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5784 568 - 03
Vitodens 100-W, B1HA series & B1KA Combi Installation/Service
Accessing
Electrical Connections
(continued)
Control Connections
Optional operating control - OpenTherm (OT)
What is OpenTherm (OT)?
The OpenTherm (OT) protocol is a point-to-point
communication system, which connects a boiler with a
room controller or other devices. The room temperature
feedback calculates a heating demand (water temperature
request) and transmits it to the boiler. The boiler will
adjust the heat input accordingly (low-high modulation).
Follow the installation instructions of the field supplied
operating controls.
GAS
PUMP
FAN
Boiler control base
%
B1HA:
For Viessmann DHW tanks: Tank temperature
sensor (plug on the cable harness outside the control
unit - red connectors labelled “5”).
Operation without DHW tank:
Set the set DHW temperature to”OFF”.
Note:
When connecting accessories observe the separate
installation instructions provided with them.
Legend
A
Viessmann outdoor temperature sensor (OTS) (field wiring)
B
OpenTherm (OT) 0-10V (field wiring)
C
Connection cable terminal
D
Power supply
E
Accessories 120VAC*
%
DHW tank temperature sensor or aquastat (field supplied)
(B1HA
only)
Refer to the Operating Instructions.
Legend
A
Room thermostat (24VAC)
B
Room thermostat (dry contact)
C
Switching relay
Room thermostat connection OpenTherm (OT)
24VAC thermostats require a
field supplied switching relay to
OT connection (ie Taco SR501
or Honeywell RA889A-1001)
OR
Connect Room Thermostat
(Dry Contact) to OT
connection
A
B
C
* When using the operating methods ‘operation without
room temperature thermostat’ or ‘weather compensated
operation without room temperature thermostat’ a jumper
must be installed on terminal 96, refer to page 64.
