Heat Pump Hot Water Systems for Australian Homes

Heat Pump Hot Water Systems for Australian Homes

Heating water is one of the biggest energy costs in many Australian homes. In Victoria, hot water makes up around 18 per cent of household energy use. If your old electric storage tank is near the end of its life, the replacement you choose will shape your power bills for years. A heat pump is one of the most efficient electric options you can buy.

This guide explains how heat pump hot water systems work and what to think about before you buy. It covers sizing, noise, placement, cold weather and running a heat pump from rooftop solar. It also looks at the small scale technology certificates that can lower the upfront price. Rules and incentives differ between states, so check what applies where you live.

How a heat pump hot water system works

A heat pump does not heat water directly with an element the way a standard electric tank does. Instead it draws heat from the surrounding air and moves that heat into the water. The system pairs a heat pump unit with an insulated storage tank. The principle is similar to a reverse cycle air conditioner or a fridge working in reverse.

There are two main styles. In an integrated system the heat pump sits on top of the tank as one unit. In a split system the heat pump is a separate outdoor unit connected to the tank. Split systems can give you more freedom over where each part goes.

The Victorian Government buyers guide says heat pumps use around 60 to 75 per cent less electricity than a conventional electric hot water system. That is a big saving on a cost you pay every day of the year. Heat pumps can heat water at any time of day. Some models are more powerful and reheat the tank faster than others.

Choosing the right tank size

Getting the size right matters. A tank that is too small will run out at busy times, while one that is too large wastes energy keeping water hot. The Victorian hot water buyers guide gives a starting point based on the number of bedrooms. It also suggests you think about how many people may live in the home over the 10 to 15 year life of the system.

• One or two bedrooms: 150 to 225 litres
• Three bedrooms: 225 to 300 litres
• Four or more bedrooms: more than 300 litres

Bedroom numbers are only a guide. Long or back to back showers, regular baths, spas and plumbed washing machines or dishwashers all add to demand. Before buying a bigger tank, it may be worth replacing inefficient showerheads or old appliances first. The guide recommends that sizing is done by a fully qualified technician.

Noise and where to put it

A heat pump has a fan and compressor, so it makes some noise while it runs. The Victorian guide compares the sound to an air conditioner, and levels vary between models. For that reason it should generally not sit close to bedrooms. Think about your neighbours’ windows too.

A spot outside the kitchen or bathroom often works well. Keeping the unit close to where you use hot water also cuts heat loss from long pipe runs. If you are already planning outdoor work, the same thinking about materials applies. If a new fence or screen is part of the same job, our guide to sourcing materials for a sustainable fence can help.

Cold climates and booster elements

Because a heat pump takes heat from the air, it works harder when the air is cold. The Victorian guide notes that colder climates mean more energy and more time to heat water. Efficiency drops and the risk of running out of hot water goes up. This is worth thinking about in alpine areas, Tasmania and inland towns with frosty winters.

Some models have an electric booster element that speeds up heating and helps in cold weather. The catch is that the booster uses more energy and raises running costs. Some models lean on the booster heavily in winter, while others manage well without it. If you live somewhere cold, compare how each model performs at low temperatures before you choose.

Frost is another risk. Some systems include frost protection features. All hot water pipes should be insulated to reduce heat loss and frost damage. This is a cheap job that pays off whatever system you have.

Running a heat pump from rooftop solar

Many heat pumps come with a timer. You can set it to heat water during off peak tariff periods or in the middle of the day when your solar panels are producing. This turns spare daytime solar into stored hot water for the evening. It is one of the simplest ways to use more of your own power at home.

There is a trade off. If the system only heats at set times, you may need a larger tank so you do not run out between cycles. Some smart models can talk to a solar PV system and use solar power more effectively. Ask the installer how the timer settings will suit your household routine.

Pairing efficient hot water with other green upgrades makes the most of the effort. Low impact finishes are an easy next step, and our article on eco friendly paint options is a good place to start. Outdoors, landscaping to boost your green credentials can help shade and cool the house.

Rebates and small scale technology certificates

Eligible heat pumps can create small scale technology certificates under the national Small-scale Renewable Energy Scheme. The Clean Energy Regulator says the model must be on its register to qualify. Air source heat pumps must also be smaller than 425 litres. The system must meet the installer licensing rules set by your state or territory.

Most people do not claim the certificates themselves. Instead they assign the right to a registered agent, who offers a discount on the system in return. This is usually built into the purchase contract, so ask your retailer whether it is included. The Clean Energy Regulator does not set the price agents pay for certificates.

If you do create your own certificates, you need to do so within 12 months of installation. Some states run their own programs on top of the national scheme. In Victoria, for example, only products that meet Victorian Energy Upgrades requirements can be installed under that program. Check your state energy department for what is on offer where you live.

Installation and warranties

Swapping a hot water system involves plumbing and electrical work. Your state or territory sets the licensing rules for who can do it. Warranties vary between manufacturers. Some are only valid if a qualified person installs the system, so keep your paperwork.

A new heat pump is often part of a broader home upgrade. If the installer needs a level base or access path, plan it with the rest of your outdoor work. Our guide to low maintenance decking for Perth heat covers materials that cope with harsh sun. Leave enough clear space around the unit for airflow and servicing.

Frequently asked questions

How much less electricity does a heat pump use?

The Victorian Government guide says around 60 to 75 per cent less than a conventional electric hot water system. Actual savings depend on the model, your climate and how much hot water you use. Your tariff also makes a difference.

Are heat pumps noisy?

They make a noise similar to an air conditioner, and levels vary between models. Try to avoid placing the unit near bedrooms. A wall outside a kitchen or bathroom is often a better choice.

Do heat pumps work in cold weather?

Yes, but they take longer and use more energy when the air is cold. Some models rely on an electric booster in winter, which adds to running costs. Compare cold weather performance if you live in a cool area.

Who claims the small scale technology certificates?

Most owners assign them to a registered agent in return for a discount on the price. You can claim them yourself within 12 months of installation if you have not assigned them. The model must be on the Clean Energy Regulator register.