Vaillant geoTHERM SERIES, Руководство по установке, Страница: 10 / 132

Description of functions and units
10
Installation instructions geoTHERM 0020051574_04
3
3.2 Functional principle
The Vaillant geoTHERM heat pump VWS uses geothermal
heat as its heat source, whereas the geoTHERM heat pump
VWW uses well/groundwater.
Electric
auxiliary
heater
Domestic
hot water
tank
Heating circuit
Brine circuit/well water circuit
Coolant
circuit
Domestic
hot water
Cold water
Heating/cylinder
charging
diverter valve
Condenser
Heat source
Brine pump/
Well pump
Evaporator
Compressor
Expansion
valve
2
1
3
4
Heating
installation
3.2 Principle of operation of the heat pump
The heat pump consists of separate circuits which are cou-
pled with one another by means of heat exchangers. These
circuits are:
– The brine circuit with which the thermal energy is trans-
ferred from the heat source to the coolant circuit.
– The coolant circuit, which releases the thermal energy to
the heating circuit by means of evaporation, compres-
sion, liquefaction and expansion.
– The heating circuit, which supplies the heating and DHW
loading for the domestic hot water cylinder.
The evaporator ( 1 ) is used to connect the coolant circuit to
the geothermal heat source, from which it extracts thermal
energy. At the same time, the physical state of the coolant
changes; it evaporates. The condenser (
3 ) is used to con-
nect the coolant circuit to the heating installation, to which
it releases the thermal energy again. In so doing, the cool-
ant becomes liquid again; it condenses.
As thermal energy can only pass from a body at a higher
temperature to a body at a lower temperature, the coolant
in the evaporator must have a lower temperature than the
geothermal heat source. On the other hand, the tempera-
ture of the coolant in the condenser must be higher than
that of the heating water in order to be able to release the
thermal energy to it.
These different temperatures are produced in the coolant
circuit by means of a compressor (
2 ) and an expansion
valve ( 4 ) between the evaporator and condenser. The cool-
ant flows in vapour form from the evaporator into the com-
pressor, where it is compressed. This causes the pressure
and temperature of the coolant vapour to rise sharply. After
this process, the coolant flows through the condenser,
where it releases its thermal energy to the heating water by
condensation. It flows as a liquid to the expansion valve,
where it expands significantly and, in so doing, loses much
of its pressure and temperature. This temperature is now
lower than that of the brine/well water flowing through the
evaporator. The coolant can thus take up more thermal
energy in the evaporator, turning into vapour in the process
and flowing to the compressor. The cycle starts again.
If required, an external electric auxiliary heater can be
switched on by the integrated controller.
To prevent condensation from forming inside the unit, the
cables of the brine circuit/well water circuit and the coolant
circuit must be cold insulated. If condensation still occurs,
(
7 )
¬
Fig. 3.5 and
¬
Fig. 3.6 are collected in a condensate
pan and guided under the heat pump. Drop formation under
the heat pump is thus possible.
The geoTHERM heat pump VWS can be equipped with
external passive cooling in order to provide for comfortable,
cool room temperatures in your living rooms at high out-
side temperatures during the summer operation. For this
purpose, additional components are required in the heat
pump hydraulics. An auxiliary cooling heat exchanger, an
additional mixer valve and an auxiliary diverter valve.
In the case of Vaillant heat pumps with cooling function, the
principle of “passive” cooling is applied, in which thermal
energy is transported via underfloor heating from the
rooms to the ground without compressor operation and
therefore without coolant circuit operation. The heating
water, which when supplied is colder than the room temper-
ature, absorbs thermal energy from the rooms and is
pumped via the heating circuit pump into the cooling heat
exchanger. The brine pump also conveys the colder brine
from the ground into the heat exchanger of the brine cir-
cuit, which is operated using the counter flow principle. In
the process, the warmer heating return emits thermal
energy to the colder brine circuit, so that the brine which is
heated to some degree is guided again to the floor. The
annealed heating flow circulates again through the circuit
of the underfloor heating, where the water can reabsorb
thermal energy from the surroundings. The cycle starts
again.