Electronic Components; Temperature Sensors - IBC EX Series Installation & Operating Manual

8.2 Electronic components

This section details the method for troubleshooting the non-standard electronic components on the
boiler.

8.2.1 Temperature sensors

The resistance of the temperature sensors varies inversely with temperature. To test, measure the
temperature of the sensed environment and compare with the value derived from the measurement
of the resistance (obtained by connecting a good quality test meter capable of measuring up to
5,000 kΩ (5,000,000Ω) at the controller end of the sensor lead).
To obtain a resistance reading, remove power to the boiler. For the supply water, return water, and
vent temperature sensors, remove the wire leads by disconnecting their respective Molex
connectors. Place multi-meter probes into the sensor's female Molex connector socket. Do not
apply voltage to the sensor as damage may result.
The supply water and vent temperature sensors each contain two separate circuits. Test each pair.
Both circuits must deliver accurate (although not necessarily identical) readings. Note that failures
may occur only within certain temperature ranges.
Temp. °F/°C
0 / -18
5 / -15
10 / -12
15 / -9
20 / -7
25 / -4
30 / -1
35 / 2
40 / 4
45 / 7
50 / 10
55 / 13
60 / 16
65 / 18
70 / 21
Resist.
Temp. °F/°C
Ω – Ohm
85,362
72,918
62,465
53,658
42,218
39,913
34,558
29,996
26,099
22,763
19,900
17,436
15,311
13,474
11,883
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Section: Troubleshooting
Resist.
Ω – Ohm
100 / 38
105 / 41
110 / 43
115 / 46
120 / 49
125 / 52
130 / 54
135 / 57
140 / 60
145 / 63
150 / 66
155 / 68
160 / 71
165 / 74
170 / 77
5,828
5,210
4,665
4,184
3,760
3,383
3,050
2,754
2,490
2,255
2,045
1,857
1,689
1,538
1,403