A.O. Smith 100 Series Service Handbook page 25

MCB - SECTION D
See Figure 12 on page 19 for location of this section on the MCB.
System configurations are set on the MCB circuit board with dip switches. SW1 dipswitch settings can be
viewed physically on the MCB. Settings can also be confirmed from the Control System's "Config Settings"
menu, see Control System Menus on page 44.
TABLE 4
Switch 1 Type of boiler application
VB or VW. This switch will change
the Operating Setpoint and the
Hi Limit settings range for hot
water supply (lower range) and
hydronic heating (higher range)
applications.
Switch 2 Number of trials for ignition
Switch 3 Not Used
Switch 4 Controlling Probe. This switch will
designate a remote temperature
probe or the boiler's factory
installed inlet temperature probe
as the "Controlling Probe."
Switch 5 Power Accessory Present
Switch 6 Low water cut off present
Switch 7 Low Gas Pressure Switch present On = Yes
Switch 8 Not Used
Switch 9 Not Used
Switch 10 Not Used
1 2 3 4 5 6 7 8 9 10
Figure 16
SW1 DIPSWITCHES
On = VB
Oper Setpnt
Setpnt Diff
Hi Limit
Hi Limit Dif
On = 3 trials
On = Remote
Temperature Probe or
Quad Thermistor Probe
On = Yes
On = Yes
Servicing should only be performed by a Qualified Service Agent
D
O P E N
SW1
105-215
1-50
135-235
20-50
Off = VW
Oper Setpnt 105-190
Setpnt Diff 1-50
Hi Limit 135-210
Hi Limit Dif 20-50
Off = 1 trial
Off = Inlet Temperature Probe
Off = No
Off = No
Off = No
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