Set Temperature Rise - Carrier 58MCB Installation, Start-Up, And Operating Instructions Manual

INLET
PRESSURE TAP
→
Fig. 46—Redundant Automatic Gas Valve
Fig. 47—Burner Orifice
Table 15—Altitude Derate Multiplier for U.S.A.
ALTITUDE % OF
(FT) DERATE
0—2000
2001—3000 4—6
3001—4000 6—8
4001—5000 8—10
5001—6000 10—12
6001—7000 12—14
7001—8000 14—16
8001—9000 16—18
9001—10,000 18—20
* Derate multiplier factor is based on midpoint altitude for altitude range.
ON AND
OFF SWITCH
GAS
PRESSURE
REGULATOR
ADJUSTMENT
BURNER
ENCLOSURE
REFERENCE
PRESSURE
TAP
MANIFOLD
PRESSURE TAP
BURNER
ORIFICE
DERATE MULTIPLIER
FACTOR
0 1.00
0.95
0.93
0.91
0.89
0.87
0.85
0.83
0.81
EXAMPLE: (0—2000 ft altitude)
Furnace input from rating plate is 100,000 Btuh.
Btu heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 975 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 70 sec
Gas rate = 103 cu ft/hr (from Table 16)
Btu heating input = 103 X 975 = 100,425 Btuh
In this example, the orifice size and manifold pressure
adjustment is within ±2 percent of the furnace input rate.

SET TEMPERATURE RISE

UNIT DAMAGE HAZARD
Failure to follow this caution may result in overheating the
heat exchangers or condensing flue gases in heat exchanger
A95622
areas not designed for condensate.
Temperature rise must be within limits specified on unit
rating plate. Recommended operation is at midpoint of rise
range or slightly above.
Determine and adjust air temperature rise as follows:
1. Place thermometers in return and supply ducts as close to
furnace as possible. Be sure thermometers do not see heat
exchanger so that radiant heat does not affect readings. This
practice is particularly important with straight-run ducts.
Table 16—Gas Rate (Cu Ft/Hr)
SECONDS
FOR 1
REVOLUTION
10
11
12
13
A93059
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
51
SIZE OF TEST DIAL SECONDS
FOR 1
1 2 5
REVOLUTION
cu ft cu ft cu ft
360 720 1800 50
327 655 1636 51
300 600 1500 52
277 555 1385 53
257 514 1286 54
240 480 1200 55
225 450 1125 56
212 424 1059 57
200 400 1000 58
189 379 947 59
180 360 900 60
171 343 857 62
164 327 818 64
157 313 783 66
150 300 750 68
144 288 720 70
138 277 692 72
133 267 667 74
129 257 643 76
124 248 621 78
120 240 600 80
116 232 581 82
113 225 563 84
109 218 545 86
106 212 529 88
103 206 514 90
100 200 500 92
97 195 486 94
95 189 474 96
92 185 462 98
90 180 450 100
88 176 439 102
86 172 429 104
84 167 419 106
82 164 409 108
80 160 400 110
78 157 391 112
76 153 383 116
75 150 375 120
73 147 367 124
SIZE OF TEST DIAL
1 2 5
cu ft cu ft cu ft
72 144 360
71 141 355
69 138 346
68 136 340
67 133 333
65 131 327
64 129 321
63 126 316
62 124 310
61 122 305
60 120 300
58 116 290
56 112 281
54 109 273
53 106 265
51 103 257
50 100 250
48 97 243
47 95 237
46 92 231
45 90 225
44 88 220
43 86 214
42 84 209
41 82 205
40 80 200
39 78 196
38 76 192
38 75 188
37 74 184
36 72 180
35 71 178
35 69 173
34 68 170
33 67 167
33 65 164
32 64 161
31 62 155
30 60 150
29 58 145