Heat pump water heater

A reader wants to know what type of water heater works best in a home with no solar access.

Question
Our hot water system just broke and we are looking for an energy efficient replacement. Do you have any recommendations? It gets quite a lot of use and we have no solar access.
– Don A

Answer

With no solar access, you can’t use a solar water heater as they need long hours of direct sunlight to be effective.

The next most efficient option would be a high quality heat pump water heater such as the Sanden heat pump, which uses CO2 as a refrigerant and has a rated coefficient of performance of around 4, meaning it uses only a quarter of the electricity to heat the water that an electric water heater using resistive elements would use.

Another alternative is an instantaneous water heater as it will supply unlimited hot water – ideal where hot water use is heavy. There are a number of high efficiency units available including models from Rinnai, Bosch and Aquamax, among others. Just select the unit with the appropriate flow rating, bearing in mind that these types of heaters also have a minimum flow rating that they need before they will switch on.

Bear in mind that for situations where hot water is used in short bursts, an instantaneous unit may not be the best option as they are less efficient under such use and there is excessive wear and tear on their valves and control flow switches. In that case, I would go with a heat pump system as it has a storage system.

– Lance

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Cover of Issue 24
You can read more about Heat pump water heater in Issue 24 of Sanctuary magazine.

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Sanctuary: modern green homes is Australia’s premier magazine dedicated to sustainable home design. More...

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Many greywater systems are low-cost, easy to use and can feed your garden with a regular supply of water.

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