Installation manual

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Domestic Hot Water Preparation and Ventilation with Heat Pumps 6.1.3
Fig. 6.1: Water pipe connections
Pressure drops
The pressure drops of the internal heat exchanger should be
taken into consideration when dimensioning the loading pump for
the domestic hot water cylinder.
Temperature settings for domestic hot water
preparation with the heat pump for heating
purposes
Low-temperature heat pumps have a max. flow temperature of
55 °C. This temperature must not be exceeded during the
preparation of domestic hot water in order to prevent the heat
pump from being switched off by the high pressure controller.
The temperature setting of the controller should, therefore, be
below the maximum attainable cylinder temperature.
The maximum attainable cylinder temperature is dependent on
the output of the installed heat pump and the amount of heating
water flowing through the heat exchanger. The maximum
attainable hot water temperature for heat pumps for heating
purposes is calculated according to Chap. 6.1.3 on p. 149. It
should also be taken into consideration that the thermal energy
stored in the heat exchanger will cause a further reheating of
approx. 3 K. The set temperature can be 2 to 3 K lower than the
desired hot water temperature when preparing domestic hot
water with the heat pump.
6.1.3 Attainable cylinder temperatures
The maximum hot water temperature which can be attained
using a heat pump is dependent on:
 The heat output of the heat pump
 The heat exchanger surface area in the cylinder and
 The discharge rate (volume flow) of the circulating pump.
The domestic hot water cylinder must be selected on the basis of
the max. heat output of the heat pump (summer operation) and
the desired cylinder temperature (e.g. 45 °C).
The pressure drops of the cylinder should be taken into
consideration when dimensioning the hot water circulating pump.
The heat supplied by the heat pump cannot be transferred if the
maximum hot water temperature (HP maximum) to be attained
using a heat pump is set too high on the controller (also see the
chapter Control and Regulation).
When the maximum permissible pressure in the refrigerating
circuit is reached, the heat pump manager's high pressure safety
program switches off the heat pump automatically, blocking hot
water heating for 2 hours.
If the domesctic hot water cylinder is equipped with a sensor, the
set hot water temperature (HP maximum new = current actual
temperature in the domestic hot water cylinder – 1 K) is
automatically corrected.
If higher hot water temperatures are required, the water can be
reheated electrically according to need (flange heater in the
domestic hot water cylinder).
NOTE
The hot water temperature (HP maximum) should be set approx. 10 K
under the maximum flow temperature of the heat pump.
domestic hot water preparation for mono energy heat pump systems is
carried out exclusively by the flange heater whenever the heat pump can
no longer meet the heating requirements of the building on its own.
For example:
Heat pump with a maximum heat output of 14 kW with a
maximum flow temperature of 55°C
Domestic hot water cylinder - 400 litres
Volume flow of the hot water loading pump: 2,0 m
3
/h
Based on Chap. 6.1.7 on p. 153 the result is a
hot water temperature of: ~47 °C
Legend
1) Shutoff valve
2) Pressure reducing valve
3) Test valve
4) Return flow inhibitor
5) Pressure gauge connecting stubs
6) Drain valve
7) Safety valve
8) Circulation pump
9) Outlet
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