Ground source heat pumps
Ground source heat pumps (GSHP) transfer heat from the ground into
a building to provide space heating and, in some cases, to pre-heat
domestic hot water.
For every unit of electricity used to pump the heat, 3-4 units of
heat are produced. As well as ground source heat pumps, air source
and water source heat pumps are also available.
How does it work?
There are three important elements to a Ground Source Heat Pump -
1) The ground loop. This
comprises of various lengths of pipe buried in the ground, either
in a horizontal or borehole trench. The pipe is filled with a mixture
of water and antifreeze and is usually a closed circuit. This is then
pumped round the pipe absorbing heat from the ground.
2) The heat pump. This
has three main sections:
• the evaporator which takes the
heat from the water in the ground loop.
• the compressor which moves
the refrigerant round the heat pump and compresses the • gaseous
refrigerant to the temperature needed for the heat distribution circuit.
• the condenser – which
gives heat to the hot water tank that feeds the distribution system.
3) Heat distribution system.
This consists of radiators in the house or its under floor heating.
It may also be used for water storage for hot water supply.
How much does it cost?
Installation
A typical installation that produces 6 - 8kW will cost in the
region of £7,000 - £12,000 plus the connection costs
to the distribution system which will vary on the size of the property.
Running costs
The coefficient of performance (CoP) measures the efficiency of a
GSHP system. This is the ratio of units of heat output for each unit
of electricity used to power the compressor and pump for the ground
loop. Typical CoPs range from 3 to 4 although if you use under
floor heating you may achieve even better results. You should consider
switching your electricity tariff to economy 7 or 10 as you benefit
from lower running costs.
Savings
On average you can save £400 - £800 on your heating bills
and 2 - 8 tonnes of C02 per year, dependent on the type of fuel being
replaced.
The BERR funded low carbon buildings programme provides grants to
help with the costs of installing biomass technologies. To be eligible
for a grant you will need to use a certified installer and products.
You can also find details of installers in our UK directory by clicking
the button below.
source:
Energy Savings Trust
