Ground source heat pumps work by using heat stored in the ground from the sun’s solar radiation to supply all of the energy required for a home's heating and hot water system.
The top 15 metres of the Earth's surface maintains a relatively constant temperature of approximately 12?C. This energy can be used to heat buildings indirectly. Pipe is buried in the ground, either in a borehole or a horizontal trench. The pipe is usually a closed circuit and is filled with a mixture of water and antifreeze, which is pumped round the pipe, absorbing heat from the ground.   In winter the ground is warmer than the air and buildings above. The anti-freeze mixture absorbs heat from the ground, which is then concentrated and transferred to the buildings.  This heat can be used to heat domestic water and a low temperature heating system such as under floor heating.  The efficiency of a ground source heat pump is measured in Coefficient of Performance (CoP). This is the ratio of units of heat output for each unit of electricity used to drive the compressor and pump for the ground loop.  A CoP of 4 means that for every kilowatt of electricity put in, you get 4 kilowatts of energy out in the form of warm water. The flow temperature of the warm water is typically between 35?C and 45?C; much lower than achieved by a domestic boiler. The units can reach higher temperatures, but the CoP is then compromised. Keeping the temperature at the lower end of the scale ensures the system operates efficiently.

For a 3 bedroom house with a floor area of 150m², as shown in our diagram with current building regulations in place, we assume the part L average heat loss to be 45W/m² which results in producing a heat loss value of 6.75kW.  These heat loss calculations result in the property requiring a 1240, 8kW Ground Source Heat Pump.

The price for a 1240 8kW Ground Source heat pump = £9,783
Installation is estimated @ 72hrs @ £37.50/hr = £2,700
Total Supply & Install Price = £12,483 (+VAT)

• A 1240, 8kW Ground Source heat pump (1 phase) comes complete with integral 160litre mains pressure hot water cylinder, weather compensated controller, easy to operate LCD control screen, soft start compressor, ground loop pump, heating system pump, 3 port control valve and 6kW electric heater.
• The Installation kit includes a hot water expansion vessel, pressure reducing/relief valve, pressure/temperature relief valve and tundish.
• Collector connection assembly.  Connections from 40mm PEM to coppers, filling and flushing valves, pressure gauge and fittings, adaptors from copper to filling vessel, particle filter and heat pump.
• 400m Ground-loop assembly; including 400m ground-loop, ground loop connection assembly, pressure testing assembly and anti-freeze.
• Components for 1240 docking.
• PLEASE NOTE: Trench ground works to be carried out by the customer &, if you do not have the space for trenches, the cost of 1 Bore Hole needs to be added to this price but can be arranged via AlternEnergy.

AlternEnergy will deliver and install the product along with carrying out the final installation checks, add anti-freeze mixture (where applicable), set up the unit, commission and give the customer all the necessary instructions.  We will require an initial deposit of 20% of the price, with the remaining 80% prior to delivery of the heat pump. We are accredited to commission this product to enable eligibility for grant funding – please speak to your project manager for latest information on grants and funding.

Further information on this system is as follows:

• Total Power Demand for heating = 6.75kW
• Net Energy Demand (excl Domestic elect) = 22,197kWH/year
• Hot Water Demand (incl in above) = 4,150kWh/year
• Power demand 7.2kW
• Mean Annual temperature = 9°C
• Design Outside temperature (DOT) = -3°C
• Indoor temperature = 20°C
• Solar & body heat = 14°C
• Flow temperature at DOT = 50°C
• Return temperature at DOT = 40°C

Further information on the Energy Consumption is as follows:

• Degree of energy coverage = 99%    
• Degree of power coverage = 100%
• Annual heating factor HP = 4.0
• Annual heating factor tot = 3.8
• Hot Water from heat pump = 95%
• Energy delivered by heat pump = 21,983kWh/year
• Energy Supplied to heat pump = 5,555kWh/year
• Supplementary energy, net = 208kWh/year
• Supplementary energy, Electricity 100% = 208kWh/year
• Recommended net supply power = 0.0kW
• Gross Energy consumption, electricity = 5,762kWh/year

Therefore, the saving with a Ground Source heat Pump = 16,429kWh/year.