Carrier 58TUA - Manual (Page 16)

EXAMPLE:
Heat value 1040
Btu/cu ft specific gravity 0.62
Therefore; Orifice No. 45* with manifold pressure 3.7-in.
wc on high fire and 1.6-in. wc on low fire. * The furnace is
shipped with No. 44 orifices. Therefore, in this example all
main burner orifices must be changed and manifold pres­
sure must be adjusted.
(7.) Multiply gas rate (cubic ft/hr) X heating value (Btu/
cubic ft).
(7.) Proceed to item c. to adjust manifold pressure.
Table 12-^Gas Rate Cu Ft/Hr
SECONDS SIZE OF TEST DIAL SECONDS SIZE OF TEST DIAL
FOR 1 1 2 5 FOR 1 1 2 5
REVOLUTION
CU ft CU ft CU ft REVOLUTION CU ft CU ft cu ft
10 360 720 1800 50 72 144 360
11 327 655 1636 51 71 141 355
12 300 600 1500 52 69 138 346
13 277 555 1385 53 68 136 340
14 257 514 1286 54 67 133 333
15 240 480 1200 55 65 131 327
16 225 450 1125 56 64 129 321
17 212 424 1059 57 63 126 316
18 200 400 100 58 62 124 310
19 189 379 947 59 61 122 305
20 180 360 900 60 60 120 300
21 171 343 857 62 58 116 290
22 164 327 818 64 56 112 281
23 157 313 783 66 54 109 273
24 150 300 750 68 53 106 265
25 144 288 720 70 51 103 257
26 138 277 692 72 50 100 250
27 133 267 667 74 48 97 243
28 129 257 643 76 47 95 237
29 124 248 621 78 46 92 231
30 120 240 600 80 45 90 225
31 116 232 581 82 44 88 220
32 113 225 563 84 43 86 214
33 109 218 545 86 42 84 209
34 106 212 529 88 41 82 205
35 103 206 514 90 40 80 200
36 100 200 500 92 39 78 196
37 97 195 486 94 38 76 192
38 95 189 474 96 38 75 188
39 92 185 462 98 37 74 184
40 90 180 .450 100 36 72 180
41 88 176 439 102 35 71 178
42 86 172 429 104 35 69 173
43 84 167 419 106 34 68 170
44 82 164 409 108 33 67 167
45
46
47 80
78
76 160
157
153 400
391
383
110
112
116
120 33
32
31
30 65
64
62
60
164
161
155
48
49 75
73 150
147 375
367 150
b. Check gas input rate by clocking gas meter for low and
high fire.
(1.) Obtain average yearly heat value for local gas supply.
NOTE: Be sure heating value used for calculations is correct for
your altitude. Consult local gas utility for altitude adjustments of
gas heating value.
(2.) Check and verify orifice size in furnace. NEVER
ASSUME THE ORIFICE SIZE. ALWAYS CHECK
AND VERIFY.
(3.) Turn off all other gas appliances and pilots.
(4.) Turn SW2 to ON. Close R to W/Wl and jumper R to
W2 to start furnace in high fire and let run for 3
minutes.
(5.) Measure time (in sec) for gas meter to complete 1
revolution.
(6.) Refer to Table 12 for cubic ft of gas per hour.
EXAMPLE;
Btu heating input=Btu/cu ft X cu ft/hr
Heating value of gas 1070 Btu/cu ft
Time for 1 revolution of 2-cu/ft dial 72 sec
Gas rate= 100 X 1070=107,000 Btuh
(8.) Measured gas input should equal low and high fire gas
inputs on unit rating plate, ± 2 percent.
NOTE: High altitude—In the United States, gas input on rating
plate is for altitudes up to 2000 ft. Ratings for altitudes over 2000
ft MUST be reduced 4 percent for each 1000 ft above sea level. To
obtain the altitude-adjusted rating, adjust the manifold pressure,
item c., and replace the main burner orifices as needed. Refer to
National Fuel Gas Code Appendix F, Table F-4 for proper orifice
sizing at high altitudes.
NOTE: Canadian installations only—The Canadian ratings are
approved for altitudes up to 2000 ft for natural and propane gases.
High-altitude ratings are from 2000 ft to 4500 ft above sea level.
High-altitude rating includes a 10 percent derate as required by
Canadian standards.
(9.) Remove jumper R to W2 and repeat items 5 through 8
for low fire.
(10.) Proceed to item c. to adjust manifold pressure.
A CAUTION
DO NOT redrill burner orifices. Improper drilling (burrs, out
of round, etc.) can cause excessive burner operating noise and
misdirection of burner flames. This could result in flame
impingement on burners and heat exchanger surfaces, leading
to potential failures.
c. Adjust gas input.
(1.) Move SW2 to the ON position (See Fig. 13.) to lock
furnace in low-fire. Jumper R to W/Wl to call for low
gas heat.
(2.) Remove gas control regulator adjustment seal caps.
(See Fig. 13.)
(3.) Turn low-fire adjusting Screw (5/64-in. hex Allen
wrench) counterclockwise (out) to decrease input rate
or clockwise (in) to increase rate. When adjusting
input rate, DO NOT set manifold pressure less than
1.3-in. wc or more than 1.7-in. wc for natural gas. If
manifold pressure is outside this range, change main
burner orifices.
(4.) Turn SW2 to the OFF position after low-fire adjust­
ment.
(5.) Jumper R-to-W/Wl terminal connections on control to
keep furnace in high-fire adjustment.
(6.) Turn high-fire adjusting screw (5/64-in. hex Allen
wrench) counterclockwise (out) to decrease input rate
or clockwise (in) to increase rate. When adjusting
input rate, DO NOT set manifold pressure less than
3.2-in wc or more than 3.8-in. wc for natural gas. If
manifold pressure is outside this range, change main
burner orifices.
NOTE: If orifices are changed, both high fire and low fire input
rates must be readjusted, with manifold pressures within ranges
specified in items 3 and 6.
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