System overview 3
0020250185_00 geoTHERM Operating instructions 9
hot water is generated only by the gas-
fired boiler.
The heat pump is equipped with an ad-
ditional cooling function that you can use
to cool the living rooms when the outdoor
temperature is higher during summer.
3.5 Safety devices
3.5.1 Frost protection function
The frost protection function for the sys-
tem is controlled via the system control.
If the system control fails, the heat pump
guarantees limited frost protection for the
heating circuit.
3.5.2 Protection against low heating
water pressure
This function continuously monitors the
pressure of the heating water in order to
prevent a possible loss of heating water.
An analogue pressure sensor switches off
the heat pump if the water pressure drops
below the minimum pressure. It switches
the heat pump on again if the water pres-
sure reaches the operating pressure.
– Minimum heating water pressure:
≥ 0.05 MPa (≥ 0.50 bar)
– Heating water operating pressure:
≥ 0.07 MPa (≥ 0.70 bar)
3.5.3 Brine pressure detector
The brine loss protection system continu-
ously monitors the fluid pressure in the
environment circuit in order to prevent a
possible shortage of fluid.
An analogue pressure sensor switches off
the heat pump if the fluid pressure drops
below the minimum pressure. It switches
the heat pump on again if the fluid pres-
sure reaches the operating pressure.
– Minimum brine fluid pressure:
≥ 0.05 MPa (≥ 0.50 bar)
– Brine fluid operating pressure:
≥ 0.07 MPa (≥ 0.70 bar)
3.5.4 Freeze protection
This function prevents the evaporator from
freezing when the heat source temperat-
ure drops below a certain value.
The outlet temperature of the heat source
is constantly measured. If the outlet tem-
perature of the heat source falls below a
certain value, the compressor temporarily
switches off and displays a status mes-
sage. If this fault occurs three times in suc-
cession, the unit is permanently shut down
and displays a fault message.
3.5.5 Pump- and valve-blocking
protection system
This function prevents the pumps for heat-
ing water and brine and all diverter valves
from sticking. The pumps and the valves,
which were out of operation for 23 hours,
are switched on for 10 - 20 seconds, one
after the other.
3.5.6 High-pressure pressure switch
in the refrigeration circuit
The high-pressure pressure switch shuts
down the heat pump if the pressure in the
refrigeration circuit is too high.
If the pressure in the heat pump's refriger-
ation circuit exceeds the maximum pres-
sure, the high-pressure pressure switch
temporarily shuts down the heat pump.
Following a waiting period, another at-
tempt is made to start the heat pump. After
eleven failed start attempts in succession,
a fault message is displayed.
– Max. refrigeration circuit pressure: 4.15
MPa (g) (41.50 bar (g))
– Waiting period: 5 minutes (after the first
occurrence)
– Waiting period: 30 minutes
(after the second and every further oc-
currence)
The fault counter is reset if both of the
following conditions are met:
