Are Hot Water Heat Pumps Worth It?
Here’s something most people don’t realise until they see their power bill broken down: heating your water is costing you a lot more than you think.
On average, domestic hot water heating accounts for around 28% of a typical New Zealand household power bill. That’s more than a quarter of what you’re spending on electricity - just to keep the water hot. So when customers ask me whether a hot water heat pump is worth it, my answer is almost always yes. But let me explain why, so you can make the call for yourself.
What is a hot water heat pump, exactly?
A hot water heat pump works on the same principle as the heat pump heating your living room - it pulls warmth from the outside air and uses it to heat something else. In this case, instead of warming your home, it’s heating your water cylinder.
It doesn’t generate heat from scratch, which is why it’s so much more efficient than a traditional electric element or gas system. For every 1kW of electricity it uses, a well-designed hot water heat pump can deliver around 3.6kW of heat output. That efficiency is measured as COP - Coefficient of Performance - and a COP of 3.6 compared to a traditional electric element at close to 1.0 tells you everything you need to know.
How much could you actually save?
The system we install here at The Heat Pump Shop is the Black Diamond AquaCore - a New Zealand-designed and manufactured hot water heat pump that can save up to 80% on your hot water heating costs compared to a standard electric or gas system.
For a typical South Canterbury household running a direct electric hot water cylinder, that’s a meaningful saving every single month. The system also has a fast recovery time - it can reheat a full 180-litre cylinder in around 2.5 hours, compared to over 3 hours for a traditional electric cylinder in winter conditions.
Does it work in winter? What about cold South Canterbury temperatures?
This is the question I get asked most often, especially from people in inland areas like Fairlie, Twizel, or Geraldine where temperatures can get properly cold.
The AquaCore is designed to operate from -15°C to +45°C ambient temperature. So yes - it works through a South Canterbury winter without any issues. It’s specifically built for New Zealand conditions.
What does installation involve?
The good news is that if you already have a hot water cylinder, the AquaCore is designed to retrofit onto it. You don’t necessarily need to replace your existing cylinder, which keeps installation costs down.
The system has two main components - an outdoor unit (similar in size to a standard heat pump outdoor unit) and an indoor heat exchanger that connects to your cylinder. It also comes Wi-Fi enabled, so you can control the water temperature and set heating schedules via an app - timing your heating around off-peak power rates, or making sure hot water is ready when you actually need it rather than running 24/7.
Is it the right choice for your home?
A hot water heat pump makes the most sense if:
• You’re on a direct electric hot water system and your power bills feel high
• You’re building a new home and want to set it up efficiently from the start
• You’re already thinking about a heat pump for space heating - combining both systems makes good sense
• You have higher hot water demand (families, teenagers, regular guests)
It’s a bit less suited to very small households with minimal hot water use, where the payback period is longer - though it still delivers savings over time.
What’s the next step?
If you’re curious whether a hot water heat pump makes sense for your home, give us a call or pop into our showroom on Church Street in Timaru. We’ve been helping South Canterbury families heat their homes - and their water - for over 25 years, and we’ll give you a straight answer on whether the investment stacks up for your situation.
Call us on 03 684 5298 or get in touch here to talk it through.