EN-30
9.6
English
9.5.1 Heat Pumps with One Compressor
Criteria for a switchover:
From L1 to L3 if the heating controller demands “more heat”
for more than 60 minutes and the external temperature
simultaneously remains under the limit temperature of the
2nd heat generator for more than 60 minutes.
From L3 to L1 if the heating controller demands “less heat”
for more than 15 minutes or the limit temperature is
exceeded.
9.5.2 Heat Pumps with Two Compressors
Criteria for a switchover:
From L1 to L2 if the heating controller demands “more heat”
for more than 25 minutes,
From L2 to L3 if the heating controller demands “more heat”
for more than 60 minutes and the external temperature is
simultaneously under the limit temperature for more than 60
minutes.
From L3 to L2 or L1 if the heating controller demands “less
heat” for more than 15 minutes or the limit temperature is
overshot.
From L2 to L1 if the heating controller demands “less heat”
for more than 15 minutes.
In power stage L1, one of the heat pump's compressors is
switched on or off according to the “more” or “less” signals from
the heating controller. In stage L2, one of the heat pump's
compressors operates continuously to cover the base load. The
second compressor is switched on or off according to the “more”
or “less” signals from the heating controller. In stage L3, both
compressors operate continuously to cover the increased base
load. The 2nd heat generator is regulated. Only one compressor
ever operates during defrosting.
9.5.3 High-temperature Air-to-Water Heat Pumps
Normally, only 1 compressor operates at external temperatures
over 10 °C. If the external temperature is under 10 °C and the
flow temperature higher than 50 °C, both compressors are
enabled:
The 1st compressor is switched on initially, followed shortly
afterwards by the 2nd compressor. If the request is no longer
pending or a block is activated, both compressors are switched
off simultaneously.
In respect of the power stage, the high-temperature heat pump
responds like a heat pump with 1 compressor in this temperature
range independent of the selection in the configuration menu, i.e.
there is no power stage 2.
If the conditions for switching to power stage 3 as specified in
Chap. 9.5.1 on p. 30 are fulfilled, the 2nd heat generator is
enabled.
9.6 Hysteresis
The so-called hysteresis for different requests can be set in the
“Settings” menu. The hysteresis forms a “neutral zone” around
the corresponding set temperature. If the current temperature is
lower than the reduced set temperature around the hysteresis,
the request is then recognised. This request remains pending
until the current temperature exceeds the upper limit of the
neutral zone. This results in a switching cycle around the set
value.
Hysteresis of the return set temperature
A hysteresis can be set around the return set temperature for the
heating request.
If the hysteresis is large, the heat pump will operate longer,
whereupon the temperature fluctuations in the return flow are
correspondingly large. A smaller hysteresis reduces the
compressor runtimes and the temperature fluctuations.
For panel heating with relatively flat characteristic curves, set a
hysteresis of approx. 1 K as a hysteresis that is too large can prevent the
heat pump from switching on.
Power stage
Heat pump with
one compressor
Heat pump with
two compressors
Stage L1 One compressor switching only One compressor switching only
Stage L2 - 1 compressor base load, 1 compressor
switching
Stage L3 One compressor and 2nd heat generator, if
required
Both compressors and 2nd heat generator
Defrost Compressor running One compressor running
DHW heating Compressor running One or two compressors running depending on
the external temperature
Swimming pool heating Compressor running One or two compressors running depending on
the external temperature
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