Service manual

T-M50 / T-M50 ASME Service manual
Ver. 1.05
23
CONFIDENTIAL
10-9. Water control valve (flow adjustment valve and bypass valve)
Unit Part # #418 AOS Part # EKH32 Checkpoint J
Function
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 T-M32. 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)
Failure event
1. Water leakage from valve.
2. The valve cannot modulate or make open / close positions.
Effects on the water
heater if water control
valve fails
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.
Error codes when Water
control valve fails
651
Diagnostic
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.
NOTE: Color/Number of wires and pictures are on the following page.