Viessmann SCU345 Manual page 54

∆T function
ODTFT
∆T function
Selection: ON / OFF
Factory setting: OFF
The optional ∆T function uses the senors S3 (heat
source) and S5 (heat sink) to switch the adjustable
relay.
Note
The optional ∆T function is available in ar-
rangement 1 and 3 only.
ODTFT / DT4O
Switch-on difference
Adjustment range: 1.0 ... 50.0 K [2.0 ... 90.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 6.0 K [12.0 °Ra]
54
ODTFT / DT4F
Switch-off difference
Adjustment range: 0.5 ... 49.5 K [1.0 ... 89.0 °Ra]
in steps of 0.5 K [1.0 °Ra]
Factory setting: 4.0 K [8.0 °Ra]
The switch-on and switch-off differences DT4O and
DT4F are valid for this function.
Minimum limitation for the ∆T function
DT4 / TH10
Switch-on temperature
Adjustment range: 0.0 ... 95.0 °C [30.0 ... 200.0 °F]
in steps of 0.5 °C [1.0 °F]
Factory setting: 65.0 °C [150.0 °F]
DT4 / TH1F
Switch-off temperature
Adjustment range: 0.0 ... 95.0 °C [30.0 ... 200.0 °F]
in steps of 0.5 °C [1.0 °F]
Factory setting: 60.0 °C [140.0 °F]
If the adjusted value TH1O is exceeded, the relay
will be switched on. If the temperature falls below the
adjusted value TH1F, the relay will be switched off.
Maximum limitation for the ∆T function
DT4 / TH2O
Switch-on temperature
Adjustment range: 0.0 ... 95.0 °C [30.0 ... 200.0 °F]
in steps of 0.5 °C [1.0 °F]
Factory setting: 45.0 °C [120.0 °F]
DT4 / TH2F
Switch-off temperature
Adjustment range: 0.0 ... 95.0 °C [30.0 ... 200.0 °F]
in steps of 0.5 °C [1.0 °F]
Factory setting: 50.0 °C [125.0 °F]
If the temperature falls below the adjusted value
TH2O, the relay will be switched on. If the tempera-
ture exceeds the adjusted value TH2F, the relay will
be switched off.