Installation and operating instruction
Gas condensing unit WTC-GB 15-B Compact and WTC-GB 25-B Compact
3 Product description
83309302 1/2018-05 La
15-196
3.3.3.2 Multifunction sensor VPT
The multifunction sensor determines and monitors:
volumetric flow,
system pressure,
flow temperature,
return temperature.
Volumetric flow
If the volumetric flow drops below 60 l/h, the appliance switches off (
W 10
),
(not in heating mode, when the condensing unit supplies the heating circuit dir-
ectly).
System pressure
If the system pressure drops below the value of parameter
2.2.7 minimum
system pressure warning
, a waring message is issued (
W 36
). If the system
pressure drops below 0.5 bar, the appliance switch off (
F 36
). If the pressure in-
creases above 0.5 bar, the appliance automatically restarts [ch. 6.6.2.2].
Differential temperature flow eSTB / flow VPT
If the difference between the flow temperature eSTB and the flow temperature VPT
exceeds a preset value, the appliance is switched off (
W 18
). If the warning occurs
several times in succession, the system goes to lockout (
F 18
).
Differential temperature flow VPT / return VPT
If the difference between flow and return temperature exceeds a specified value,
the appliance is switched off for at least 3 minutes. If the shutdown occurs several
times in succession, a warning is issued (
W 17
). When approaching this value, first
the pump capacity is increased and then the burner capacity is reduced.
Flow temperature increase VPT (gradient)
If the flow temperature increases too fast, the appliance is switched off (
W 19
). If
the warning occurs several times in succession, the system goes to lockout
(
F 19
). This function is only activated at a temperature of > 45 °C.
