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UAB KOMFOVENT we reserve the right to make changes without prior notice
RHP PRO_22-01
Hea
t pump capacit
y
Air volume
Minimum
airflow to start
heat-pump
Minimum
airflow to allow full
capacity
20%
100%
Limited heat
pump capacity
Fig. 6.
Heat pump capacity limitation according airflow
Heat pump is not operating when outdoor air temperature is between 15°C and 20°C, as, in this case, the rotary heat
exchanger is usually capable of reaching desired air temperature.
If heating/cooling demand increases when the heat pump is switched off, additional heaters/coolers are activated
1
.
When the heat pump is running, we recommend operating air handling units with the smallest pos-
sible air volume difference between the supply and extract airflows. In case of high flow imbalances
(>20%), capacity and efficiency of the heat pump decreases, therefore the compressor operates at
a critical refrigerant pressure limit. This results in reduced operating life and increased probability of
failure.
During winter operation, when the heat pump is in heating mode, condensate on the evaporator starts freezing and
forms frost. Large ice deposits block airflow in the evaporator and may damage the heat pump. Therefore, the evaporator
is automatically defrosted during winter use. When the outdoor temperature drops below zero, the heat pump automation
system starts constantly monitoring pressure difference upstream and downstream the evaporator heat exchanger. When
condensate accumulates in heat exchanger plates and ice starts to form, pressure increases and defrosting actions are initi-
ated. During the defrost cycle, part of the hot refrigerant gas is directed from the compressor to the evaporator to melt for-
ming ice crystals, therefore supply air temperature temporarily drops. Integrated electric or auxiliary heaters are switched on
to compensate for this change. As soon as frost melts and pressure decreases, all the power of the heat pump is redirected
to the heating process.
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Depends on configuration.