Heat pump hot water systems have matured significantly in recent years after a difficult introduction in Australia that left many homeowners wary. It’s unfortunate because these systems are extremely economical, cutting running costs by around 75% compared with standard electric or LPG gas units. Going cheap, though, usually ends badly — low-cost, unbranded heat pumps are often built with inferior parts and will typically perform accordingly.
Through the mid‑2000s up until about 2015, several major hot water manufacturers produced heat pump units of very poor quality. When government incentives and regulations pushed for solar, gas or heat pump solutions instead of old electric-style heaters, a hurried push to design and produce these systems led to some ill-considered engineering choices that simply didn’t stand up over time.
Even now there are substandard heat pumps being marketed to consumers by high-pressure sales companies, and some inexpensive imported units don’t tolerate Australian conditions well due to their construction and components.
If you understand that lower price usually reflects cheaper components, you’ll choose wisely. The price gap between no-name heat pumps and reputable manufacturers isn’t huge, and the electricity savings when switching from a gas or conventional electric heater to a quality heat pump are substantial.
Call us on 1300 728 122 for completely unbiased, straightforward advice on which systems are reliable and which ones to avoid.
Below I’ll explain how heat pumps work and outline the main types. The simplest way to picture a heat pump is to think of a refrigerator in reverse: where a fridge removes heat and expels warm air, a heat pump draws heat from the air and expels cooler air. Like walking past an air conditioner’s outdoor unit and feeling hot air, a heat pump water heater blows out cold air while extracting heat to warm water via heating plates or coils that are wrapped around or located inside the storage tank. A heat pump typically uses about 1 kW of power compared with roughly 4 kW for a standard electric unit — about 75% less.
Heat pump water heaters extract warmth from the surrounding air and transfer it into the water, which is why they’re often called air‑sourced solar hot water heaters. They run on electricity but are roughly three times more efficient than conventional electric resistance tanks. In suitable conditions they reduce energy use, lower bills and cut greenhouse gas emissions, and they pair very well with rooftop solar PV since their power draw is relatively low (generally around 1 kW versus 3.6 kW for a standard electric heater).
How does a heat pump work?
A heat pump operates on the same basic principle as an air conditioner or refrigerator, but instead of removing heat, it transfers heat into the water through coils or submerged pipes in the storage tank. Some designs circulate tank water through a heating plate and back again. Electricity runs a compressor that pumps refrigerant through the system; the refrigerant absorbs heat from the air and passes it to the water in the tank.
Heat pumps rely on a refrigerant that vaporises at low temperatures. The process includes several stages:
– A liquid refrigerant flows through an evaporator, picking up heat from the air and turning into a gas.
– That gas is compressed by an electric compressor; compression raises its temperature above the tank water temperature.
– The hot gas moves into a condenser, transfers its heat to the water and reverts to a liquid.
– The liquid refrigerant then passes through an expansion valve, reduces pressure, cools and returns to the evaporator to repeat the cycle.
Unlike a traditional electric resistance heater that uses electricity to generate heat directly, a heat pump uses electricity to run the compressor and fan while transferring a larger amount of heat energy from the air to the water, which makes it much more efficient. The amount of heat transferred depends on ambient temperature.
When outside air is warmer than the cold refrigerant, the heat pump readily absorbs heat and moves it into the water. Warmer ambient conditions make the pump more efficient; as temperatures drop, less heat is available, so performance falls — which is why heat pumps are less effective in very cold climates. Some manufacturers now produce systems that operate at sub‑zero temperatures, allowing installation inside large ventilated spaces such as a big garage.
To maintain continuous heat absorption at the evaporator, a steady supply of fresh air is required. A fan forces airflow through the unit and the cooled air is expelled to atmosphere.
Heat pump water heaters come in two main configurations:
– Integrated (compact) systems where the compressor and storage tank are combined into a single package.
– Split systems where the tank and compressor are separate, connected by refrigerant piping much like a split‑system air conditioner.
For reliable installation, repairs or advice from a Maroochydore plumber experienced with hot water systems — gas and electric, installation and repairs — contact Maroochydore Hot Water.
