Dxm2 Service & Application Notes - Heat Controller DXM2 Application And Instruction Manual

Application, Operation, & Maintenance Manual
DXM2 Service & Application Notes
Pressure Switches
All pressure switches are designed to be normally closed
during normal operating conditions, and to open upon fault.
Condensate Sensor – The Condensate Sensor input will
fault upon sensing impedance less than 100,000 Ohms for
30 continuous seconds. The recommended design uses
a single wire terminated with a male 1/4" quick connect
located in the drain pan at desired trip level. Upon a high
condensate level the water will short between the air coil
and the quick connect producing a resistance less than
100,000 Ohms. Since condensate is free of impurities,
it has no conductivity. Only the impurities from the drain
pan and coil dust or dirt create the conductance. A second
ground wire with appropriate terminal to the drain pan can
be used with the control to replace the air coil ground path.
The Condensate Sensor can also essentially be any open
contact that closes upon a fault condition.
Thermistor Temperature Sensors – The thermistors used
with the DXM2 are NTC (negative temperature coeffi cient)
type. Table 7 shows the replacement part numbers for the
LT1 and LT2 thermistors. The sensors have a 1% tolerance
and follow the characteristics shown in Table 8. Table 9
shows the nominal resistance at any given temperature
and can be used for fi eld service reference. The sensor will
use a minimum of 24 awg wire.
Table 8: 1% Sensor Calibration Points
Minimum
Temp (°F) Resistance
(Ohm)
78.5 9523
77.5 9650
76.5 10035
75.5 10282
33.5 30975
32.5 31871
31.5 32653
30.5 33728
1.5 80624
0.5 83327
0.0 84564
Maximum Nominal
Resistance Resistance
(Ohm) (Ohm)
9715 9619
9843 9746
10236 10135
10489 10385
31598 31285
32512 32190
33310 32980
34406 34065
82244 81430
85002 84160
86264 85410
DXM2 UNIT CONTROLS
Table 9: Nominal resistance at
various temperatures
Resistance
Temp (ºC) Temp (ºF)
(kOhm)
-17.8 0.0 85.34
-17.5 0.5 84.00
-16.9 1.5 81.38
-12 10.4 61.70
-11 12.2 58.40
-10 14.0 55.30
-9 15.8 52.38
-8 17.6 49.64
-7 19.4 47.05
-6 21.2 44.61
-5 23.0 42.32
-4 24.8 40.15
-3 26.6 38.11
-2 28.4 36.18
-1 30.2 34.37
0 32.0 32.65
1 33.8 31.03
2 35.6 29.50
3 37.4 28.05
4 39.2 26.69
5 41.0 25.39
6 42.8 24.17
7 44.6 23.02
8 46.4 21.92
9 48.2 20.88
10 50.0 19.90
11 51.8 18.97
12 53.6 18.09
13 55.4 17.26
14 57.2 16.46
15 59.0 15.71
16 60.8 15.00
17 62.6 14.32
18 64.4 13.68
19 66.2 13.07
20 68.0 12.49
21 69.8 11.94
22 71.6 11.42
23 73.4 10.92
24 75.2 10.45
25 77.0 10.00
26 78.8 9.57
27 80.6 9.16
28 82.4 8.78
29 84.2 8.41
30 86.0 8.06
31 87.8 7.72
32 89.6 7.40
33 91.4 7.10
34 93.2 6.81
35 95.0 6.53
36 96.8 6.27
37 98.6 6.01
38 100.4 5.77
39 102.2 5.54
40 104.0 5.33
41 105.8 5.12
42 107.6 4.92
43 109.4 4.72
44 111.2 4.54
45 113.0 4.37
46 114.8 4.20
47 116.6 4.04
48 118.4 3.89
49 120.2 3.74
50 122.0 3.60
51 123.8 3.47
52 125.6 3.34
53 127.4 3.22
54 129.2 3.10
16
Heat Controller, Inc.
Resistance
Temp (ºC) Temp (ºF)
(kOhm)
55 131.0 2.99
56 132.8 2.88
57 134.6 2.77
58 136.4 2.67
59 138.2 2.58
60 140.0 2.49
61 141.8 2.40
62 143.6 2.32
63 145.4 2.23
64 147.2 2.16
65 149.0 2.08
66 150.8 2.01
67 152.6 1.94
68 154.4 1.88
69 156.2 1.81
70 158.0 1.75
71 159.8 1.69
72 161.6 1.64
73 163.4 1.58
74 165.2 1.53
75 167.0 1.48
76 168.8 1.43
77 170.6 1.39
78 172.4 1.34
79 174.2 1.30
80 176.0 1.26
81 177.8 1.22
82 179.6 1.18
83 181.4 1.14
84 183.2 1.10
85 185.0 1.07
86 186.8 1.04
87 188.6 1.01
88 190.4 0.97
89 192.2 0.94
90 194.0 0.92
91 195.8 0.89
92 197.6 0.86
93 199.4 0.84
94 201.2 0.81
95 203.0 0.79
96 204.8 0.76
97 206.6 0.74
98 208.4 0.72
99 210.2 0.70
100 212.0 0.68
101 213.8 0.66
102 215.6 0.64
103 217.4 0.62
104 219.2 0.60
105 221.0 0.59
106 222.8 0.57
107 224.6 0.55
108 226.4 0.54
109 228.2 0.52
110 230.0 0.51
111 231.8 0.50
112 233.6 0.48
113 235.4 0.47
114 237.2 0.46
115 239.0 0.44
116 240.8 0.43
117 242.6 0.42
118 244.4 0.41
119 246.2 0.40
120 248.0 0.39
121 249.8 0.38
122 251.6 0.37
123 253.4 0.36