Gas Control & Thermal Well Testing & Replacement; Determine Water Temperature Inside Tank - Bradford White PDX250T6*FBN Service Manual

PDX Series
Stored water may be HOT when performing the following steps in this procedure.

Determine Water Temperature Inside Tank

Note: It is important to understand once the resistance for the thermal well is determined from page 25, water flow
through the heater should not occur. Prior to performing the steps below, turn off the cold water supply to the
water heater. This will prevent cold water flow into the tank affecting the resistance value of thermal well.
Step 1. Position gas control power switch to "OFF" position.
Step 2. Draw approximately 4 gallons of water from drain valve into a container and discard. Draw an
additional gallon and immediately measure water temperature using an accurate thermometer. It may
be necessary to open a hot water faucet to allow heater to drain.
Step 3. Using the chart below, determine correct resistance value for the water temperature from step 2.
Example: If temperature of water is 84°F, then the resistance through the sensor would be
8449 (see shaded area). NOTE: Sensor resistance increases as the temperature
falls.
°F
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
26
Take necessary precaution to prevent personal injury.
Sensor Resistance at Various Temperatures
0 1 2
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
814 801
Gas Control/Thermal Well Testing and
WARNING
In Degrees F
3 4 5
23399 22771
17905 17440
13823 13477
10763 10502
8449 8250
6683 6531
5326 5208
4274 4183
3453 3382
2808 2752
2298 2253
1891 1856
1566 1537
1303 1280
1090 1071
933 917 901
788 775 762
PDX SERVICE PROCEDURE VI
Replacement
6 7 8
22163 21573 21000
16990 16553 16128
13140 12812 12494
10248 1000 9760
8057 7869 7685
6383 6238 6098
5094 4982 4873
4094 4006 3922
3312 3244 3177
2697 2643 2590
2209 2166 2124
1820 1786 1753
1509 1481 1454
1257 1235 1213
1953 1035 1017
886 871 857
749 737 725
9
20445
15715
12185
9526
7507
5961
4767
3839
3112
2538
2083
1720
1427
1191
999
842
713
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