AERCO Modulex General Manual - Manual (Page 54)

APPENDIX A
A-2
TEMPERATURE SENSOR RESISTANCE CHART
TEMPERATURE
°F (°C)
RESISTANCE
(OHMS)
-76 (-60) 698961
-58 (-50) 33908
-40 (-40) 167835
-22 (-30) 88340
-4 (-20) 48487
14 (-10) 27648
32 (0) 16325
50 (10) 9952
68 (20) 6247
77 (25) 5000
86 (30) 4028
104 (40) 2662
122 (50) 1801
140 (60) 1244
158 (70) 876
176 (80) 628
194 (90) 458
212 (100) 339
230 (110) 255
248 (120) 194
The temperature sensors used in the Modulex boiler are 5k Ohm Negative Temperature
Coefficient (NTC). The relationship between temperature (°F or °C) and the nominal resistance
(Ohms) of the sensor are inversely proportional. That is; when temperature increases, sensor
resistance decreases and vice versa.
For Example:
At 77°F (25°C), the resistance is 5000 Ohms
At 194°F (90°C), the resistance is 458 Ohms