Technical information

Control Overview—External Controls Connections
BMS Connections—External Changeover of Modulation to Staging [146]
Applicable for Vitotronic 300, GW2 (without communications)
External Changeover of Staged to Modulating Burner:
Dry contact to [146] plug.
Primary Consideration(s):
Dual fuel equipped systems.
Configurations:
Dry contact to [146] plug onto terminals 2 and 3.
Boiler coding 02:2 for modulating burner.
Contact open: Modulating operation.
Contact closed: Two stage operation.
Burner must be set to modulating.
Notes:
When burner type is scanned in the control, modulation appears.
This function is generally used in conjunction with a manufacturer
supplied burner panel which provides the switch over contact. Refer to
wiring schematic of panel for specific information regarding burner.
1 Boiler control.
2 Plug [146] used to interface
demand signal to control via
terminals 2 and 3. Open
contact removes staging burner
demand.
3 Field supplied relay and wiring
interconnections.
4 Field supplied relay to provide
burner changeover from
modulation to staged operation
when contact is closed
between terminals 2 and 3.
Note: Relays used to provide dry
contact demand to plug [146] is
controlled by local BMS or system
controller. The relay coil voltage
must be compatible with the
system that is controlling it. Some
examples of this are 24VAC,
120VAC and 24VDC.
IMPORTANT
Ensure that all field wiring conforms
to local codes and regulations.
Section 4.2
Section 4
2
1
146
R
143
146
4
3
1 2 3
Connection Overview
5346540 v1.0 09/2006 Technical information subject to change without notice
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