Carrier 58MVB Installation, Start-Up, And Operating Instructions Manual page 55

Table 16—Altitude Derate Multiplier for U.S.A.
ALTITUDE % OF
(FT) DERATE
0—2000 0
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.
EXAMPLE: 100,000 BTUH HIGH-HEAT INPUT FURNACE
INSTALLED AT 4300 FT.
Derate
Furnace Input Rate
X Multiplier
at Sea Level
Factor
100,000 X
CANADA
At installation altitudes from 2000 to 4500 ft, this furnace
must be derated 5 percent by an authorized Gas Conversion
Station or Dealer. To determine correct input rate for
altitude, see example above and use 0.95 as derate multi-
plier factor.
b. Reinstall burner box cover.
NOTE: Clocking gas input rate MUST always be performed with
the burner box cover INSTALLED.
c. Check that gas valve adjustment caps are in place for
proper input to be clocked.
d. Obtain average heat value (at altitude) from local gas
supplier.
NOTE: Be sure heating value of gas used for calculations is
correct for your altitude. Consult local gas utility for altitude
adjustment of gas heating value.
e. Check and verify orifice size in furnace. NEVER ASSUME
THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.
f. Turn off all other gas appliances and pilots.
g. Move setup switch SW1-2 to ON position. (See Fig. 37.)
This keeps furnace locked in low-heat operation.
h. Jumper R to W/W1.
i. Let furnace run for 3 minutes in low-heat operation.
j. Measure time (in sec) for gas meter to complete 1 revolu-
tion. Note reading.
k. Refer to Table 17 for cubic ft of gas per hr.
l. Multiply gas rate cu ft/hr by heating value (Btu/cu ft).
m. Move setup switch SW1-2 to OFF position and jumper R
and W/W1 and W2 thermostat connections. (See Fig. 37.)
This keeps furnace locked in high-heat operation. Repeat
items i through l for high-heat operation.
DERATE MULTIPLIER
FACTOR FOR U.S.A.*
1.00
0.95
0.93
0.91
0.89
0.87
0.85
0.83
0.81
Furnace Input Rate
= at Installation
Altitude
0.91 = 91,000
Table 17—Gas Rate Cu Ft/Hr
SIZE OF TEST DIAL
SECONDS
FOR 1
1 2
REVOLUTION
cu ft cu ft
10 360 720
11 327 655
12 300 600
13 277 555
14 257 514
15 240 480
16 225 450
17 212 424
18 200 400
19 189 379
20 180 360
21 171 343
22 164 327
23 157 313
24 150 300
25 144 288
26 138 277
27 133 267
28 129 257
29 124 248
30 120 240
31 116 232
32 113 225
33 109 218
34 106 212
35 103 206
36 100 200
37 97 195
38 95 189
39 92 185
40 90 180
41 88 176
42 86 172
43 84 167
44 82 164
45 80 160
46 78 157
47 76 153
48 75 150
49 73 147
EXAMPLE: (High-heat operation at 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 17)
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.
NOTE: Measured gas inputs (high heat and low heat) must be
within ±2 percent of that stated on furnace rating plate when
installed at sea level or derated per that stated above when installed
at higher altitudes.
n. Remove jumper across R, W/W1, and W2 thermostat
connections to terminate call for heat.
55
SIZE OF TEST DIAL
SECONDS
FOR 1
5 1 2
REVOLUTION
cu ft cu ft cu ft
1800 50 72 144
1636 51 71 141
1500 52 69 138
1385 53 68 136
1286 54 67 133
1200 55 65 131
1125 56 64 129
1059 57 63 126
1000 58 62 124
947 59 61 122
900 60 60 120
857 62 58 116
818 64 56 112
783 66 54 109
750 68 53 106
720 70 51 103
692 72 50 100
667 74 48 97
643 76 47 95
621 78 46 92
600 80 45 90
581 82 44 88
563 84 43 86
545 86 42 84
529 88 41 82
514 90 40 80
500 92 39 78
486 94 38 76
474 96 38 75
462 98 37 74
450 100 36 72
439 102 35 71
429 104 35 69
419 106 34 68
409 108 33 67
400
110 33 65
391
112 32 64
383
116 31 62
375
120 30 60
367
5
cu ft
360
355
346
340
333
327
321
316
310
305
300
290
281
273
265
257
250
243
237
231
225
220
214
209
205
200
196
192
188
184
180
178
173
170
167
164
161
155
150