Viessmann C3TB, Installation And Service Instructions For Contractors

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The heating circuit pump is switched ON and the 3-
way diverter valve is changed over, if the cylinder tem-
perature sensor captures a temperature lower than the
defaulted set value.
■ The cylinder loading pump is switched ON if the
boiler water temperature
≥
set cylinder temperature.
■ The burner is switched ON if the boiler water temper-
ature
≤
set cylinder temperature, and the cylinder
loading pump is switched ON when the required
boiler water temperature is reached.
DHW is regulated to the set temperature via the outlet
temperature sensor.
After the draw off process has ended the loading cylin-
der continues to be heated up, until the set DHW tem-
perature has been reached at the cylinder temperature
sensor.
The cylinder loading pump and the 3-way diverter
valve remain ON for a further 30 s.
Boosting DHW heating
This function is activated by specifying a second set
DHW temperature via coding address 58 in group
"DHW" and activating the fourth DHW phase for DHW
heating.
Heating is boosted during the periods selected in this
time phase.
Internal H1 extension (standard delivery)
Fig. 126
The internal extension is integrated into the control unit
casing. The internal cylinder loading pump is connec-
ted to relay output
sK .
An external safety valve can be linked to connection
gD .
Function description
Control unit
(cont.)
5775 636 GB
Functions