Heat Pumps

8.5 kW Mitsubishi Ecodan ASHP.

Heat pumps use the refrigeration cycle to transfer heat from the air, water or ground to the inside of a building to provide space heating and hot water. Heat pumps are powered by electricity, but are more efficient that conventional electrical heating systems.

Heat Pumps - Specifications
Types of System The most common types are Ground Source Heat Pumps (GSHP) and Air Source Heat Pumps (ASHP) A GSHP collects heat via a 'ground loop', which is a length of pipe buried in the ground. The ground loop can be installed in vertical boreholes (more expensive but needs less space) or horizontal trenches (cheaper but large space requirement) ASHPs do not require a ground loop so are cheaper to install and require less space. They source heat from the outside air, which fluctuates more than the ground temperature, therefore they are a little less efficient than GSHPs
Efficiency The efficiency is described as the ‘coefficient of performance’ (CoP) which is the ratio of electricity input: heat output. GSHP CoP approx. 3.5 - 4 ASHP CoP approx. 2.5 - 3
System Requirements Heat pumps are not suitable for all properties. They work more efficiently with a low temperature heating system and are therefore suited to energy efficient, well insulated buildings and are ideally partnered with underfloor heating. However, there is scope for flexibility in the system design – heat pumps can be used with radiators and can be 'docked' with existing heating systems which can be bought in to assist the heat pump during very cold weather. In order to establish the right size of heat pump for your home, a 'heat loss' or SAP calculation is required.
System Costs Typical 8kW system: ASHP: £8-10,000 GSHP (trenched ground loop): £10-12,000 GSHP (borehole installed ground loop): £13-15,000 These costs do not include the cost of the distribution system (radiators or underfloor heating, although do include connection to an existing system)
Running Costs Cost of electricity to run the heat pump and water circulation pump. Consider running the heat pump on a special electricity tariff offered by some suppliers. Scottish Hydro E10.
Development Issues GSHPs are now classed as permitted development, however planning permission will be required for an ASHP.
More information Heat Pump Association: www.heatpumps.org.uk www.energysavingtrust.org.uk/Generate-your-own-energy/Ground-source-heat-pumps

Heat Pumps - Specifications

Types of System

The most common types are Ground Source Heat Pumps (GSHP) and Air Source Heat Pumps (ASHP)
A GSHP collects heat via a 'ground loop', which is a length of pipe buried in the ground. The ground loop can be installed in vertical boreholes (more expensive but needs less space) or horizontal trenches (cheaper but large space requirement)
ASHPs do not require a ground loop so are cheaper to install and require less space. They source heat from the outside air, which fluctuates more than the ground temperature, therefore they are a little less efficient than GSHPs

Efficiency

The efficiency is described as the ‘coefficient of performance’ (CoP) which is the ratio of electricity input: heat output.

GSHP CoP approx. 3.5 - 4
ASHP CoP approx. 2.5 - 3

System Requirements

Heat pumps are not suitable for all properties. They work more efficiently with a low temperature heating system and are therefore suited to energy efficient, well insulated buildings and are ideally partnered with underfloor heating.

However, there is scope for flexibility in the system design – heat pumps can be used with radiators and can be 'docked' with existing heating systems which can be bought in to assist the heat pump during very cold weather.

In order to establish the right size of heat pump for your home, a 'heat loss' or SAP calculation is required.

System Costs

Typical 8kW system:

ASHP: £8-10,000
GSHP (trenched ground loop): £10-12,000
GSHP (borehole installed ground loop): £13-15,000
These costs do not include the cost of the distribution system (radiators or underfloor heating, although do include connection to an existing system)

Running Costs

Cost of electricity to run the heat pump and water circulation pump. Consider running the heat pump on a special electricity tariff offered by some suppliers. Scottish Hydro E10.