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PERFORMANCE DATA — 581C
ALTITUDE COMPENSATION* — 581C024-060
STANDARD UNIT
*As the height above sea level increases, there is less oxygen per cubic
foot of air. Therefore, heat input rate should be reduced at higher altitudes.
†Orifices available through your Bryant distributor.
ALTITUDE COMPENSATION* — 581C024-060
LOW NOx UNITS
*As the height above sea level increases, there is less oxygen per cubic
foot of air. Therefore, heat input rate should be reduced at higher altitudes.
†Orifices available through your Bryant distributor.
ALTITUDE DERATING FACTOR*
*Derating of the gas heating equipment to compensate for the effects of alti-
tude is always required. Orifice change is not required if the fuel heating
value (at sea level) is below the limits listed in the table at left. Derating con-
ditions must be 4% per thousand ft above 2000 ft. For example, at 4000 ft,
if the heating value of the gas exceeds 1000 Btu/ft
3
, the unit will require a
16% derating. For elevations above 6000 ft, the same formula applies. For
example, at 7000 ft, the unit will require a 28% derating of the maximum
heating value per the National Fuel Gas Code.
PERFECT HUMIDITY™ ADAPTIVE DEHUMIDIFICATION COIL PRESSURE DROP
ELEVATION
(ft)
50,000 BTUH NOMINAL INPUT
Natural Gas
Orifice Size†
Liquid Propane
Orifice Size†
0-2,000 43 49
2,000 44 50
3,000 44 50
4,000 44 50
5,000 45 51
6,000 45 51
7,000 46 51
8,000 47 52
9,000 47 52
10,000 48 52
11,000 49 53
12,000 50 54
13,000 51 55
14,000 52 56
ELEVATION
(ft)
60,000 AND 90,000 BTUH
NOMINAL INPUT
120,000 BTUH
NOMINAL INPUT
Natural Gas
Orifice Size†
Natural Gas
Orifice Size
0-2,000 38 32
2,000 40 33
3,000 41 35
4,000 42 36
5,000 43 37
6,000 43 38
7,000 44 39
8,000 45 41
9,000 46 42
10,000 47 43
11,000 48 44
12,000 49 44
13,000 50 46
14,000 51 47
ELEVATION
MAXIMUM HEATING VALUE
AT SEA LEVEL (Btu/ft
3
)
0-2000 1100
2001-3000 1050
3001-4000 1000
4001-5000 950
5001-6000 900
IMPORTANT: Local utility companies may be reducing heat content of gas at
altitudes above 2000 ft. If this is being done, changing spuds may not be
required.