Guidance note
Ground source heat
pumps
Ground source heat pumps can be an efficient way of using electricity to heat
your church, by capturing and boosting heat drawn from underground.
Benefits of ground source
heat pumps
Also, if a heat pump is powered Two metres down, the ground
by a renewable energy source, is protected from extremes of
heat or cold and stays at about
it is completely renewable.
- Lower carbon emissions: an
10°C all year. The heat pump
average ground source heat
uses electricity to boost this
How does it work?
pump could save around 1.8
low-grade heat to the
tonnes of carbon emissions
temperature needed to heat a
every year, when replacing an A ground source heat pump
church.
circulates a mixture of water
oil boiler.
and antifreeze around a loop of Types of GSHP and
- Lower fuel bills: ground
pipe either laid a few metres
installation:
source heat pumps run on
electricity, so there's no need to below the surface or in a
borehole. Heat from the
Horizontal trenches - should be
pay for gas, oil or solid fuels.
ground
is
absorbed
into
this
at
least two metres deep for a
Heat pumps depend on good
fluid
and
is
pumped
through
a
consistent
year-round heat
insulation and can be useful in
heat exchanger, where pipes
source. You will need 50-80
locations not connected to a
containing this relatively warm metres of pipe per kilowatt
gas supply.
water are coiled around pipes (kW), or 10 metres of ‘slinky’
- Less electricity use: heating
containing
the very cold
coiled pipe per kW (7-8kW is a
homes with a ground source
typical size) with at least 5
refrigerant. Warming the
heat pump is much more
metre distance between
refrigerant
before
it
enters
the
energy-efficient than using
trenches with coils. So a typical
compressor.
This
heat
is
electric radiators.
8kW heat pump requires
- As the grid decarbonises, heat mainly solar energy that has
been absorbed by the ground. around 400m2 of ground area
pumps become low carbon.
for slinky coils, perfect if you
have a un used field or area of
land associated with the
church.
Veritcal boreholes - need 20-50
metres of pipe per kW, and will
usually be 50-150 metres deep.
You may need 2-4 pipes per
borehole, or more than one
borehole. The Pipe diameter
should be 20 to 40mm for best
performance. This has the
advantage of needing to disturb
less of the ground (particularly
pertinent where graveyards
surround the church), but there
is the expense of drilling the
bore.
Note: Do remember to check
with your diocese early in the
planning process.
Cost
kilowatt (kW). The heat pump What to expect
itself will be £400 to £600 per
kW, with trenches £300 per
• Since heat pumps provide a
kW or boreholes £500 per kW.
lower temperature heating
compared with boilers,
Earnings
radiators will be warm
rather than hot
You may be able to receive
• A church with radiators
payments for the heat you
may heat up more slowly
generate from a Ground Source • The heat pump will run for
Heat Pump through the
longer hours than a
government’s Renewable Heat
conventional boiler but if
Incentive. Small systems of less
properly controlled will
than 100 kWth are eligible for a
switch on and off with the
generation payment of 4.5
heating requirements of the
(pence/kWh) and large systems
church
can receive 3.2 (pence/kWh).
• A properly sized and
installed heat pump should
Note: You will not be eligible
be able to provide most of a
for the RHI if you have
church’s heating
received a ‘grant from public
requirements but most heat
funds’ for the costs of
pumps are installed with a
purchasing or installing your
supplementary electric
renewable heat installation.
heater.
For best results
At current prices, a heat pump
Case study
should be a cheaper option
• Ensure your church is
than oil, LPG (propane &
St Stephen's, Lympne, Diocese
insulated as much as
butane), or direct electric
possible (e.g. pipes lagged, of Canterbury
heating (e.g. storage heaters).
insulation between roof
However it is unlikely to be
rafters) prior to a heat
more cost effective than a
pump being installed.
modern gas boiler. Heat pumps
• Install the heat pump with
are still a relatively rare option
low temperature underfor central heating, so
floor heating or properly
installation prices will vary –
sized radiators.
the best thing to do is to
•
Insist upon
compare quotes from a few
understandable, userinstallers.
friendly controls.
•
Ensure you have a qualified
As a rule of thumb, a groundinstaller.
source system is likely to cost
about £1000 per installed