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SPECIFICATIONS
Inlet Size . . . . . . . . . . . . .
1
/
2
”
NPT
Outlet Size . . . . . . . . . . . .
1
/
2
”
inverted flare
Outlet Adapter Fittings . . . . . . . .
1
/
2
”
inverted flare x
3
/
8
”
NPT reducer
(furnished with controls noted below)
adapter.
1
/
2
”
x
1
/
2
”
inverted flare outlet
extension adapter
Mounting . . . . . . . . . . . . .
3
/
4
”
NPT, 4
1
/
2
”
bulb insertion length
Pilot Connection . . . . . . . . . .
1
/
4
”
compression fitting
37C SERIES GAS WATER HEATER CONTROLS
For Replacement of Standard Gas Water Heater Controls with
Built-In E.C.O. (Energy Cut Off)
FEATURES
• Automatic shut-off of main and pilot gas in the event of pilot failure.
• Pilot gas cock with safe lighting feature and filter.
• Temperature adjustment.
• Manifold pressure tap.
• Built-In E.C.O. (Energy Cut Off) non-cycling high limit.
37C73U-168
RESIDENTIAL WATER
HEATER CONTROLS
Replacement Gas Water Heater Controls
Model
Number
Replaces OEM
Model Number
Main Burner
Pilot
Temperature
Range
Shank Length
OEM
37C73U-171
37C73U-274
4.0
”
W.C. Nat. Gas
4.0
”
W.C. Nat. Gas
70° - 160°F
2
1
/
2
”
A. O. Smith
37C73U-173
37C73U-640
4.0
”
W.C. Nat. Gas
4.0
”
W.C. Nat. Gas
70° - 160°F
1
1
/
4
”
A. O. Smith
37C73U-172
37C73U-641
4.0
”
W.C. Nat. Gas
4.0
”
W.C. Nat. Gas
70° - 160°F
2
1
/
4
”
A. O. Smith
37C73U-174
37C73U-652
5.0
”
W.C. Nat. Gas
5.0
”
W.C. Nat. Gas
70° - 160°F
1
1
/
4
”
A. O. Smith
37C73U-170
37C73U-836
4
.
0
”
W.C. Nat. Gas
4.9
”
W.C. Nat. Gas
70° - 160°F
1
”
Rheem
Model
Number
Pressure Regulation
Temperature
Range
Shank
Length
Gas
Type
Main Burner
Pilot
37C73U-168
➀
3.5
”
W.C.
(A.O. Smith Style)
4.0
”
W.C. 70 to 160°F (21 to 71°C)
1
1
/
4
”
Natural Gas
(Right hand threads)
37C72U-185
➁
10.0
”
W.C.
10.0
”
W.C. 70 to 160°F (21 to 71°C)
1
1
/
4
”
L.P. Gas
(Left hand threads)
➀
Outlet adapter fittings included.
➁
Includes Left Hand outlet extension fittings:
1
/
2
”
LH x
1
/
2
”
LH inverted flare and
1
/
2
”
LH x
3
/
8
”
LH inverted flare
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