A.O. Smith 110 Indoor Service Manual page 13

Check-
Part and Description
point
H1 Gas proportional valve
H2 Flow sensor
Air-fuel ratio rod
I
Flame rod
J Flow adjustment valve
110 Indoor / 110 Outdoor Service Manual
Color of wires
White - red
Red - Black
White - Black
Yellow - AFR rod
(Between AFR rod and
the computer board)
Orange - Flame rod
(Between flame rod and
the computer board)
Red - Black
13
CONFIDENTIAL
Normal range
1 to 15 VDC (during operation)
and
20 to 40 Ω
4 to 5.5 VDC
1 to 4 VDC (pulse)
1,080 pulse / min
(more than 18 Hz)
More than 0.5 μA
(during operation)
More than 1 μA
(during operation)
7 to 16 VDC and 0.09 to 0.2 kΩ
Ver. 1.01