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f.Look through sight glass in burner enclosure and check burner flame. Burner flame should be clear blue, almost transparent. (See Fig. 45.)
BURNER FLAME
BURNER
MANIFOLD
A89020
Fig. 45ÐBurner Flame
3. Verify natural gas input rate by clocking gas meter.
NOTE: Be sure all pressure tubing,
a.Calculate
UNITED STATES
At altitudes above 2000 ft, this furnace has been ap- proved for a 2% derate for each 1000 ft above sea level. See Table 10 for derate multiplier factor.
TABLE 10ÐALTITUDE DERATE MULTIPLIER FOR U.S.A.
ALTITUDE | % OF | DERATE MULTIPLIER |
(FT) | DERATE | FACTOR FOR U.S.A.* |
0Ð2000 | 0 | 1.00 |
2001Ð3000 | 4Ð6 | 0.95 |
3001Ð4000 | 6Ð8 | 0.93 |
4001Ð5000 | 8Ð10 | 0.91 |
5001Ð6000 | 10Ð12 | 0.89 |
6001Ð7000 | 12Ð14 | 0.87 |
7001Ð8000 | 14Ð16 | 0.85 |
8001Ð9000 | 16Ð18 | 0.83 |
9001Ð10,000 | 18Ð20 | 0.81 |
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* Derate multiplier factor is based on midpoint altitude for altitude range.
EXAMPLE:
100,000 Btuh input furnace installed at 4300 ft.
Furnace Input |
| Derate |
| Furnace Input Rate |
Rate at | X | Multiplier | = | at Installation |
Sea Level |
| Factor |
| Altitude |
100,000 | X | 0.91 | = | 91,000 |
CANADA
→At installation altitudes from 2000 to 4500 ft, this furnace must be derated 5% by an authorized Gas Conversion Station or Dealer. To determine correct input rate for altitude, see example above and use 0.95 as derate multiplier factor.
b.Turn off all other gas appliances and pilots.
c.Start furnace and let operate for 3 minutes.
d.Measure time (in sec) for gas meter test dial to complete 1 revolution.
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e.Refer to Table 11 for cu ft of gas per hr.
TABLE 11ÐGAS 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 | 1000 | 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 | 80 | 160 | 400 | 110 | 33 | 65 | 164 | |
46 | 78 | 157 | 391 | |||||
112 | 32 | 64 | 161 | |||||
47 | 76 | 153 | 383 | |||||
116 | 31 | 62 | 155 | |||||
48 | 75 | 150 | 375 | |||||
120 | 30 | 60 | 150 | |||||
49 | 73 | 147 | 367 | |||||
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f.Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft) using natural gas heating value from local gas utility/supplier.
EXAMPLE: (0Ð2000 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
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.
B.Set Temperature Rise
CAUTION: Temperature rise must be within limits specified on unit rating plate. Recommended operation is at midpoint of rise or above. Failure to follow this caution may result in condensing or overheating the heat ex- changers.
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
2.When thermometer readings stabilize, subtract