Table 5 Ð Rated Gas Inputs at Indicated Manifold Pressures
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| GAS SUPPLY PRESSURE | MANIFOLD | NATURAL GAS | PROPANE* | |||||||
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UNIT 48SS,SX | OF | Natural | Propane | (in. wg) | Ori®ce | Heating | Ori®ce | Heating | ||||
| ORIFICES |
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| Drill | Input | Drill | Input | |
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| Min | Max | Min | Max | Natural | Propane | Size | (Btuh)² | Size | (Btuh)² | |
018040, 024040, 030040 | 1 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.1 | 32 | 40,000 | 41 | 40,000 | |
024060, 030060, 036060, 042060 | 2 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.3 | 40 | 56,000 | 47 | 54,000 | |
030080, 036080, 042080, | 2 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.4 | 32 | 80,000 | 42 | 80,000 | |
048080, 060080 | ||||||||||||
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036100, 042100, 048100, 060100 | 2 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.7 | 30 | 95,000 | 40 | 95,000 | |
036120, 042120, 048120, 060120 | 3 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.5 | 32 | 120,000 | 42 | 115,000 | |
048140, 060140 | 3 | 4.0 | 13.0 | 4.0 | 13.0 | 3.5 | 3.4 | 31 | 136,000 | 40 | 133,000 | |
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*When a unit is converted to propane, different size ori®ces must be used. See separate
²Based on altitudes from sea level to 2000 ft above sea level. For altitudes above 2000 ft: reduce input rating 4% for each additional 1000 ft above 2000 ft. In Canada, from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10%.
NOTE: Unit size 018 is 48SS only.
Measure Gas Flow (Natural Gas Units) Ð Minor adjust- ment to the gas ¯ow can be made by changing the man- ifold pressure. The manifold pressure must be maintained between 3.4 and 3.6 in. wg. If larger adjustments are re- quired, change main burner ori®ces following the recom- mendations of national and local codes.
NOTE: All other appliances that use the same meter must be turned off when gas ¯ow is measured at the meter.
Proceed as follows:
1.Turn off gas supply to unit.
2.Remove pipe plug on manifold (see Fig. 24), then con- nect manometer at this point. Turn on gas to unit.
3.Record number of seconds for gas meter test dial to make one revolution.
4.Divide number of seconds in Step 3 into 3600 (number of seconds in one hour).
5.Multiply result of Step 4 by the number of cu ft shown for one revolution of test dial to obtain cu ft of gas ¯ow per hour.
6.Multiply result of Step 5 by Btu heating value of gas to obtain total measured input in Btuh. Compare this value with heating input shown in Table 5. (Consult the local gas supplier if the heating value of gas is not known.)
EXAMPLE: Assume that the size of test dial is 1 cu ft, one revolution takes 30 seconds, and the heating value of the gas is 1050 Btu/ft3. Proceed as follows:
1.30 seconds to complete one revolution.
2.3600 ÷ 30 = 120.
3.120 x 1 = 120 ft3 of gas ¯ow/hr.
4.120 x 1050 = 126,000 Btuh input.
If the desired gas input is 120,000 Btuh, only a minor change in the manifold pressure is required.
Observe manifold pressure and proceed as follows to ad- just gas input:
1.Remove cover screw over regulator adjustment screw on gas valve.
2.Turn regulator adjustment screw clockwise to increase gas input, or turn regulator adjustment screw counterclock- wise to decrease input. Manifold pressure must be be- tween 3.4 and 3.6 in. wg.
MANIFOLD | PIPE PLUG |
Fig. 24 Ð Burner Assembly
Unsafe operation of the unit may result if manifold pressure is outside this range. Personal injury or unit damage may result.
3.Replace cover screw cap on gas valve.
4.Turn off gas supply to unit. Remove manometer from pres- sure tap and replace pipe plug on gas valve. Turn on gas to unit and check for leaks.
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