Technical data
94 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
8 Integration of the heat pump in the heating system
8 Integration of the heat pump in the heating system
8.1 Hydraulic requirements
During the hydraulic integration of a heat pump, it must be kept
in mind that the heat pump only has to generate the actual re-
quired temperature level to increase efficiency. The objective is
to feed the temperature level generated by the heat pump di-
rectly (unmixed) into the heating system.
NOTE
A mixed heating circuit only becomes necessary when two different tem-
perature levels have to be supplied (e.g. for underfloor and radiator heat-
ing systems).
To prevent a mixing of the different temperature levels, the heat-
ing operation is stopped during a domestic hot water demand
and the heat pump is operated with the higher flow temperatures
necessary for domestic hot water preparation.
The following basic requirements must be fulfilled:
Guarantee frost protection Chapt. 8.2 on page 94
Safeguard the heating water flow rate
Chapt. 8.3 on page 95
Ensure the minimum runtime
Living comfort must still be ensured when setting the setpoint/
heating curve, but the setpoint/heating curve should not be set
higher than absolutely necessary.
NOTE
For each Kelvin increase in the flow temperature, the efficiency of the
heat pump heating system reduces by 2.5 %.
In order to keep the flow temperature for the heating of a building
as low as possible, the heating distribution system must be di-
mensioned for the flow temperature. The following examples are
suitable for operation with low flow temperatures:
Underfloor heating
Concrete core activation
Fan convectors
Radiant ceiling panels
Ventilation register with extended heat exchanger area
NOTE
In buildings with low flow temperatures, additional electric radiators
should be included in the bathroom. The low flow temperatures alone are
not usually sufficient to dry hand towels adequately. It is also not advisa-
ble to use a heating cartridge in a radiator filled with water.
8.2 Guarantee frost protection
If a heat pump is positioned outside or if outside air flows through
the heat pump, measures must be taken to prevent a freezing of
the heating water during standstill periods or faults.
If a minimum temperature on the frost protection sensor (flow
sensor) of the heat pump is not reached, the heating- and auxil-
iary circulating pumps are activated automatically to ensure that
the frost protection is maintained. In mono energy or bivalent
systems, the second heat generator is released in case of heat
pump faults.
ATTENTION!
In heating systems with utility company shut-off times,the supply cable
for the heat pump manager must be supplied with constant voltage (L/N/
PE~230 V, 50 Hz) . For this reason, it should be tapped upstream from the
utility blocking contactor or be connected to the household current.
The heating circuit should be operated with a suitable antifreeze
if heat pump systems are implemented in buildings where a
power failure can not be detected (e.g. holiday home).
ATTENTION!
If the heat pump is operated with a water/glycol mixture with a glycol
portion of 25%, the efficiency during heating and cooling is reduced by
approx. 15%.
In constantly occupied buildings the use of antifreeze in the heat-
ing water is not recommended since the frost protection is en-
sured to the greatest possible extent through the heat pump con-
troller and an antifreeze reduces the efficiency of the heat pump.
A method of manual drainage should be provided for heat pumps
which are exposed to frost. The system should be drained at
three locations, and if required, blown out whenever it is taken
out of service or in the event of a power failure.
Fig. 8.1: Circuit diagram for installation of a heat pump exposed to frost
ATTENTION!
The hydraulic integration must be carried out in such a way that the flow
is maintained through the heat pump - and thus the integrated sensors -
at all times even in case of a special integration or bivalent operation.
+HDWSXPS