Freeze Protection Thermostat - A.O. Smith 710 ASME Service Manual

10-18. Freeze protection thermostat

Unit Part #
Function
Failure event
Effects on the water
heater if the freeze
protection thermostat
fails
Error codes when the
freeze protection
thermostat fails
Diagnostic
Color / Number of wires
Activation and deactivation temperature of the 710 models freeze protection system
ON mode: 36.5˚F (+6.3˚F -2.7˚F)
OFF mode: above 46.4˚F
#117 AOS Part #
Temperature detecting device which prevents the pipes within the water
heater from freezing.
36.5˚F (2.5˚C) inside the water heater, power is supplied to the electric
heaters to prevent the water heater from freezing.
1. ON-failure (Always senses freezing temperatures, regardless of actual
temperature).
2. OFF-failure (Never senses freezing temperatures).
1. The freeze protection heaters will always be ON, causing heat damage to
components inside the water heater.
2. The freeze protection heaters will never be able to turn on, even under
freezing temperatures, causing freeze damage to the water heater.
1. Visual inspection: connection / breakage of wires and/or the body has
been broken.
2. Check resistance and voltage: proper range of values shown below.
Black - Black ON mode: 90 to 110 VAC and less than 1 Ω
(itself) OFF mode: less than 1 VAC and more than 1 MΩ
2.5˚C (+3.5˚C -1.0˚C)
above 8 ˚C
710 / 710 ASME Service Manual
319143-185
When this device detects temperatures below
N/A
7 / 8 " ( 2 2 .2 m m )
33
CONFIDENTIAL
Ver. 1.00
Checkpoint L
1 / 4 " ( 5 .7 m m )