RT-SVD03G-EN 83
RTRM/RTOM (Temperature Inputs)
Outdoor Air Sensor, Discharge Air Sensor, Coil Temperature Sensor
Terminals to read voltage:
Outdoor Air Sensor — RTRM J8-2, J8-1
Discharge Air Sensor — RTOM J4-5, J4-4
Coil Temperature Sensor 1 — RTRM J2-3, J2-4
Coil Temperature Sensor 2 — RTRM J9-2, J9-1
Note: These are RTRM, RTOM inputs only. Economizer inputs (MAS, RAS, OHS, RHS, CO
2
) are in
the ReliaTel Economizer inputs section.
Read DC voltage with the sensor attached. If voltage does not appear to be correct, read the
resistance of the circuit, then the sensor itself, to see if a problem exists in the sensor or the wiring.
With the sensor not attached there should be 5.00 VDC at the terminals listed above.
Service Tips:
The second sensor terminal listed above is common. All common terminals are grounded,
therefore one volt meter lead can be attached to ground for voltage tests. To check for induced
voltage, read AC voltage to ground from each sensor wire. Should be less than 1 VAC.
Problems to look for:
• Miswire / short / open
• Excessive resistance in circuit (corroded or loose connection)
• Sensor inaccurate (should be +- 2F of chart)
• Moisture in sensor (becomes accurate when dry)
• Induced voltage (high voltage wires in same conduit)
Table 31. Temperature Input
Temp
°F
Resistance
(K ohms) DC Volts
Temp
°F
Resistance
(K ohms) DC Volts
Temp
°F
Resistance
(K ohms) DC Volts
Temp
°F
Resistance
(K ohms) DC Volts
-40 345.684 4.856 -20 169.798 4.718 1 84.537 4.468 21 45.354 4.094
-39 333.237 4.851 -19 164.076 4.709 2 81.868 4.453 22 44.007 4.072
-38 321.274 4.845 -18 158.562 4.7 3 79.291 4.437 23 42.705 4.049
-37 309.777 4.84 -17 153.248 4.69 4 76.802 4.421 24 41.446 4.026
-36 298.724 4.834 -16 148.127 4.680 5 74.403 4.404 25 40.226 4.002
-35 288.097 4.828 -15 143.192 4.67 6 72.087 4.388 26 39.046 3.978
-34 277.879 4.823 -14 138.435 4.66 7 69.849 4.371 27 37.904 3.954
-33 268.053 4.816 -12 129.449 4.638 8 67.687 4.353 28 36.797 3.929
-32 258.603 4.81 -11 125.199 4.627 9 65.597 4.336 29 35.726 3.904
-31 249.523 4.804 -10 121.1 4.615 10 63.577 4.317 30 34.689 3.879
-30 240.81 4.797 -9 117.146 4.603 11 61.624 4.299 31 33.686 3.853
-29 232.425 4.79 -8 113.331 4.591 12 59.737 4.28 32 32.72 3.827
-28 224.355 4.783 -7 109.652 4.579 13 57.913 4.261 33 31.797 3.801
-27 216.59 4.776 -6 106.102 4.566 14 56.153 4.241 34 30.903 3.775
-26 209.114 4.768 -5 102.676 4.553 15 54.452 4.221 35 30.037 3.749
-25 201.918 4.76 -4 99.377 4.54 16 52.807 4.201 36 29.198 3.722
-24 194.991 4.752 -3 96.197 4.526 17 51.216 4.18 37 28.386 3.695
-23 188.32 4.744 -2 93.127 4.512 18 49.677 4.159 38 27.599 3.668
-22 181.904 4.736 -1 90.163 4.498 19 48.188 4.138 39 26.836 3.641
-21 175.738 4.727 0 87.301 4.483 20 46.748 4.116 40 26.097 3.613
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