Energy Efficiency

Measuring heat pump efficiency

Heat pumps are among the most efficient heating and hot water systems available today.

Approximately 75% of the energy needed for heating comes from the environment. This means that for every 1kWh of electricity used to power the heat pump compressor, between 3 and 4kWh of heating energy are produced, giving the heat pump an efficiency of 300 – 400% or higher. This helps result in:

• Lower heating system carbon dioxide emissions
• Lower heating system running costs

Take a look at our “Benefits of renewable heating” section for more information.

Coefficient of Performance (CoP)

The heat pump’s “efficiency” is known as its “Coefficient of Performance” or CoP. This is simply a ratio between the proportion of the total energy supplied that can be extracted from the environment and the amount supplied by electricity to run the heat pump compressor. The higher the CoP, the more “free” energy the heat pump is using.

Heat pump CoP is affected by a number of factors, most importantly:

• Temperature of the heat source (eg the air)
• Heating water temperature

As these factors vary throughout the heating season, the CoP will also continually vary. CoP will be at its highest when:

• The heat source temperature is high – a high amount of “free” energy is available from the environment
• The heating water temperature is low – the heat pump has to do less work to raise the temperature of the heating system

Dimplex LI TE efficiency

For the purposes of comparison, it is normal to state air source heat pump CoP at an air temperature of 7ºC and water heating temperature of 35ºC (A7/W35), tested to the appropriate EN standard:

LI 16 TE - CoP: 3.7
LI 20 TE (1 / 2 compressors) - CoP: 3.2 / 3.1
LI 24 TE (1 / 2 compressors) - CoP: 3.4 / 3.2
LI 28 TE (1 / 2 compressors) - CoP: 3.1 / 3.4

Performance characteristics and CoP’s of the LI TE range at a range of varying operating conditions are listed in the Technical Specifications section.