Set Temperature Rise - Bryant 393AAV Installation, Start-Up, And Operating Instructions Manual

EXAMPLE: (0—2000 ft altitude)
Furnace rating plate input is 110,000 Btuh.
Btu heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 1050 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 70 sec
Gas rate = 103 cu ft/hr (from Table 8)
Btu heating input = 1050 X 103 = 108,150 Btuh
In this example, the orifice size and manifold pressure
adjustment is within ±2 percent of the furnace input rate.
TABLE 8—GAS RATE (CU FT/HR)
SIZE OF
SECONDS
TEST DIAL
FOR 1
1 2 5
REVOLUTION
cu ft cu ft cu ft
10 360 720 1800
11 327 655 1636
12 300 600 1500
13 277 555 1385
14 257 514 1286
15 240 480 1200
16 225 450 1125
17 212 424 1059
18 200 400 100
19 189 379 947
20 180 360 900
21 171 343 857
22 164 327 818
23 157 313 783
24 150 300 750
25 144 288 720
26 138 277 692
27 133 267 667
28 129 257 643
29 124 248 621
30 120 240 600
31 116 232 581
32 113 225 563
33
109 218 545
34 106 212 529
35 103 206 514
36 100 200 500
37 97 195 486
38 95 189 474
39 92 185 462
40 90 180 450
41 88 176 439
42 86 172 429
43 84 167 419
44 82 164 409
45 80 160 400
46 78 157 391
47 76 153 383
48 75 150 375
49 73 147 367

2. Set temperature rise.

Furnace must operate within range of temperature rise
specified on the furnace rating plate. Determine the air
temperature rise as follows.
a. Place duct thermometers in return and supply ducts as
near furnace as possible. Be sure supply-air thermom-
eters do not "see" heat exchangers so that radiant heat
will not affect thermometer readings. This is particularly
important with straight-run ducts.
b. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine
temperature rise.
c. Adjust air temperature rise by adjusting blower speed.
Increase blower speed to reduce temperature rise. De-
crease blower speed to increase temperature rise.
SIZE OF
SECONDS
TEST DIAL
FOR 1
1 2 5
REVOLUTION
cu ft cu ft cu ft
50 72 144 360
51 71 141 355
52 69 138 346
53 68 136 340
54 67 133 333
55 65 131 327
56 64 129 321
57 63 126 316
58 62 124 310
59 61 122 305
60 60 120 300
62 58 116 290
64 56 112 281
66 54 109 273
68 53 106 265
70 51 103 257
72
50 100 250
74 48 97 243
76 47 95 237
78 46 92 231
80 45 90 225
82 44 88 220
84 43 86 214
86 42 84 209
88 41 82 205
90 40 80 200
92 39 78 196
94 38 76 192
96 38 75 188
98 37 74 184
100 36 72 180
102 35 71 178
104 35 69 173
106 34 68 170
108 33 67 167
110 33 65 164
112 32 64 161
116 31 62 155
120 30 60 150
INLET
PRESSURE TAP
Fig. 13—Redundant Automatic Gas Control Valve
BURNER FLAME
MANIFOLD
WARNING: Disconnect the electrical power before
changing the blower motor speed tap. A failure to follow
this warning can cause personal injury.
d. To change blower motor speed selections for heating
mode, remove blower motor lead from control HEAT
terminal. (See Fig. 10.) Select desired blower motor
speed lead from 1 of the other terminals and relocate it
to HEAT terminal. See Table 9 for lead color identifi-
cation. Reconnect unused lead on SPARE terminal.
→TABLE 9—SPEED SELECTOR
COLOR
Black
Yellow (When
present)
Blue
Red
White
—16—
ON AND
OFF SWITCH
MANIFOLD
PRESSURE TAP
BURNER
Fig. 14—Burner Flame
FACTORY-
SPEED
ATTACHED TO
High
Medium-High
Medium-Low
Low
Common L2/COM
GAS
PRESSURE
REGULATOR
ADJUSTMENT
A95618
A89020
Cool
Spare
Heat
Spare