A detailed look at heat pumps and how they work

Find out what heat pumps are and how they work. Plus the five different types of heat-pump system, their benefits and disadvantages.

Heat pumps take low-grade heat from the ground, water or air and boost it to higher temperatures to make it useable for heating. Boosting temperatures through the heat pump uses conventional refrigeration/air-conditioning technology and, as such, requires the input of electrical energy.

Heat pumps have a number of advantages over other heat sources:

• Minimal maintenance
• No bulky fuel deliveries necessary
• Less plant room space required

The efficiency of heat pumps is defined by their coefficient of performance (CoP). A heat pump will require less electrical power than the quantity of heat it can deliver. The CoP is given as a ratio, which should be greater than one and most likely in the region of 2.5–5, i.e. between 2.5 kW and 5 kW of heat delivered for each 1 kW of input power. Similarly, this ratio can be expressed in average terms over time and is often given as a seasonal performance factor – or SPF. An SPF of 3 means 3 kWh of heat is provided from each 1kWh of electrical energy used. The RHI requires that the SPF for an accredited system is greater than 2.5 and its CoP betters 2.9.

Understand the general principles of how a heat pump works, applicable to all types.

Read an explanation of each of the five types of heat-pump system, how each works, the factors to consider when choosing a system to install and the pros and cons of each.

Learn about the key factors involved in installing an effective heat-pump system.

See worked examples of costs and payback for a 100 kW, 500 kW and 1 MW heat-pump system.