Conditions For Enabling The Heat Pump And Conditions For Automatic Starting Of The Heat Pump; Nothing Displayed On Programming Unit Display - Viessmann PLC VITOCAL 350-HT PRO Service Instructions For Contractors

Conditions for enabling the heat pump and conditions for automatic starting of the heat pump

If the "Enable heat pump" display is not active
(green), the heat pump cannot switch on.
1. Conditions for "Enable heat pump"
Power supply utility enable (in status display)
■
■ Switch on heat pump page (system on/off)
■ System ON/OFF switch on main page (in status
display)
■ On-site enable stage 1
No evaporator faults (alarm symbol)
■
Condenser not in manual mode and switched off
■
(hand symbol)
■ More than 3 minutes have elapsed since change-
over to re-cooling
More than 3 minutes have elapsed since commis-
■
sioning of control system
■ If the heat source is groundwater: No frost or
groundwater circuit flow alarm (alarm symbol)
■ At least 1 compressor is OK (no compressor
alarms, alarm symbol)
Refrigerant circuit is OK (no refrigerant circuit
■
alarms, alarm symbol)
■ Not all compressors have been switched off man-
ually (hand symbol)
■ System on/off on heat pump page (no other infor-
mation except heat pump enable is deactivated)
Note
Only when all conditions are met will the status dis-
play turn green (general status).
2. Conditions for starting the heat pump
Request for heating or cooling or for DHW
■
A certain minimum differential between set and
■
actual value

Nothing displayed on programming unit display

1. Check the voltage on the display.
2. Check Ethernet connection via switch.
3. Check network settings.
4. Replace the programming unit.
Troubleshooting
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