How Do Heat Pumps Work?

In Australia, heat pump hot water systems have become more popular than ever.

The 6Wresearch projects that the heat pump hot water systems market will grow at a CAGR of 10.7% from 2024 to 2030 and for good reason: heat pumps use energy efficiently and are good for the environment.

The reason behind that is that these systems heat water for domestic use without using electric coils or burning fossil fuels. To do this, the system captures heat from the environment using the principles of thermodynamics and then transfers it to the water stored in a tank. 

Think of them operating like a refrigerator but in reverse. Instead of taking heat from the system to achieve cooling effect, heat pumps collect heat from the surroundings to warm a refrigerant.

The heated refrigerant then flows through a coil in the storage water tank where it transfers heat to the water in the tank.

Since this process avoids using electric heating elements, only a small quantity of electricity is needed to pump the refrigerant as it collects and transfers heat.

According to DCCEEW, this process saves about 70% of the energy that would be needed to heat the same amount of water using an electric instantaneous water heater. 

Additionally, the process minimizes greenhouse gas emissions and has the potential to lower it by up to 81% by 2030 as noted by Beyond Zero Emission. 

But how does this remarkable technology function? To understand its inner workings, let’s explore the key components that comprise a heat pump water heater system and what they do. Here we go!

The Fan Pumps the Air 

The working of a heat pump hot water system begins with the fan (in some systems there can be more than one fan) forcing more air to the unit. This increases the exposure of the unit to the ambient air, allowing for greater heat absorption.

The more air forced to the system, the more heat absorbed and this explains why some units have more than one fan.

The Evaporator Allows Heat Absorption

Once the fan forces air through the system, the first and the most important place where this air goes is in the evaporator. The evaporator is made of coiled tubes containing a cold, low-pressure refrigerant.

Since the temperature of the air forced into this system is higher than the temperature of the refrigerant, heat naturally gets drawn towards the coil due to the difference in temperature.

The heat is then absorbed by the refrigerant, increasing its temperature.

The increased temperature transforms the liquid refrigerant into a low-temperature vapor or gas. This gaseous refrigerant then flows towards the compressor.

The Compressor Boosts Refrigerant Temperature

The already heated refrigerant gas then enters into the compressor, where its pressure is increased significantly.

This further raises the temperature turning the low-temperature vapor into a high-temperature vapor.  Now, the high-temperature vapor travels through to the condenser to transfer heat.

The Condenser Coil Transfers Heat to Water

The superheated refrigerant exits the compressor and enters the condenser, a coiled tubing inside the storage tank. As the hot refrigerant flows through this coil, it comes in direct contact with the water in the tank, transferring its thermal energy.

This transfer process increases the water’s temperature to the desired level set by the thermostat.

Expansion Valve Regulates Refrigerant Flow

After transferring heat to water, the refrigerant becomes a liquid again but remains under high pressure.

The expansion valve then plays a crucial role by lowering this pressure. It regulates the refrigerant’s flow from the high-pressure side to the low-pressure side thereby reducing its pressure significantly.

This significant pressure reduction allows the refrigerant to expand and cool down, preparing it to restart the cycle by returning to the evaporator and absorbing more heat from the surroundings. 

The continuous compression, heat transfer, and expansion cycle enables heat pumps to efficiently heat water using minimal electricity and without needing traditional heating coils or burning gasses.

Is a Heat Pump Water Heater Better than an Electric Instant Water Heater for Australian Homes? 

The Thermostat Keeps Temperature under Check

Located at the top of the tank, the thermostat monitors water temperature. When temperatures fall below the target level, the thermostat activates the heat pump.

The fan pulls in warm air; the evaporator absorbs heat, restarting the cycle. If the water temperatures exceeds the set target, the thermostat signals the pump off to prevent energy waste or overheating that can damage the parts of the pump.

Final Thought

That’s how heat pump hot water systems operate. They use less electricity and emit minimal greenhouse gasses into the environment.

This makes them a great choice for anyone looking to lower their energy bills and carbon footprint, while still enjoying domestic hot water systems. Get yours installed today and join those already enjoying these benefits and many more.