Viessmann Vitotronic 200 Installation And Service Instructions Manual page 68

Function description
Boiler water temperature control
Raising the return temperature via a shunt pump
For heating systems with distributor
installed close to the boiler
Precondition:
The boiler water flow rate must be
able to be reduced by at least
50 %
Shunt pump sized to approx. 30 %
of the total throughput
Also affects the heating circuits of a
Vitotronic 200-H installed down-
stream
Function
The temperature sensors T1 and T2
capture the return temperature at dif-
ferent test points.
The shunt pump is started via tem-
perature 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
mixer if, in spite of the raising of the
return temperature the minimum
return temperature, captured by tem-
perature sensor T1, is not achieved.
Raising the return temperature via shunt pump and three-way mixer
For heating systems where down-
stream heating circuits cannot be con-
trolled, e.g. older heating systems or
commercial nurseries.
68
(cont.)
Return temperature raising in con-
junction with heating systems that
are not connected with the
Vitotronic via LON
Plug sÖ A1 of the Vitotronic is used
as switching contact.
Required coding: "4C:2"
sÖ A1 Closing the mixers
A Contactor relay, part no. 7814
681
B Downstream heating circuit
controller, contact closed:
Signal for mixer "Close"
Function
The temperature sensors T1 and T2
capture the return temperature at dif-
ferent test points.