Heat pump hot water systems are the most efficient way to heat water in a home. The way they work is not obvious, and the name does not help. A heat pump does not make heat the way an old electric element does. It moves heat from one place to another. This guide explains how a heat pump hot water system works. It covers why that makes it so much lower-cost to run. It also shows how it fits a Perth home with solar.
In one sentence: a heat pump uses a small amount of electricity to draw warmth out of the surrounding air. It moves this warmth into a tank of water. This is why it delivers several times more heat than the energy it uses.
Moving Heat Rather Than Making It
A conventional electric hot water system uses a resistive element. It works much like a giant kettle. It turns roughly one unit of electricity into one unit of heat. A heat pump works on a completely different principle. It uses the same refrigeration technology as a reverse-cycle air conditioner or a fridge, but in reverse. Instead of removing heat from inside a fridge, it gathers heat from the outside air. It delivers it into a water tank. Because it is moving existing heat rather than generating it from scratch, it does the same job for a fraction of the energy.
The Four Steps of the Cycle
Inside the unit, a refrigerant circulates through a simple four-step loop. The table below sets it out.
| Step | What happens | In plain terms |
|---|---|---|
| 1. Absorb | A fan draws in outside air, and the cold refrigerant absorbs heat from it | The system collects warmth from the air |
| 2. Compress | A compressor squeezes the refrigerant, which raises its temperature sharply | The gathered heat is concentrated and made hotter |
| 3. Transfer | The hot refrigerant passes through a heat exchanger around the tank, heating the water | The heat is handed over to the water |
| 4. Repeat | The refrigerant cools, expands and returns to the start to begin again | The cycle continues until the tank is hot |
The water is stored in an insulated tank. This is exactly like a conventional system. A household has a full tank of hot water ready to use. The difference is entirely in how the water was heated.
Why It Uses So Much Less Energy
The efficiency of a heat pump is measured by its coefficient of performance, or COP. A COP of around 4 to 5 means the system delivers four to five units of heat. That is for every one unit of electricity it draws. Good units such as the iStore achieve this. A conventional element has a COP of about one. In everyday terms, an iStore heat pump uses up to 65 percent less electricity than a traditional electric system. This is to heat the same water. This is where the running-cost savings come from.
The systems Positive Energy Solutions installs use a natural refrigerant called R290. It handles a wide temperature range. It has a very low environmental impact. This is compared with the synthetic refrigerants used in many alternatives.
How It Works With Solar
A heat pump draws only a modest amount of power. It includes a timer. This makes it a natural partner for solar. Set it to run in the middle of the day. It heats the tank using the surplus solar a home is generating. That energy would otherwise be exported to the grid for a few cents. The tank then holds that heat as ready hot water for the evening. The system stores solar energy as hot water. This turns a major household load into something close to nothing for a home with solar.
Why It Suits Perth
Perth conditions suit a heat pump well. A heat pump runs more efficiently in warmer air. Perth’s long warm seasons help it perform near its best for much of the year. The strong midday solar gives it plenty of low-cost energy to run on. Combined with the fact that hot water is one of the largest energy costs in a home, that is why a heat pump is one of the most effective upgrades a Perth household can make.
How Positive Energy Solutions Can Help
Positive Energy Solutions is an iStore Elite Partner. It installs iStore heat pump hot water systems across the Perth metropolitan area. It sizes and sets them up to run on solar. Every installation is completed by our accredited installers and signed off to Positive Energy’s completion standards. It is backed by a 10-year installation workmanship warranty. This is on top of the iStore product warranty. It is also backed by Positive Energy Protection, powered by Omnidian. The system is supported well after it is switched on.
Frequently Asked Questions
How does a heat pump hot water system work?
A heat pump uses a small amount of electricity to run a refrigeration cycle. That cycle draws heat out of the surrounding air. It moves the heat into a water tank. Because it moves existing heat rather than generating it with an element, it heats a full tank of water. It uses far less energy than a conventional electric system.
Why is a heat pump so efficient?
Because it moves heat rather than creating it. Its coefficient of performance is around 4 to 5. It means it delivers four to five units of heat for every unit of electricity it uses. That is compared with about one for an electric element. A heat pump uses up to 65 percent less energy for the same hot water.
Does a heat pump work in cold weather?
Yes. Heat pumps are designed to extract heat from the air across a wide temperature range. This includes cool Perth mornings. The R290 refrigerant helps with this. They run most efficiently in warmer air. Perth’s mild climate suits them well for most of the year.
Can a heat pump run on solar?
Yes. A heat pump draws only a modest amount of power. It has a timer. So it can be set to run in the middle of the day on surplus solar. It effectively stores that solar energy as hot water for the evening. For a home with solar, that makes hot water close to nothing.
Heat Your Water for a Fraction of the Cost
A heat pump is a simple idea that delivers a big saving. This is especially true paired with solar. Working out the right system and setup for a specific Perth home is exactly what a Positive Energy Solutions consultation is for.
Talk to the local team about a heat pump for your Perth home: request your quote from Positive Energy
About the Author
Jason Wiktorowicz
Sales Manager, Positive Energy Solutions | Perth, WA
Jason has been at the centre of Western Australia’s energy transition for over a decade. He was Orchestration Lead on Project Symphony. That was WA’s largest virtual power plant pilot. He was Stream Lead on Project Encore. He worked directly with AEMO, Western Power and Energy Policy WA. This work was to shape how distributed energy resources connect and operate on the SWIS. That work included developing and rolling out CSIP-AUS. It is now mandatory for all new WA grid connections. He also led Emergency Solar Management. It was the first program of its kind in WA. He led VPP for Schools. It provided direct market benefits through Supplementary Reserve Capacity. He led REBAR, the WA Residential Battery Rebate scheme.
At Positive Energy Solutions, Jason leads sales with a focus on system design accuracy and long-term performance. Positive Energy Solutions installs solar and battery systems. It installs EV chargers and heat pumps. It holds partner accreditations with Fronius, SigEnergy, iStore and SunPower.
10-year installation workmanship warranty. Positive Energy Protection, powered by Omnidian, performance monitoring included on all systems.
