Is a hot water heat pump right for my situation?

If you read about hot water heat pumps on the website of any plumbing company, it goes something like this:

Title: Should you get a hot water heat pump?

Answer: Yes, you should definitely get a hot water heat pump.

The reality is less black and white. In some situations, it’s a blatant no-brainer to get one. In other situations, you might need to weigh up the pros and cons a bit more.

Let’s cover some of these considerations.

This article is part of our series on hot water heat pumps. See all the other articles here.

How old is your existing system?

Your cold shower day is the day your ancient hot water system finally decides to stop working.

Cold shower day

This is a really convenient moment to get a hot water heat pump. 

On the other hand, if your existing system is quite new, it might not be worth upgrading just yet. For some rebates like the Solar Victoria hot water rebate, your existing system needs to be at least 3 years old for you to be eligible. 

And aside from feeling like a waste, newer gas instantaneous systems are reasonably efficient (just not as efficient as a hot water heat pump) and it might not be financially worth it.

What’s your current system?

Many people will have a hot water system that’s not super new but is working just fine.

In this case, it depends on what you have already. Different hot water systems have different running costs.

Type of hot water systems vs running costs.
Data from Sustainability Victoria

If you have an electric storage hot water system, you’ll save a substantial amount of money on energy bills.

However, if you have a gas instantaneous system and you don’t have too many people at home, you probably won’t save too much money.

And honestly, if you have a solar hot water system already that’s working fine, there’s no reason for you to get a hot water heat pump unless you want the greenest possible home. 

Getting off gas

Another strong reason to make the switch is if you have a gas water heater and you’re trying to stop using gas appliances at home. 

Once you have no appliances powered by gas anymore, you can disconnect from the gas network and save a significant amount on the gas supply charge that you no longer need to pay.

Do you have heaps of excess solar energy?

A hot water heat pump uses much less energy than other systems, but that becomes less important if 

  1. you have a massive solar system that’s generating way more electricity than you need, and 
  2. you have an electric hot water system that can use that electricity.

Hot water heat pumps generally only need to run for 2-3 hours a day, which is great for soaking up solar production during the day.

In this case, it doesn’t matter if hot water heat pumps are 4x more efficient if you’re still paying $0. 

However, in most cases, your system may not be big enough, or because your electricity usage is very high. 

Don’t forget that water heating is a significant user of energy. Water heating takes more energy in winter, while solar production is significantly lower in winter (about half as much as in summer). 

So while in theory, solar + any electric hot water system is fine, in practice your solar system doesn’t generate infinite energy.

Where will you install the hot water heat pump?

Hot water heat pumps need to be installed outside in most cases, otherwise it voids the warranty. 

The easiest scenario is if you already have a storage hot water system that’s outside. You know then that you already have space for the water tank, and you’ll probably have wiring ready to go.

Two of the main variables in installation cost are whether you need to relocate your existing hot water system, and how much new wiring you need to connect it to your switchboard. 

Do you need permission?

If you live in a freestanding house, happy days.

If you live in an apartment, hot water is often a shared utility that’s located on the roof. Unless you convince the strata committee to change the entire hot water system for the building, it might not be practical in your situation. 

If you live in a townhouse, and your hot water system is within your unit boundaries, then you’re good to go (provided you have enough space).


Hot water heat pumps can make more noise than other forms of water heaters. 

The cheaper models can be as loud as a dishwasher (50 dB), while the premium models are whisper-quiet (37 dB).

You’ll want to consider where you put your heat pump and try to avoid areas too close to your bedroom or your neighbours.

Keep in mind that your heat pump usually only needs to run for 2-3 hours each day, so it’s not like it will be on all the time. Many models have a timer so you can run it when it doesn’t wake people up. 

Household size

Will you have enough hot water? The answer is almost certainly yes, so we don’t think this is a consideration in most cases. 

Hot water heat pumps come in different tank sizes which cater for households of up to 8. If you really need more hot water, you can install more than one. 


Since heat pumps extract heat that’s already in their air and move it into the water tank, the ambient temperature affects how efficient it is. 

Some products can work well in temperatures as low as -15°C, while others will start struggling when it gets colder than 5°C. 

If you’re in Australia, provided you choose the right product and get it installed correctly, you don’t have anything to worry about. 

Bottom line

Here are some things we find ourselves saying a lot:

  • Have a new-ish electric hot water system and plenty of spare solar generation?
    • Don’t get a hot water heat pump. 
  • Have a new-ish gas instantaneous hot water system with 2 people at home?
    • Don’t get a hot water heat pump if savings are all you care about
  • Trying to get off gas?
    • Get a hot water heat pump.
  • Have an electric water heater and a large family?
    • Get a hot water heat pump.
  • Did your old hot water system finally decide to stop working?
    • Definitely get a hot water heat pump.

Next steps

If you think that a hot water heat pump makes sense for your situation, read about the most important decision you need to make

Or if you want to know whether a hot water heat pump is worth it for your house, get an instant cost, savings and rebates estimate.