Installation manual
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Integration of the Heat Pump in the Heating System 8.3.1
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 actually
required temperature level to increase efficiency. The objective is
to feed the temperature level generated by the heat pump
directly (unmixed) into the heating system.
NOTE
A mixed heating circuit only becomes necessary when two different
temperature levels must be supplied (e.g. for underfloor and radiator
heating systems).
To prevent a mixing of the different temperature levels, the
heating operation is stopped during a hot water requirement 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
Chap. 8.2 on p. 175
Safeguard the Heating Water Flow Chap. 8.3 on p. 175
Ensure the Minimum Runtime Chap. 8.5 on p. 180
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 the temperature level falls below a minimum temperature level
set at the flow sensor (flow temperature) of the heat pump, the
heat and auxiliary circulating pumps are automatically activated
to ensure frost protection. 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 timesthe supply cable
for the heat pump manager must be supplied with constant voltage (L/N/
PE~230V, 50Hz). 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).
In constantly occupied buildings the use of antifreeze in the
heating water is not recommended since the frost protection is
ensured to the greatest possible extent through the heat pump
controller 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 such 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.
8.3 Safeguard the Heating Water Flow
The minimum heating water flow rate listed in the device
information must be maintained for all operating statuses to
guarantee the functional operation of the heat pump. The
circulating pump should be dimensioned so that the water flow
through the heat pump is also maintained even if there is a
maximum pressure drop in the system (almost all heating circuits
closed).
The required temperature spread can be determined in two
possible ways:
Arithmetical calculation
Chap. 8.3.1 on p. 175
Reading out of tabular values in relation to the heat source
temperature Chap. 8.3.2 on p. 176
8.3.1 Arithmetic calculation of the temperature spread
Determination of the current heat output of the heat pump
from the heat output curves at the average heat source
temperature.
Calculation of the required temperature spread using the
minimum heating water flow rate listed in the device
information.
NOTE
Tabular values for the required temperature spread in relation to the heat
source temperature can be found in Chap. 8.3.2 on p. 176.
Example: Air-to-water heat pump:
Heat output
HP
= 10.9 kW at A10/W35
Specific heat capacity of water: 1.163 Wh/kg K
Required minimum heating water flow rate:
e.g. V = 1,000 l/h = 1,000 kg/h
Required spread:
+HDWSXPS
4