Installation manual

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Selection and Design of Heat Pumps 1.1.4
Fig. 1.2: Diagram for experimental determination of the actually required system temperatures
1.1.3 Which renovation measures must be carried out for energy-saving heat pump
operation?
Low-temperature
Flow temperature for all rooms max. 55 °C
If the required flow temperature is below 55 °C, no additional
measures are required. Any low-temperature heat pump for flow
temperatures up to 55° C can be used.
Medium-temperature
Flow temperature in some rooms higher than 55 °C
If the required flow temperature in some rooms is higher than
55 °C, measures must be taken to reduce the required flow
temperature. In this case, only the radiators in the affected rooms
are replaced to enable the use of a low-temperature heat pump.
Medium-temperature
Flow temperatures in almost all rooms
between 55 °C and 65 °C
If temperatures between 55 °C and 65 °C are required in almost
all rooms, the radiators in most of the rooms must be replaced.
As an alternative, the decision can be made to use a medium-
temperature heat pump instead.
High-temperature
Flow temperatures in almost all rooms
between 65 °C and 75 °C
If flow temperatures ranging from 65 °C to 75 °C are required,
the complete heating system must be converted or adapted. If it
is not possible or not desirable to carry out such a conversion, a
high-temperature heat pump must be installed instead.
A reduction in heat consumption achieved by
 replacing windows
 reducing ventilation losses
 insulating ceiling spaces, attics and/or facades
yields a savings when retrofitting with a heat pump in four
different ways.
a) By reducing the heat consumption, a smaller and therefore
cheaper heat pump can be installed.
b) A lower heat consumption leads to a reduction in the annual
energy demand which must be met by the heat pump.
c) The lower heat consumption can be met with reduced flow
temperatures, which therefore improves the annual
performance factor.
d) Improved thermal insulation leads to an increase in the
mean surface temperatures of the space-enclosing
surfaces. As a result, the same degree of comfort can be
achieved at lower room temperatures.
For example:
A house with a heat consumption of 20 kW and an annual energy
consumption for heating of approx. 40,000 kWh is heated with a
hot water heating system with a flow temperature of 65 °C (return
flow 50 °C). By carrying out thermal insulation measures
retrospectively, the heat consumption can be cut by 25 % to 15
kW and the annual energy demand for heating can be cut to
30,000 kWH.
In this way, the required flow temperature can be lowered by
approx. 10 K, cutting the energy consumption by a further 20 - 25
%. The total savings in energy costs when implementing a heat
pump heating system amounts to approx. 44 %.
NOTE
The following generally applies for heat pump heating systems:
Every 1°C reduction in the flow temperature yields a savings in energy
consumption of approx. 2.5 %.
1.1.4 Choice of heat source (renovation)
It is rarely possible to install a ground heat collector, borehole
heat exchanger or well system in the renovation market for
existing houses with landscaped gardens. In most of the cases,
the outside air is the only possible heat source.
Air is available everywhere as a heat source and can be used at
any time without requiring approval. The annual performance
factors which are to be expected are lower than is the case when
either water or geothermal systems are implemented. At the
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