What is a heat pump and how does it work?

The heat pump is a device that extracts heat from a source and transfers it to another area, much like your typical refrigerator, only instead of getting rid of heat, the heat pump makes use of it.

The sun warms up our atmosphere and the outer layer of the earth’s crust each day, providing massive amounts of thermal energy that are stored in the air that we breathe and under the ground that we walk on.

A heat pump system consists of:

• the heat source (the air, ground or a nearby water body)
• the heat pump (which has an expansion valve, compressor and evaporator)
• the heat distribution system (underfloor heating, radiators and domestic hot water)

The Heat Cycle:

1. EVAPORATOR: Low-grade energy is absorbed from the heat source and raises the temperature of the heat pump refrigerant to change from liquid to gas.
2. COMPRESSOR: The refrigerant is then compressed to significantly lower its volume but increase its temperature.
3. CONDENSER: A heat exchanger then extracts heat from the circulating refrigerant and transfers it to the heat distribution system.
4. EXPANSION VALVE: The refrigerant condenses back into a liquid and is passed through an expansion valve to absorb more energy and begin the cycle again.

The cycle is reversible for cooling mode to achieve lower temperatures in your room during hot periods.

A heat pump can produce 3-5kW of energy for every 1kW of electricity used to power the compressor, giving it an efficiency of 300% or higher. The heat pump’s efficiency is also known as its Coefficient of Performance (CoP). The CoP is simply the ratio between the energy extracted from the heat pump and the energy supplied to run the compressor, therefore the higher the CoP, the better for you. CoP values are normally quoted under certain conditions, for example, a room temperature of 21°C and a flow temperature of 35°C (the temperature of the water leaving the heat pump).

• Ideal for remote locations not on the gas grid

The type of heat pump you select depends on the source of natural energy used by the heat pump. Arctic Air offers:

Outdoor unit for an air-source heat pump                   Borehole drilling for a ground-source heat pump

Air-source heat pumps extract energy from the air and can be used all year round, even at temperatures as low as -25°C. They require low installation costs and minimal space requirements.  Air-to-air heat pumps can be used for space heating or cooling while air-to-water heat pumps provide for domestic hot water and swimming pools.

Ground-source heat pumps obtain energy from the ground either through laying down horizontal collectors at about 1.5m underground (as straight collectors or coiled ones known as "slinkies") or by drilling vertical boreholes up to 100m deep. Due to the stability of the temperature in the ground (roughly 7-10°C), these heat pumps provide high levels of efficiency. As with air-source heat pumps, the ground-source heat pumps can be used for both space-heating or cooling and heating domestic water and swimming pools.

The table below can be used to give you an idea of which type is best suited to your project.

Installing a heat pump with Arctic Air allows you to access funding for your project as we are Microgeneration Certification Scheme Installers. Find out more about what we can do for you here.