5
Groundtherm - Ground Source Heat Pump -
Installation
GeneRal
1.0 How tHe Heat PUmP woRKS
The Groundtherm units are ground source heat pumps especially
designed to operate in association with closed ground loops. such
loops are inserted into the ground adjacent to the dwelling to be
heated, and can take the form of vertical boreholes, horizontal
trenched pipework, or slinkies.
A water/brine mix pumped through such boreholes or pipe work
extracts heat (mainly solar) from the surrounding ground and
provides a source of heat to the heat pump heat exchanger. The
heat pump then converts this heat to useful energy used for space
heating and domestic hot water. A small amount of electrical
energy is required for this conversion.
The design and installation of the closed ground loop is critical to
the performance of the heat pump and must only be carried out by
experienced and competent persons.
The Groundtherm heat pump operates at a high level of efficiency
and has two modes of operation, one for space heating through
under floor heating or radiators, and a second for higher
temperature domestic hot water (DhW). It is therefore known as a
‘dual temperature’ heat pump.
Typically the use of 1kW of electricity by the heat pump will collect
3kW of energy from the ground and release 4kW into the house.
Groundtherm heat pumps are designed to provide low cost space
and DhW heating in well insulated properties. They also greatly
reduce the emission of carbon dioxide (CO
2
).
2.0 InStallatIon
The heat pumps are compact in design and include easily accessible
connection points for both electrical wiring and plumbing.
Due consideration should be given to frost protection when
installing the heat pump.
If the heat pump is installed outside the property frost protection is
required, either by a frost stat and pipe stat, or by adding antifreeze
inhibitor to the heating system. see section 2.2.1.
An optional weather compensation unit is available if required. see
section 5.4
2.1 eleCtRICal
A separately fused single phase supply is required. see wiring
installation diagrams and external wiring diagrams in section 5.2 & 5.3.
Note that the heat pump is not fitted with an on/off switch, any such
switch required must be fitted as prior to the installation. Power to
the unit is indicated by the red indicator light on the console (mains
lamp).
Groundtherm 3.5 & Groundtherm 5 Units
With all power switched off, remove the front panels of the heat
pump the electric box cover. The supply cable, entering the unit
from the top rear, can then be fed through to connect into the
marked live/neutral/earth terminals.
IMPORTANT
Groundtherm 3.5;
the maximum permissible system impedance
Z max at the interface point on the user’s supply in accordance
with section 6.2 EN61000-3-11 should be 0.35 + j0.22 (complex)
0.41 Ohms at 32.01 degrees (Real). Consult with the supply
authority if necessary, that the equipment is connected only to a
supply of that impedance or less.
Groundtherm 5;
the maximum permissible system impedance Z
max at the interface point on the user’s supply in accordance with
section 6.2 EN61000-3-11 should be 0.26 + j0.16 (complex) 0.3
Ohms at 32.01 degrees (Real). Consult with the supply authority if
necessary, that the equipment is connected only to a supply of that
impedance or less.
2.1.1 eleCtRICal Safety
It is important to ensure that all aspects of the installation comply
with the latest I.E.E Regulations.
The machine should be installed in accordance with EMC
2004/108/EC.
For multiple heat Pump installations, to ensure sequential heat
pump starting in event of mains supply interruption. set timer (on
electric box DIN rail) to incremental values. Example; heat Pump
No1 set to 4mins, heat Pump No2 set to 4mins 30secs, heat
Pump No3 set to 5mins etc.
InConSIStent eleCtRICal SUPPly
The following limits of operation must not be exceeded.
Voltage
Minimum Maximum
single Phase machines 207V
253V
Frequency
47.5hz
52.5hz
N.B The voltage must be measured at the heat pump mains in
terminals with compressor(s) running at the rated load condition.
2.2 PlUmBInG
2.2.1 GRoUnD looP
The Groundtherm 3.5 & 5 units are available with an optional
ground loop kit (Earthpack) consisting of a pump box (including
circulation pump, overheat protection and run LED, charging and
air bleed points). see section 4.4.
Flexible connectors are provided between the pump box and the
specially marked ground loop connection points on the back of the
heat pump (marked ‘to ground loop’ and ‘from ground loop’).
Connections to the pump box from the ground loop should
be carefully made either by the ground loop contractor or in
accordance with their instructions. These connections should then
be leak tested.
Connections to the heat pump from the pump box should also be
carefully made, avoiding any twisting or distortion of the flexible
hoses. The heat pump connections have variable geometry for
easy installation.
All pipe work must then be flushed carefully to remove air, and
then charged with an appropriate water/brine mixture. It should
be remembered that the ground loop water temperature can
occasionally drop below 0
º
C, so an anti-freeze agent must be
included. In the event of top-ups being required during the settling
in period, avoid excessive dilution.
The ground loop pump system incorporates a pressure relief valve
that, in the event of over pressure, may release a mixture of water/
antifreeze. Due consideration needs to be given as to where this
is vented.
The anti-freeze concentration should provide freeze protection to
-10 or -15ºC maximum.
This level of protection will be achieved with approximately
25% concentration of an ethylene glycol based anti-freeze. The
fluid manufacturer’s guidelines should be followed for precise
concentration required.
The anti-freeze fluid used should also contain corrosion, scale
and biocidal inhibitors to ensure the long term performance of the
ground loop, for example hydratech Thermox DTX.
