Plantroom Heating And Cooling Schematics - Kensa Group Kensa Heat Pumps P250X Manual

4.3 Plantroom heating and cooling schematics

In many modern commercial buildings, with the improvement in energy saving measures such as insula-
tion, the requirement for cooling is now almost as great (if not greater) than the requirement for heating.
This cooling requirement is generally being driven by the use of heat emitting devices such as computers
and printers and even the staff themselves.
Kensa's commercial ground source heat pump range can be designed as reverse cycle modules which can
provide heating or cooling. This option needs to be specified at time of order as it cannot be field fitted.
For reverse cycle units glycol needs to be added to the distribution side (22%, -10C).
The modular design of Kensa plant rooms enables the system to closely match the required loads. Each
unit should be configured via the BMS to operate sequentially to allow part operation to match the heat/
cooling demand of the building. With multiple units it is possible to provide heating and cooling to differ-
ent parts of the building simultaneously. The multiple unit approach also offers a degree of redundancy
in the unlikely event of a problem with one if the units.
Depending on the system design it might be necessary to incorporate a buffer vessel to avoid short cycling
problems and it is recommended, to improve overall efficiency of the system, that this is a twin connec-
tion buffer vessel. The vessel should be sized for 10 litres per kW of the smallest heat pump module. For
example for a 60kW heating load using 3 x 20kW heat pumps the buffer vessel should be approx 20 x 10 =
200 litres.
Kensa heat pumps can work equally as well with horizontal, vertical or lake arrays as the energy source.
Although Slinky ground arrays are shown on the drawing, in large commercial projects it can be more usu-
al to use a borehole field design due to space considerations.
The following schematic details how a heating and cooling system can be designed, however each heating
and cooling system should be designed for each application.
Principle of operation
In the following example two of the ground source heat pumps are designed as reverse cycle units and
one as heating only. If there is a demand for cooling the heat pump modules can be switched by the Build-
ing Management System (BMS) to cooling mode by the use of a simple volt free relay. At the same time
the BMS system will divert the flow from the heating circuit to the cooling circuit by means of a three port
diverting valve (3PDV) in the flow line. The return flow to the heat pump is also diverted from the heating
circuit to the cooling circuit and the heating pumps turned off and the cooling pumps started.
It is important that a sufficient quantity of glycol antifreeze (minimum 22%, Refractive index 1.356) is
added to the cooling and heating circuit fluid to avoid freezing of the fluid in cooling mode. Failure to do
this will invalidate the warranty.
Abbreviations
2PCV - 2 port control valve
3PDV - 3 port diverting valve
AAV - Automatic air vent
CHW F– Chilled water flow
CHW R– Chilled water return
HTG F - Heating flow
HTG R - Heating return
GSHP - Ground source heat pump
Plant Room Heat Pump Manual Version 11.1
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IV - Isolation valve
LTHW - Low temperature hot water
NRV - Non return valve
P - Pressure gauge
PV - Purge valve
STR - Strainer
T - Temperature gauge
TP - Temperature/ pressure sensor