Gas Valve Assembly - A.O. Smith T-D2-OS Service Manual

10-4. Gas valve assembly

Unit Part #
Function
Failure events
Effects on the water
heater if valves fails
Error codes when the
valves fails
Diagnostic
Color/Number of wires
Proportional Valve
Included
Takagi Part #
in #102
Opens and closes the gas pathways of the water heater (main and solenoid
gas valves)
Modulates the gas flow from the gas inlet (proportional gas valve)
1. Gas leak from the valves.
2. Unable to open/close (main and solenoid gas valves)
3. Unable to modulate the gas flow (proportional gas valve)
1. Gas leak from the unit.
2. Excess carbon monoxide emissions. / No flames.
3. Lack of water temperature control.
111
1. Visual inspection: connection/breakage of wires.
2. Listen for "clunk" sounds from the gas valves opening right after fan motor
initiates.
3. Check voltages and resistance of coils; proper range of values shown
below.
Blue - Light blue (MV)
Blue - Green (SV )
1
Blue - Orange (SV )
2
Blue - Red (SV )
3
White - Red
(Proportional valve)
T-D2-IN / T-D2-OS Service Manual
EKH6T (LP model)
EKK5K (NA model)
121
78 to 100 VDC (during operation) / 0.9 to 1.3 kΩ
78 to 100 VDC (during operation) / 1.3 to 1.9 kΩ
78 to 100 VDC (during operation) / 1.3 to 1.9 kΩ
78 to 100 VDC (during operation) / 0.9 to 1.7 kΩ
1.0 to 15 VDC (during operation) / 20 to 40 Ω
EKH6T (for LP model) and EKK5K (for NA model)
is an assembly of the gas manifold with gas valve
assembly. For safety reasons, these assemblies
should be installed in the unit as a whole set. The
diagram below shows the gas valve assembly.
20
CONFIDENTIAL
Ver. 1.00
Checkpoint
510 701
C,H1