Heat pumps may be the perfect energy transfer solution for year-round comfort, but do you know how they actually work?
Heat pumps may be the perfect energy transfer solution for year-round comfort, but do you know how they actually work? A heat pump unit draws energy into the system from the external environment. This energy is extracted from sources such as water, the ground, or most commonly, the air. Energy is then transferred to the building’s heating or hot water system.
For heating, energy is circulated through radiator panels, underfloor pipework or fan coil units. Many heat pumps are reverse cycle, meaning they can either heat or chill water. Having a reverse cycle heat pump gives you the option of running a hydronic heating or cooling system, ensuring efficient comfort all year round.
So what makes it all work?
Similar to the system you may find within an air conditioner or freezer, a heat pump commonly utilises four main components – an evaporator, compressor, condenser, and an expansion valve. While it uses a very similar cycle to the above systems, a heat pump works in the opposite direction. It pulls heat from cooler external environments or the ground and delivers it to the conditioned space via a hydronic system or into a DHW tank.
The compression cycle
Heat pumps use a vapour-compression refrigeration cycle. This works to stabilise the process of evaporating and condensing fluid known as refrigerant. The refrigerant works as the energy transfer medium between the external energy source and the internal hydronic system’s water.
1. The refrigerant works by absorbing environmental heat through the evaporator (a form of heat exchanger). As the refrigerant in the evaporator is colder than the heat source, the heat energy can be absorbed by the refrigerant as it evaporates.
2. This vaporised heat is then transported to the compressor. Here it is compressed in order to increase the temperature further while also raising the pressure.
3. Now that the vapour is heated, it moves to the condenser (another form of heat exchanger) which transfers the heat from the refrigerant to the water within the hydronic system.
4. The refrigerant then travels through to the expansion valve where it cools and drops in pressure. The fluid is circulated back to the evaporator to restart the heating process.
If the heat pump is capable of cooling in summer, the heating cycle is reversed in order to chill the water within the system.
Why it works so well
Heat pumps use readily available energy from the world around us and efficiently turn that into comfort inside the home. By utilising this free energy source, a heat pump can produce up to 5 times the amount of energy than what is required to run it – making it one of, if not the cheapest heat source to use.
With a growing focus on renewables in the energy sector, a heat pump makes the perfect addition to your hydronic, hot water and cooling system. All in all, they are a flexible, efficient and environmentally conscious choice for your project. Offering value for money, this adaptable system will ensure your building is heated and cooled when required, achieving optimum comfort all year round.