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

T-H2-DV/T-H2-OS Service Manual
Ver. 1.01
32
CONFIDENTIAL
10-13. Exhaust thermistor
Unit Part # #706 Takagi Part # EKH6E Checkpoint K1
Function
Measure the exhaust temperatures in the exhaust chamber.
Failure events
Unable to measure exhaust temperature in the exhaust chamber properly.
Effects on the water heater
if exhaust thermistor fails
If the thermistors fail open or short, error code appears before starting
operation. If resistance values are just off, the “341” error codes will
display.
Error codes when exhaust
thermistor fails
341 (T-H2-DV only)
Diagnostic
1. Visual inspection: connection/breakage of wires and/or debris on
impeller.
2. Check voltages: proper range of values shown below.
Color/Number of wires White - White
68˚F (20°C) 12.6 to 13.4 kΩ
122˚F (50°C) 4.3 to 4.5 kΩ
176˚F (80°C) 1.7 to 1.8 kΩ
(see table below for more resistance values)
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
20 40 60 80 100 120 140 160 180 200 220
Temperature / ºF
Resisitance / kΩ
Resistance values of thermistors as a function of temperature
(Exhaust thermistor) 52
Black
Insulating

A.O. Smith T-H2-DV Specifications

General

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