Control Sequence - Viessmann Vitotronic 200 Installation And Service Instructions For Contractors

Function description
Boiler water temperature control
Boiler protection function: Raising the return temperature via a shunt pump
For heating systems with distributor installed close to
■
the boiler
■ Conditions:
– 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 downstream.
Function
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
(specified by the coding card) is not being achieved.
The flow rate will be reduced via the mixers if the mini-
mum return temperature captured by temperature sen-
sor T1 is not achieved despite return temperature rais-
ing.
Return temperature raising in conjunction with
heating systems that are not connected with the
Vitotronic via LON
Plug A1 of the Vitotronic is used as a switching con-
sÖ
tact.
Boiler protection function: Return temperature control via shunt pump and 3-way mixing valve
For heating systems where downstream heating cir-
cuits cannot be controlled, e.g. older systems or com-
mercial nurseries.
Function
Temperature sensors T1 and T2 capture the return
temperature at different test points.

Control sequence

Boiler goes cold
The burner is started if the boiler water temperature
falls 2 K below the set boiler water temperature. The
burner starts its own monitoring program.
Note
The burner start may be delayed by a few minutes,
depending on the number of auxiliary circuits and the
combustion type.
110
(cont.)
Required parameter: "53:2" in the "General" group.
20 A1
20
N L
K
B
Fig. 46
A1 Closing of mixers
sÖ
Contactor relay, part no. 7814 681
A
Downstream heating circuit controller, switching
B
contact closed:
Signal for mixer CLOSE
The shunt pump is started via temperature sensor T2 if
the factory-selected minimum return temperature
(specified by the coding card) is not being achieved.
The flow rate will be reduced via the 3-way mixing
valve if the minimum return temperature captured by
temperature sensor T1 is not achieved despite return
temperature raising.
Boiler heats up
Single stage burner:
■
The burner is stopped if the boiler water temperature
rises 2 K above the set boiler water temperature.
■ Two-stage or modulating burner:
The burner is stopped if the boiler water temperature
rises above the set boiler water temperature by the
shutdown differential.
The shutdown differential is set at parameter "13" in
the "Boiler" group.
A
close close close
1 2 n