
Heat pump function
This exhaust air heat pump uses the heat that is in the building's ventil-
ation air to heat up the accommodation. The conversion of the air's en-
ergy to heating occurs in three different circuits. Free heating energy is
retrieved from the outgoing air (1) from the accommodation and trans-
ported to the heat pump. The heat pump increases the retrieved heat's
low temperature to a high temperature in the refrigerant circuit, (2). The
heat is distributed around the house in the heating medium circuit (3).
Ventilation air
The hot air is transferred from the rooms to the heat pump via the house
ventilation system. Outdoor air is only used if necessary.
A
The fan then routes the air to the heat pump’s evaporator. Here, the air re-
leases the heating energy and the air's temperature drops significantly. The
cold air is then blown out of the house.
B
Refrigerant circuit
A liquid, a refrigerant, circulates in a closed system in the heat pump which
also passes the evaporator. The refrigerant has a very low boiling point. In
the evaporator the refrigerant receives the heat energy from the ventilation
air and starts to boil.
C
The gas that is produced during boiling is routed into an electrically powered
compressor. When the gas is compressed, the pressure increases and the
gas’s temperature increases considerably, from approx. -5°C to approx.
100°C.
D
From the compressor, the gas is forced into a heat exchanger, condenser,
where it releases heat energy to the heat pump’s heating section, whereupon
the gas is cooled and condenses to liquid form again.
E
As the pressure is still high, the refrigerant can pass an expansion valve,
where the pressure drops so that the refrigerant returns to its original tem-
perature. The refrigerant has now completed a full cycle. It is routed to the
evaporator again and the process is repeated.
F
Heat medium circuit
The heat energy that the refrigerant produces in the condenser is retrieved
by the climate system's water, heating medium, which is heated to 55 °C
(supply temperature).
G
The heating medium circulates in a closed system and transports the heated
water's heat energy to the heat pump's integrated hot water heater and the
radiators/heating coils of the house.
H
The heat pump’s integrated water heater is in the heating section. The
heating medium heats the hot water.
I
The temperatures are only examples and may vary between different installations and
time of year.
11Chapter 2 | The heat pump – the heart of the houseNIBE F730