Viessmann VITOTRONIC 100 GC1B Installation And Service Instructions Manual page 93

Vitotronic 100, GC1B Installation and Service
Boiler Water Temperature Control
Requirement:
– The boiler water flow rate must be able to be reduced
by at least 50%.
– With shunt pump:
Size the shunt pump to approx. 30% of the total
throughput.
– With 3-way mixing valve:
Size the boiler circuit pump at each boiler to approx.
110% of the total throughput.
Also affects the heating circuits.
Function
Single boiler systems and multi boiler systems with
a common shunt pump
Temperature sensors T1 and T2 capture the return
temperature at different test points.
The shunt pump is started via temperature sensor T2
if the factory-selected minimum return temperature
(defaulted by the boiler coding card) is not being
achieved.
The flow rate will be reduced via the mixing valve if the
minimum return temperature captured by temperature
sensor T1 is not achieved despite the return
temperature raising.
Single boiler systems with shunt pump and 3-way mixing
valve
Temperature sensors T1 and T2 capture the return
temperature at different test points.
The shunt pump is started via temperature sensor T2
if the factory-selected minimum return temperature
(defaulted by the boiler coding card) is not being
achieved.
The flow rate will be reduced via the 3-way mixing
valve if, in spite of the return temperature raising
facility, the minimum return temperature captured
by temperature sensor T1 is not achieved.
Multi boiler systems with shunt pumps for every boiler
Temperature sensors T1 and T2 capture the return
temperature at different test points.
The shunt pump is started via temperature sensor T2
if the factory-selected minimum return temperature
(defaulted by the boiler coding card) is not being
achieved.
If the minimum return temperature captured by
temperature sensor T1 is not achieved despite the
return temperature raising, the flow rate will be reduced
via the isolation valve. Where temperature sensor T1
cannot affect the isolation valves it must, instead,
regulate the downstream heating circuits.
(continued)
Multi boiler systems with boiler circuit pump and 3-way
mixing valve
Temperature sensor T1 records the return temperature.
The flow rate is proportionally reduced via the 3-way
mixing valve on the boilers if the factory-selected set
temperature (defaulted by the boiler coding card) is not
achieved.
When the set temperature is exceeded, the 3-way
mixing valve is opened and the flow rate is gradually
increased to 100%.
Multi boiler systems with boiler circuit pump, low loss
header and 3-way mixing valve
Temperature sensor T1 records the return temperature.
The flow rate is proportionally reduced via the 3-way
mixing valve on the boilers if the factory-selected set
temperature (defaulted by the boiler coding card) is not
achieved.
When the set temperature is exceeded, the 3-way
mixing valve is opened and the flow rate is gradually
increased to 100%.
Downstream heating circuits are hydraulically
separated.
The flow temperature is controlled by the temperature
sensor (cascade control unit) in the low loss header.
Connection in Heating Systems Without LON
Single Boiler System
Plug sÖA1 of the Vitotronic is used as switching
contact.
Required code: "4C:2" in category 1 "General"
Legend
Closing the mixing valves
sÖA1
Contactor relay
A
B Downstream heating circuit controller, switching
contact closed:
Signal for mixing valve "Close"
Function Description
93