Service Manual
3Troubleshooting (continued)
Checking temperature sensors
The water heater temperature sensors (inlet water, outlet water, system water, and flue) are all resistance type devices. The following tables show the correct values for the sensors at various temperatures. Use an ohmmeter to read the resistance of the sensor at a known temperature. If the resistance of the sensor does not closely match its corresponding table, replace the sensor.
Table 3B - Inlet/Outlet System Sensor Resistance vs. Temperature
Temperature °F | Resistance Ω | Temperature °F | Resistance Ω |
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50 | 18,780 | 158 | 1,990 |
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68 | 12,263 | 176 | 1,458 |
86 | 8,194 | 194 | 1,084 |
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104 | 5,592 | 212 | 817 |
122 | 3,893 | ||
140 | 2,760 | ||
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Table 3C - Flue Temperature Sensor Resistance vs. Temperature |
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Temperature °F | Resistance Ω | Temperature °F | Resistance Ω |
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68 | 14,773 | 176 | 1,707 |
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86 | 9,804 | 194 | 1,266 |
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104 | 6,652 | 212 | 952 |
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122 | 4,607 | 230 | 726 |
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140 | 3,252 | 248 | 560 |
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158 | 2,337 | ||
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