Technical data

16 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
1.3.4.3 Selection and design of heat pumps
The approach is illustrated by the example from Fig. 1.3 on page
15 with a total heat consumption for the house of 11.0 kW at a
standard outside temperature of -16 °C and a selected room
temperature of +20 °C. The diagram shows the heat output
curves of two heat pumps at a heating water flow temperature of
35 °C. The intersection points (limit temperature or bivalence
point) of the straight line of the heat consumption of the building
in relation to the outside temperature and the heat output curves
of the heat pumps are approx. -5.0 °C for HP 1 and approx. -9 °C
for HP 2. HP 1 would be used for the selected example. A sup-
plementary electric heating system is used to enable year-round
heating. This compensates for the difference between the heat
consumption of the building in relation to the outside temperature
and the heat output of the heat pump for the corresponding air in-
take temperature.
Design of the supplementary electric heating
system:
Example:
HP 1 should be dimensioned with a heating element that has an
electrical output of 6.0 kW for the selected example.
1.3.4.3 Design of brine-to-water and water-to-water heat pumps (monovalent operation mode).
Fig. 1.4 shows the heat output curves of brine-to-water heat
pumps. The heat pump with a heat output which is above the in-
tersection of the required total heat consumption and the temper-
ature of the available heat source is to be selected.
Fig. 1.4: Heat output curves of brine-to-water heat pumps with different heat
outputs for flow temperatures of 35 °C.
The output curve of HP 5 must be selected for a maximum re-
quired flow temperature of 35 °C for a total heat consumption of
13.8 kW and a minimum brine temperature of 0 °C. This yields a
heat output of 14.5 kW for the above boundary conditions.
Total heat consumption on the coldest day
– Heat output of the heat pump on the coldest day
= Output of the heating elements
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Building data:
 Monovalent operating mode
(heat pump only)
 Heating system with a maximum
flow temperature of 35 °C
 Shut-off time 6 hours
(factor f from Tab. 1.3 on p. 13)
 Heat consumption heating 10.6 kW
Calculation:
required heat output of the heat pump
= heat consumption heating x factor f
= 10.6 kW x 1.3 = 13.8 kW
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