Heat pumps AIR / WATER
Operation manual 11
2.5 Description of heat pump operation
2.5.1 Heating
ACOND® is a heat pump that generates heat energy for the house according to current needs.
Hot water is heated continuously, or according to the service water heating schedule. In the
event of an increase in the average outdoor temperature (average over 3 days, temperature
measured in the morning, noon and evening) above the value of “End of heating”, the heating
of the house will be stopped.
When a very cold object is heated, the auxiliary heating bar (so-called bivalent
heater) is switched on. When the reverse temperature rises from the system
above 21°C, the heat pump runs according to the set type of regulation (see
chap. 3.2.7 on page 25).
2.5.2 Defrosting
During operation, the air heat exchanger (evaporator) is cooled by a pre-cooled cooling
medium and covered with frost due to the humidity of the outside air. Therefore, an automatic
function for defrosting the air heat exchanger is activated when the ACOND® heat pump is
running.
The defrost sequence starts when the evaporator temperature of the outdoor unit falls below
the set value. The four-way valve in the refrigerant circuit switches the refrigerant flow direction
and the fan stops. The warm coolant does not heat the condenser (plate/tubular exchanger),
but on the contrary warms up the frost on the air heat exchanger. This process ends when the
evaporator temperature reaches the set temperature. The four-way valve switches back the
coolant flow direction and the heat pump recreates the heat energy for the heating system.
During defrosting, the coolant flow direction changes, the air heat exchanger
becomes a condenser and the condenser for heating the heating system
becomes an evaporator. For a short time there is a change in the sound of the
heat pump, which is caused by switching the direction of coolant flow and
changing the pressure conditions in the coolant circuit.
When defrosting the evaporator, heat energy is drawn from the heated heating system of the
house. A storage tank is used to compensate for temperatures.
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