Start-up
Operation & Maintenance Manual 33
After the above procedure, allow unit to operate and confirm that everything is functional properly. Check to see
that chilled water leaving temperature agrees with the setpoint. Additionally, check all sensors to have valid
reading values through the HMI unit. The PLC uses 5 RTD thermistors to sense temperatures and the thermis-
tors include: Ambient, Condenser Refrigerant Leaving, Compressor Discharge, Chilled Water Entering, and
Chilled Water Leaving.
Temperature (
°
F)
Resistance(
Ω
)
Resistance(
Ω
)
Resistance(
Ω
)
Temperature(
°
F)
RTD Temperature Vs Resistance Table
Temperature(
°
F)
-328
-310
-292
-274
-256
-238
-220
-202
-184
-166
-148
-130
-112
-94
-76
-58
-40
-22
-4
14
32
18.49
50
68
86
104
122
140
158
176
194
212
230
248
266
284
302
320
338
356
374
382
410
103.90
428
446
464
482
500
518
536
554
572
590
608
626
644
662
680
698
716
734
752
-
-
183.17
22.80
107.79
186.32
27.08
111.67
190.45
31.32
115.54
194.07
35.53
119.40
197.69
39.71
123.24
201.29
43.87
127.07
204.88
48.00
130.89
208.45
52.11
134.70
212.02
56.19
138.50
215.57
60.25
142.29
219.12
64.30
146.06
222.65
68.33
149.82
226.17
72.33
153.58
229.67
76.33
157.31
233.17
80.31
161.04
236.65
84.27
164.76
240.13
88.22
168.46
243.59
92.16
172.16
-
-
247.04
96.09
175.84
100.00
179.51
Table 9