with plenty of Perth technicians is easier to get serviced over a 10 to 15 year life. Some systems need specialist installation knowledge, so check your installer regularly works on the brand they're quoting.

Which heat pump brands are sold in Perth?

Several brands cover most of the Perth market. None is the right answer for every home; they differ on refrigerant, design, tank options, and service network.

Model ranges, efficiency ratings and warranty terms change, so check the current spec sheet for the exact model on your quote rather than relying on a brand's headline figures.

Should heat pump hot water be your first electrification step?

For many households it's the first one. It's a single appliance change that moves one of the biggest loads in the house onto the most efficient technology available, and it runs happily on midday solar. If gas is still running the rest of your home, our household gas electrification guide covers heating, cooking and hot water together, and whole-home electrification costs runs the numbers across all of it. A common next step is switching from a gas cooktop to induction. For the bigger picture, see the electrify everything movement.

Check the numbers for your home

Your saving depends on what you're replacing, how much hot water your household uses, and when the system runs. The BillWise upgrade calculator takes your current hot water type and estimates what a heat pump would save you. Our heat pump page compares hot water with heating and cooling upgrades. When you're ready to compare prices, get matched with Perth installers for quotes.

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Costs, rebate values and product specifications change. Get itemised quotes from licensed plumbers and electricians for your property, and ask your installer to confirm the STC discount and any other program that applies at the time you buy.