Installation manual

1083292-UIM-A-0114
36 Johnson Controls Unitary Products
Verify natural gas input rate by clocking meter.
1. Turn off all other gas appliances and pilots.
2. Run furnace for a minimum of 3 minutes in heating operation.
3. Measure time (in sec) for gas meter to complete 1 revolution and
note reading. The 2 cubic feet dial provides a more accurate mea-
surement of gas flow.
4. Refer to Table 14 for cubic feet of gas per hour.
5. Multiply cubic feet per hour by heating valve (BTU/ft
3
) to obtain
input.
If clocked rate does not match the input rate from the unit nameplate.
follow steps in next section to adjust the manifold pressure. Repeat
steps 2 - 5 until correct input is achieved.
HIGH ALTITUDE NATURAL GAS ORIFICE
CONVERSION
The National Fuel Gas Code requires that gas appliances installed
above 2,000 feet elevation have their inputs de-rated by 4% per 1,000
feet above sea level. The modulating furnaces automatically de-rate for
altitude by measuring the inducer blower pressure and using that to
determine if there is adequate air to support good combustion. If there
is not enough combustion air to properly support 100% of the furnace
nameplate input rate, the control will reduce the input to the point that
there will be good combustion.
If orifice hole appears damaged or it is suspected to have been
redrilled, check orifice hole with a numbered drill bit of correct size.
Never redrill an orifice. A burr-free and squarely aligned orifice hole
is essential for proper flame characteristics.
DO NOT bottom out gas valve regulator adjusting screw. This can
result in unregulated manifold pressure and result in excess over-
fire and heat exchanger failures.
NOTICE
Be sure to relight any gas appliances that were turned off at the
start of this input check.
Table 14: Gas Rate (CU FT/HR) at Full Input
Seconds For
1 Revolution
Size of Test Dial
Seconds For
1 Revolution
Size of Test Dial
1 Cu Ft 2 Cu Ft 5 Cu Ft 1 Cu Ft 2 Cu Ft 5 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