Bradford White UCG100H199 Installation & Operation Manual page 44

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 assembly, compare the resistance of the sensor terminals (yellow and black lead
for upper 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 0
40 26109
50 19906
60 15314
70 11884
80 9299
90 7333
100 5827
110 4663
120 3758
130 3048
140 2488
150 2043
160 1688
170 1402
180 1170
190 982
200 828
°C 0
0 32648
10 19898
20 12492
30 8057
40 5327
50 3602
60 2488
70 1752
80 1256
90 916
1 2 3
25400 24712 24045
19383 18876 18383
14925 14548 14180
11592 11308 11032
9078 8862 8653
7165 7000 6839
5697 5570 5446
4562 4464 4368
3679 3602 3527
2986 2925 2866
2439 2391 2344
2004 1966 1928
1656 1625 1595
1376 1351 1327
1150 1129 1110
965 949 933
814 801 788
1 2 3
31026 29495 28049
18968 18088 17253
11942 11419 10922
7722 7403 7099
5117 4917 4726
3468 3340 3217
2400 2316 2235
1693 1637 1582
1216 1177 1140
888 861 835
In Degrees F
4 5
23399 22771 22163
17905 17440 16990
13823 13477 13140
10763 10502 10248
8449 8250
6683 6531
5326 5208
4274 4183
3453 3382
2808 2752
2298 2253
1891 1856
1566 1567
1303 1280
1090 1071
917 901
775 762
In Degrees C
4 5
26682 25389 24166
16461 15710 14998
10450 10000
6808 8532
4543 4368
3099 2986
2157 2083
1530 1480
1105 1070
810 786
44
6 7 8
21573 21000
16553 16128
12812 12494
10000 9760
8057 7869 7685
6383 6238 6098
5094 4982 4873
4094 4006 3922
3312 3244 3177
3697 3643 2590
2209 2166 2124
1820 1786 1753
1509 1481 1454
1257 1235 1213
1053 1035 1017
886 871 857
749 737 725
6 7 8
23010 21915
14322 13680
9572 9165 8778
6268 6016 5775
4201 4042 3889
2878 2774 2675
2011 1942 1876
1432 1385 1340
1037 1005 974
763 741 719
9
20445
15715
12185
9526
7507
5961
4767
3839
3112
2538
2083
1720
1427
1191
999
842
713
9
20879
13071
8409
5546
3742
2579
1813
1297
944
698