A.O. Smith T-H2-DV User Manual

T-H2-DV/T-H2-OS Service Manual
Ver. 1.01
23
CONFIDENTIAL
10-5. Gas valve assembly
Unit Part #
Included
in #118
Takagi Part #
EKH6T (LP model)
Checkpoint
C,H1
EKH6U (NA model)
Function
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)
Failure events
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)
Effects on the water
heater if valves fails
1. Gas leak from the unit.
2. Excess carbon monoxide emissions. / No flames.
3. Lack of water temperature control.
Error codes when the
valves fails
111 121 510 701 711
Diagnostic
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.
Color/Number of wires
Blue - Light blue (MV) 78 to 100 VDC (during operation) / 0.9 to 1.3 kΩ
Blue - Green (SV
1
) 78 to 100 VDC (during operation) / 1.3 to 1.9 kΩ
Blue - Orange (SV
2
) 78 to 100 VDC (during operation) / 1.3 to 1.9 kΩ
Blue - Red (SV
3
)
78 to 100 VDC (during operation) / 0.9 to 1.7 kΩ
White - Red
(Proportional valve)
1.0 to 15 VDC (during operation) / 20 to 40 Ω
Proportional Valve
Proportional valve
Main gas valve
4-1/4" (108mm) 7/8" (22.2mm)
4-5/8" (119mm)
Solenoid valve
Gas
valve
3-5/8" (91.5mm)
1-3/8" (34mm)
2-5/8" (67mm)
EKH6T (for LP model) and
EKH6U
(NA) 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.

A.O. Smith T-H2-DV Specifications

General

Brand	A.O. Smith
Model	T-H2-DV
Category	Water Heater
Language	English