Surge Box - A.O. Smith 110 Indoor Service Manual

10-18. Surge box

Unit Part #
Function
Failure events
Effects on the water
heater if the Surge box
fails
Error codes when the
Surge box fails
Diagnostic
Color/Number of wires
Fuse: 5 A
Surge absorber A: 220 V
#703 AOS Part #
Protects the unit from high voltage and/or high electric current caused by
lightning.
There are 2 types of surge absorbers in the water heater. Surge absorber A is
activated by voltage higher than 220V, the other one is activated by voltage
higher than 680 V.
1. Open-failure of the absorber and/or fuse.
2. Short-failure of the absorber.
1. Unable to protect the computer board if high voltage gets applied to the
unit. The computer board can short out, stopping all operations.
2. The unit cannot operate because the absorber shorted out, causing the
fuse to break open.
1.Visual inspection:
connection/breakage of wires.
2. Check resistance and voltage: proper range of values shown below.
White-Black
Surge absorber B: 680 V
110 Indoor / 110 Outdoor Service Manual
319143-168
N/A
burn marks
108 to 132 VAC
34
CONFIDENTIAL
Ver. 1.01
Checkpoint
on components
A2,A3
and/or