Is a heat pump hot water system worth it?

A heat pump hot water system is an air conditioner running in reverse: it moves heat from the outside air into the water rather than generating heat directly. That is why it can deliver several units of heat per unit of electricity, where a resistive element delivers one.

Where it works well

• Mild and warm climates, which covers most of the Australian population.
• Households with solar, since running it during the day turns surplus generation into stored hot water.
• Replacing an old electric storage system, which is where the running cost difference is largest.
• Jurisdictions offering an electrification rebate, which several do.

Where it does not

• Cold climates and alpine areas, where efficiency drops and the backup element does more of the work.
• Locations where the noise matters. A heat pump has a compressor and a fan, and putting one under a bedroom window of a neighbouring home causes real problems.
• Households with no daytime load flexibility and no solar, where the saving is smaller.

What to check on a quote

Ask about the noise rating and where the unit will sit, whether the model has a backup element and how often it engages in your climate, and what the warranty covers on the compressor as distinct from the tank. Those three separate a good installation from a cheap one more reliably than the headline efficiency figure.