Ground & Air Source Heat Pumps
Ground Source Heat Pumps
Ground source heat pumps (GSHPs) use pipes that are buried in the garden to extract heat from the ground. This heat can then be used to heat radiators, underfloor or warm air heating systems and hot water in your home.
A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe, called a ground loop, which is buried in your garden.
Heat from the ground is absorbed into the fluid and then passes through a heat exchanger into the heat pump.
The ground stays at a fairly constant temperature under the surface, so the heat pump can be used throughout the year.
The length of the ground loop depends on the size of your home and the amount of heat you need.
Longer loops can draw more heat from the ground, but need more space to be buried in. If space is limited, a vertical borehole can be drilled instead.
Air Source Heat Pumps
Benefits of air source for every 1kw you put into the system air source will convert it to 3kw of heating and ground source will generate 4kw of heating.
Although air source is 25% less efficient than ground source it does not need to have an area excavated to draw heat form. So for retro fitting existing homes or even new builds it is normally the first choice.
Government Funding for Heat Pumps
Our Greensource and Greenstore Heat Pumps are eligible for the UK governments Renewable Heat Incentive (RHI) scheme.
Renewable Heat Incentive (RHI)
The Renewable Heat Incentive (RHI) is the world’s first long-term financial support programme for renewable heat. The RHI will pay participants of the scheme to generate and use renewable energy to heat their buildings.
The domestic RHI is targeted at, but not limited to, homes off the gas grid. Those without mains gas have the most potential to save on fuel bills and decrease carbon emissions.
Tariffs have been calculated by The Department of Energy and Climate Change (DECC) and will change annually in-line with the previous year’s Retail Price Index.
All payments are made directly to the homeowner retrospectively every quarter over a period of seven years. The tariffs are per kilowatt hour of renewable energy produced by each of the following technologies:
Renewable Product Price per kWh
Air Source Heat Pumps 7.3p per kWh
LECP Ground Source Heat Pump 18.8p per kWh
Solar Thermal 19.2p per kWh
Heat pumps and solar thermal tariffs can be jointly claimed providing they are in the same property.
For more details, visit the RHI government website .
How It Works
A heat pump is an electrical device that extracts heat from one place and transfers it to another. The heat pump is not a new technology; it has been used around the world for decades. Refrigerators and air conditioners are both common examples of this technology.
Heat pumps transfer heat by circulating a substance called a refrigerant through a cycle of evaporation and condensation. A compressor pumps the refrigerant between two heat exchanger coils. In one coil, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings. The refrigerant is then compressed en route to the other coil, where it condenses at high pressure. At this point, it releases the heat it absorbed earlier in the cycle.
Refrigerators and air conditioners are both examples of heat pumps operating in the reverse (cooling) mode. A refrigerator is essentially an insulated box with a heat pump system connected to it. The evaporator coil is located inside the box, usually in the freezer compartment. Heat is absorbed from this location and transferred outside, usually behind or underneath the unit where the condenser coil is located. Similarly, an air conditioner transfers heat from inside a house to the outdoors.
Heat pumps can provide year-round climate control for your home. Since the air outside always contains some heat, a heat pump can supply heat to a house even on cold winter days. In fact, air at –18°C contains about 85 percent of the heat it contained at 21°C.
Heat Pump Components
The refrigerant is the liquid/gaseous substance that circulates through the heat pump, alternately absorbing, transporting and releasing heat.
The reversing valve controls the direction of flow of the refrigerant in the heat pump and changes the heat pump from heating to cooling mode or vice versa.
A coil is a loop, or loops, of tubing where heat transfer takes place. The tubing may have fins to increase the surface area available for heat exchange.
The evaporator is a coil in which the refrigerant absorbs heat from its surroundings and boils to become a low-temperature vapour. As the refrigerant passes from the reversing valve to the compressor, the accumulator collects any excess liquid that didn’t vaporize into a gas. Not all heat pumps, however, have an accumulator.
The compressor squeezes the molecules of the refrigerant gas together, increasing the temperature of the refrigerant.
The condenser is a coil/heat exchanger in which the refrigerant gives off heat to its surroundings and becomes a liquid.
The expansion device lowers the pressure created by the compressor. This causes the temperature to drop, and the refrigerant becomes a low-temperature vapour/liquid mixture.