Bypass Valve - A.O. Smith T-D2-OS Service Manual

10-10. Bypass valve

Unit Part #
Function
Failure events
Effects on the water heater
if bypass valve fails
Error codes when bypass
valve fails
Diagnostic
Color/Number of wires
The physical appearance of the bypass valve is similar to that of the flow adjustment valve.
However, their functions differ and cannot be substituted for each other.
#403 Takagi Part #
1. Mixes hot water from the heat exchanger with cold water from the
water inlet in order to modulate and control the water heater's outlet
water temperature.
2. Keeps the water temperature in the heat exchanger stable, preventing
low-temperature corrosion by reducing condensation buildup in heat
exchanger.
1. Water leakage from valve.
2. The valve cannot modulate properly.
1. Water leakage from failed valve can damage other water heater
components.
2. Temperature fluctuations in the hot water output.
1. Visual inspection: connection/breakage of wires.
2. Check voltages and resistance: proper range of values shown below.
Red - Black 7 to 16 VDC and 0.09 to 0.2 kΩ
26
CONFIDENTIAL
T-D2-IN / T-D2-OS Service Manual
EKK0U Checkpoint
N/A
Ver. 1.00
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