Bradford White Magnum D75T125E3N Installation & Operation Manual page 53

Procedure for Checking Thermostat Sensors
Set the thermostat above water temperature (See temperature adjustment section) and observe system through one (1)
complete cycle. Make sure system operates as desired.
To check the upper sensor or lower sensor assembly, compare the resistance of the sensor terminals (blue leads for
upper sensor, yellow and black lead for lower sensor) as measured by an ohmmeter to the water temperature as
measured by an accurate thermometer. Thermistor resistance increases as the temperature decreases. The tables below
show the correct sensor resistance at various temperatures. Replace the sensor if the ohm reading in the chart does not
approximate the reading from the sensor at the temperature measured in the tank.
°F
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
°C
0
10
20
30
40
50
60
70
80
90
0 1 2
26109 25400 24712 24045
19906 19383 18876 18383
15314 14925 14548 14180
11884 11592 11308 11032
9299 9078 8862
7333 7165 7000
5827 5697 5570
4663 4562 4464
3758 3679 3602
3048 2986 2925
2488 2439 2391
2043 2004 1966
1688 1656 1625
1402 1376 1351
1170 1150 1129
982 965 949
828 814 801
0 1 2
32648 31026 29495 28049
19898 18968 18088 17253
12492 11942 11419 10922
8057 7722 7403
5327 5117 4917
3602 3468 3340
2488 2400 2316
1752 1693 1637
1256 1216 1177
916 888 861
In Degrees F
3 4 5
23399 22771 22163
17905 17440 16990
13823 13477 13140
10763 10502 10248
8653 8449 8250 8057
6839 6683 6531 6383
5446 5326 5208 5094
4368 4274 4183 4094
3527 3453 3382 3312
2866 2808 2752 3697
2344 2298 2253 2209
1928 1891 1856 1820
1595 1566 1567 1509
1327 1303 1280 1257
1110 1090 1071 1053
933 917 901 886
788 775 762 749
In Degrees C
3 4 5
26682 25389 24166
16461 15710 14998
10450 10000 9572
7099 6808 8532 6268
4726 4543 4368 4201
3217 3099 2986 2878
2235 2157 2083 2011
1582 1530 1480 1432
1140 1105 1070 1037
835 810 786 763
53
6 7 8 9
21573 21000 20445
16553 16128 15715
12812 12494 12185
10000 9760 9526
7869 7685 7507
6238 6098 5961
4982 4873 4767
4006 3922 3839
3244 3177 3112
3643 2590 2538
2166 2124 2083
1786 1753 1720
1481 1454 1427
1235 1213 1191
1035 1017 999
871 857 842
737 725 713
6 7 8 9
23010 21915 20879
14322 13680 13071
9165 8778 8409
6016 5775 5546
4042 3889 3742
2774 2675 2579
1942 1876 1813
1385 1340 1297
1005 974 944
741 719 698