Technical data

12 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
1.1.3 Selection and design of heat pumps
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 is only higher than 55 °C in some
rooms, measures must be taken to reduce the required flow tem-
perature. 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 desired 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 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 consumption which must be met by the heat pump.
c) The lower heat consumption can be met with reduced flow
temperatures, which therefore improves the seasonal per-
formance factor.
d) Improved thermal insulation leads to an increase in the
mean surface temperatures of the space-enclosing sur-
faces. As a result, the same degree of comfort can be
achieved at lower room temperatures.
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
domestic hot water heating system with a flow temperature of
65 °C (return 50 °C). By subsequently carrying out thermal insu-
lation measures, 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 average flow temperature can be lowered by ap-
prox. 10 K, reducing the energy consumption by a further 20-
25%. The total savings in energy costs when implementing a
heat pump heating system amount to approx. 44%.
NOTE
The following applies for all heat pump heating systems:
Every 1°C reduction in the flow temperature yields a saving 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 exist-
ing houses and landscaped gardens. In most 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 seasonal performance
factors which are to be expected are lower than is the case when
either water or geothermal systems are implemented. At the
same time, the costs for tapping the heat source system are
lower.
Refer to the relevant chapters for further information on how to
dimension heat source systems for brine-to-water and water-to-
water heat pumps.