Weil-McLain -230 - Manual (Page 22)

Part number 550-100-029/0404
GAS
-
FIRED WATER BOILER SERIES
2 — Control Supplement
22
Troubleshooting
(continued)
Checking temperature sensors
1. The boiler temperature sensors (flue, outdoor, return water and supply
water) are all resistance-type devices.
2. The table at right shows the correct value for the sensor at various
temperatures.
3. Use the resistance values at 32°F, 60°F, 70°F and 212°F to measure the
sensor resistance at known temperatures (ice point, room temperature
and sea level boiling point). For ice point and boiling point, insert the
sensor in water at that temperature. Use an ohmmeter to read resistance
value.
4. To check whether the control module is correctly sensing temperature,
you can use a resistance decade box. Connect the decade box temporarily
in place of a sensor and use the control module Information mode (see
page 19 for details) to read the temperature. The temperature should be
close to the value corresponding to the input resistance.
Sensor resistance values
Temp
(°F)
Sensor ohms Temp
(°F)
Sensor ohms
Min Max Min Max
32 34265 37871 130 3698 4088
40 27834 30764 140 3043 3364
50 21630 23907 150 2517 2782
60 16944 18727 160 2091 2311
70 13372 14780 170 1744 1928
80 10629 11747 180 1461 1615
90 8504 9399 190 1229 1359
100 6847 7568 200 1038 1147
110 5545 6129 210 880 972
120 4517 4992 212 851 941
4
Instructions in this supplement are based
on factory default parameter settings.