Water Control Valve - A.O. Smith 710 ASME Service Manual

10-9. Water control valve (flow adjustment valve and bypass valve)
Unit Part #
Function
Failure event
Effects on the water
heater if water control
valve fails
Error codes when Water
control valve fails
Diagnostic
NOTE: Color/Number of wires and pictures are on the following page.
#423 AOS Part #
The water control valve in the water heater has three functions of water
control: flow adjustment, bypass, and two-way) This valve is exactly the
same as the water valve in the 910. Its functions are as follows:
1. Controls water flow to properly control the output hot water
temperature.
(The function of the flow adjustment valve)
2. Mixes the hot water from the heat exchanger and the cold water from
the water inlet to properly adjust the water heater's outlet water
temperature.
(The function of the bypass valve)
3. Stabilizes the water temperature in the heat exchanger, preventing
low-temperature corrosion caused by heat exchanger condensation.
(The function of the bypass valve)
4. Prevents water from flowing through the heat exchanger when water
heater is not in operation to protect the heat exchanger.
(The function of the two-way valve)
1. Water leakage from valve.
2. The valve cannot modulate or make open / close positions.
1. Water leakage from failed valve can damage other water heater
components.
2. Temperature fluctuations may occur in the hot water output of the water
heater, due to inability to modulate water flow.
3. Can cause water to still flow through the heat exchanger when the water
heater is not operating, possibly damaging the heat exchanger and causing
water leaks.
1. Visual inspection: connection / breakage of wires, motor drive locked due
to scale buildup, and /or water leakage.
2. Check voltages and resistance; proper range of values shown below.
710 / 710 ASME Service Manual
319143-086
651
23
CONFIDENTIAL
Ver. 1.00
Checkpoint J