Vaillant geoTHERM Installation Instructions Manual page 70

9 Adapting the appliance to the heating system
Caution:
b
Risk of damage due to freezing.
This function is not active if the value
"none" is set in the Menu A3
"hydraulic integration of the auxiliary heater"
for the auxiliary heater. In this case, an exter-
nal electric auxiliary heater cannot support
low temperature operation, nor is emergency
operation after a fault leading to permanent
deactivation or the emergency frost protec-
tion function possible.
Parts of the hydraulic system are not pro-
tected if the values "Hot water", "CH" or
"DHW+CH" (=external auxiliary heater)
have been set.
> You must ensure the hydraulic integra-
tion of the auxiliary heating system in
the Menu A3
Testing the external sensors
The hydraulic basic circuit given by you during commission-
ing determines the required sensors. The heat pump perma-
nently and automatically checks that all sensors are
installed and operational.
Protection from loss of heating water
An analogue pressure sensor monitors a possible water
shortage and switches the heat pump off if the water pres-
sure is below 50 kPa (0,5 bar), and on again if the water
pressure is above 70 kPa (0,7 bar).
Pump seizing and valve seizing protection
In order to prevent a circulation pump or all diverter valves
from jamming, the pump and the valves that have not been
operated for 24 hrs are switched on every day in succession
for a duration of approx. 20 seconds.
Protection against loss of brine (VWS only)
A pressure sensor monitors a possible brine shortage and
switches the heat pump off if the brine pressure falls below
20 kPa (0,2 bar) only once. The fault 91 is displayed in the
Error History.
The heat pump switches back on automatically when the
brine pressure rises above 40 kPa (0,4 bar).
If the brine pressure drops below 60 kPa (0,6 bar) for a
duration of more than one minute, a warning message
appears in Menu 1 (¬ operating instructions).
Underfloor protective circuit for all hydraulic devices
without buffer tank (hydraulics diagram 1 and 3)
If the heater flow temperature in the underfloor heater cir-
cuit which is measured by the sensor VF2 continuously
exceeds a value (max. CH temperature + compressor hys-
teresis + 2 K, factory setting : 52 °C) for more than 15 min-
utes, the heat pump switches itself off with the error mes-
sage 72 (¬ Ch. 11.5). When the heating flow temperature
falls below this value again and the error has been reset,
the heat pump switches back on.
70
(¬ Tab. 9.9)
.
(¬ Tab. 9.9)
You can change the maximum heater flow temperature
using the parameter "maximum heater circuit" via
vrDIALOG.
An incorporated limit thermostat is used as an additional
safeguard. It switches the external heating circuit pump off
when the set switch-off temperature is reached. During
direct heating mode, it switches off the internal unit perma-
nently.
Caution:
b
Risk of damage caused by too high a
switch-off value for the underfloor pro-
tective circuit.
Underfloor heating systems can be dam-
aged by excessive temperature caused by
too high a switch-off value for the under-
floor protective circuit.
> Set the value for the underfloor protec-
tive circuit to such a level that heated
floors cannot be damaged by excessive
temperatures.
Phase monitoring
The sequence (clockwise rotating field) and availability of all
phases of the 400 V -voltage supply are continuously moni-
tored during commissioning and consequent operation. If
the sequence is not correct or a phase fails, a fault switch-
off is applied to the heat pump in order to prevent damage
to the compressor.
In order to prevent this fault message during a shutdown by
the power supply operator (off period), the contact of the
control system signal receiver must be connected to termi-
nal 13 (Wiring diagram 2 and 3).
Freeze protection function for heat source
The outlet temperature of the heat source is constantly
measured. If this falls below a particular value,the compres-
sor temporarily switches off with the fault message 20 or 21
(¬ Ch. 11.4). If this fault occurs three times in succession,
the system shuts down (¬ Ch. 11.5).
You can set the value (factory setting -10 °C) for protection
against freezing for the geoTHERM VWS heat pumps in the
Installation Assistent A4 (¬ Ch. 9.7.4).
A value of +4 °C was set in the factory for the geoTHERM
VWW heat pumps. This value cannot be changed.
Installation instructions geoTHERM 0020051574_04