Efficiency

The main performance figure of an air source heat pump is the COP (Coefficient of performance). This is the ratio of electricity used to heat output produced. For instance, a heat pump with a COP of 5 means that for every 1kw of heat used, 5kw of heat is produced.

So in money terms, if a unit of electricity costs 34p per kw/h, using the internal heater to produce 5kw of heat it would cost £1.70. An air source heat pump would cost 0.34p to produce the same amount of heat.

Our air source heat pumps can operate in temperatures down to -12c and under average UK temperatures of 10c offering an average COP of 5.6. In peak conditions, this can rise to 16.

Not quite as straightforward as that

The output of an air source heat pump is dependent on a number of variables, these include ambient temperature, water temperature and humidity. So the COP of a heat pump does vary. For instance, at 25c outside the heat pump might have a COP of 7:1, but at 5c the COP will drop to a COP of 4:1.

Another factor is the technology used within the heat pump so the hardware and the refrigerant gas.

Different refrigerant gases perform differently. Modern heat pumps use R32 gas which is usually effective down to around -15c

The second main component is the compressor used, of which there are main two types – on/off and inverter.

Types of air source heat pumps

On/Off

On/Off compressors are either on or off, so all or nothing. They cannot vary their output or power usage. Newer inverter-style air source heat pumps can run at variable speeds, so on a warmer day when less heat is cooled, they can run slower meaning less power is used. The inverter heat pumps use less power than the on/off heat pumps.

Inverter

The second main component is the compressor used, of which there are main two types – on/off and inverter.

The most efficient heat pumps (like what we supply) use inverter technology. So instead of the equipment in the heat pump being either on or off (fan, compressor, expansion valve) they can vary in speed which means they run only as much as required, therefore much more efficiency and cost saving.