Service Manual
3Troubleshooting
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.
It is important to note that the flue and outlet water sensors have two temperature sensing devices in one housing. These devices are designated as S1a/S1b, outlet sensor and S3a/S3b, flue sensor. Please reference the wiring diagram in the Armor Water Heater Installation and Operation Manual for correct terminal location.
Table 3B - Inlet 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 - Outlet Water Sensor Resistance vs. Temperature
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| S1a |
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| S1b |
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| (Wire Color - R/BK and Y) |
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| (Wire Color - G and Y) |
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| Temperature | Resistance | Temperature | Resistance | Temperature | Resistance | Temperature | Resistance |
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| 50 | 19,553 | 158 | 2,004 | 50 | 40,030 | 158 | 3,478 |
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| 68 | 12,690 | 176 | 1,464 | 68 | 25,030 | 176 | 2,492 |
| 86 | 8,406 | 194 | 1,084 | 86 | 16,090 | 194 | 1,816 |
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| 104 | 5,715 | 212 | 816 | 104 | 10,610 | 212 | 1,344 |
| 122 | 3,958 |
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| 122 | 7,166 |
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| 140 | 2,786 |
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| 140 | 4,943 |
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| Table 3D - Flue Sensor Resistance vs. Temperature |
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| S3a |
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| S3b |
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| (Wire Color - W/B and Y) |
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| (Wire Color - PR and Y) |
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| Temperature | Resistance | Temperature | Resistance | Temperature | Resistance | Temperature | Resistance |
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| 50 | 40,030 | 158 | 3,478 | 50 | 258,500 | 158 | 16,870 |
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| 68 | 25,030 | 176 | 2,492 | 68 | 125,500 | 176 | 12,000 |
| 86 | 16,090 | 194 | 1,816 | 86 | 80,220 | 194 | 8,674 |
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| 104 | 10,610 | 212 | 1,344 | 104 | 52,590 | 212 | 6,369 |
| 122 | 7,166 |
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| 122 | 35,270 |
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| 140 | 4,943 |
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| 140 | 24,160 |
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