Hot water
Hot water systems heat water for your home or business. Modern, efficient electric hot water heat pumps use a refrigerant to extract heat from the air and transfer the heat into a water tank. This is the same technology that your fridge uses to suck heat out of your freezer and your reverse cycle air-conditioner uses to heat or cool your home.
Image Julian Meehan
How does it help save money and reduce emissions?
Hot water makes up about a quarter of an average household’s energy costs and is typically the third largest consumer of energy in your household behind cars and heating. You can save significant energy, money, and emissions by installing an efficient hot water system such as a heat pump or solar hot water system.
Heat pump hot water systems are the most efficient hot water systems (they are three to five times more efficient than electric or gas hot water heaters). Most can be configured to heat water during the day to take advantage of solar power or off-peak tariff times. This will reduce the cost of your hot water even further.
If you are already using your reverse cycle air-conditioner for space heating, electrifying your hot water might be the final step in getting off gas completely which will save you the $1/day connection fee.
How do I get it?
Be ready to install an electric hot water system when your gas hot water system stops working.
No-one makes rational decisions when a system stops working leaving you in a cold shower, so do your research now and prepare for your replacement to be an efficient heat pump or solar hot water system.
Some old-school plumbers still prefer to install what they have been installing for the past 30 years as it’s what they know. Heat pump systems are typically more expensive to buy, but their running costs are extremely low.
Heat pump hot water systems may be split systems (a box compressor like your split system air-con and the storage tank) or integrated (where the compressor sits on top of the tank). Both require an electrical outlet (and possibly a dedicated circuit) so, just like your air-conditioning unit, your installer will need to call in an electrician.
Solar Victoria offers a rebate of up to $1,000 on eligible heat pump and hot water systems and there are a growing number of suppliers and installers specialising in heat pump hot water systems.
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FAQs about what do I need to consider when choosing a heat pump hot water system?
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The refrigerant plays a crucial role as it absorbs the heat from the surrounding air and transports it to the water. However, all refrigerants will eventually end up in the environment. Electrify 2515 says “some refrigerants are greenhouse gasses. CO2 (R744) and Propane (R290) refrigerants are good choices for the environment while R410a and R134a are being banned in various regions.”
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The more efficient your system, the less it will cost to run. There are two ways to measure the efficiency of heat pump hot water systems – the Coefficient of Performance (COP) and the Small-scale Technology Certificates (STCs).
The COP measures how efficient a heat pump hot water system is. A higher COP means the heat pump is more efficient. For example, a COP of 4 means you get 4 units of heating or cooling for every 1 unit of electricity used. However, COP ratings vary depending on the model, the ambient temperature, and the type of refrigerant. Plus, some manufacturers provide overly optimistic COP ratings.
A more reliable indicator of efficiency is to look at STCs which are provided by the Australian Government to reduce the cost of installing an efficient heat pump hot water system. The more STCs, the more efficient the system.
STCs are claimed by installers so quotes should show the full price and reduced price once the STCs are applied by the installer.
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The Victorian Government provides a rebate of up to $1,000 on eligible hot water systems through Solar Victoria.
Victorian government incentives
The Victorian Government offers Victorian Energy Efficiency Certificates (VEECs) to encourage energy efficiency activities in residential and non-residential premises. Each certificate represents one tonne of greenhouse gas emissions reduction (CO2-e).
You can claim both STCs and VEECs and as with STCs, your supplier can claim this benefit from the government, and you pay the difference.
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A general rule is to allow around 75 litres of hot water storage capacity per person. It’s a good idea to match the system to the size of your home (i.e. a four bedroom house would need a system that caters for four to five people), allow for guests and consider if you have other uses for hot water. If you are going to run the heat pump off solar, you may want a bit more storage to ride through the night and morning.
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Most systems are integrated with the tank and compressor in one unit, but they can also come as a separate tank and compressor. Systems with separate compressors take up more space but heat water more quickly.
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Noise levels for heat pump hot water systems vary. Noise levels are quoted in decibels (dB). Most are below 50 dBA which is equivalent to a quiet conversation. As most hot water systems are installed outdoors, carefully consider the location and impact of noise, particularly at night for you and your neighbours.
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With hot water heat pumps you get what you pay for. Systems range in price from $1,500 to $6,800. Electrify 2515 says “Typically the more expensive heat pumps are quieter, use less electricity, have better warranties and use more environmentally friendly refrigerants than their cheaper counterparts.”
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In general, stainless-steel tanks will last the longest (10 years), but high chloride water supplies can affect the durability of these tanks. Glass, enamel, and copper are other options which typically have a shorter life (7~10 years). In metropolitan Melbourne, stainless steel is best as we have good, soft water.
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Check what is covered and for how long as they can be complex and vary substantially and there are different warranty periods for labour, tanks, and parts. Many long warranties apply to the tank only.
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Talk to the manufacturer or prospective installer to understand the electrical requirements. Depending on the unit, you may be able to plug into an existing powerpoint, hardwire to an existing power circuit or you might need a new dedicated circuit on your switchboard.
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● Talk to friends and neighbours about their experiences and recommendations.
● Avoid deals that sound too good to be true, offers from unsolicited phone sales or brochures in the mailbox.
● Do your own research to ensure you get a quality system that’s right for you.
● Many tradespeople have standard suppliers they use and so don’t offer a lot of choice. It is often best to choose the make and model you want, and use the manufacturer’s preferred installers.
● Get two or three quotes which show the price to you net of government rebates and incentives.
● Install your system close to where you’ll use most hot water, such as near the kitchen, bathroom, and laundry.
● Ensure plumbing and electrical work is done by qualified contractors and certificates of compliance are provided after installation.