Bryant 582A Series Installation, Start-Up And Service Instructions Manual page 16

HEATING NUMBER
INPUT OF
(Btuh*) ORIFICES
40,000
60,000
90,000
115,000
130,000
* When a unit is converted to propane, different size orifices must be used. See separate natural-
to-propane conversion kit instructions.
†Based 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 sea level. In Canada, from 2000 ft above sea
level to 4500 ft above sea level, derate the unit 10%.
C. Adjust Gas Input
The gas input to the unit is determined by measuring the
gas flow at the meter or by measuring the manifold pressure.
Measuring the gas flow at the meter is recommended for natu-
ral gas units. The manifold pressure must be measured to
determine the input of propane gas units.
Measure Gas Flow (Natural Gas Units)
Minor adjustment to the gas flow can be made by changing
the manifold pressure. The manifold pressure must be main-
tained between 3.4 and 3.6 in. wg. If larger adjustments are
required, change main burner orifices following the recom-
mendations of national and local codes.
NOTE: All other appliances that use the same meter must
be turned off when gas flow is measured at the meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (see Fig. 13) 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 flow
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 6. (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 32 seconds, and the heating value of the gas
3
is 1050 Btu/ft . Proceed as follows:
1. 32 seconds to complete one revolution.
2. 3600 ÷ 32 = 112.5.
3
3. 112.5 x 1 = 112.5 ft of gas flow/hr.
4. 112.5 x 1050 = 118,125 Btuh input.
If the desired gas input is 115,000 Btuh, only a minor change
in the manifold pressure is required.
Table 6 — Heating Inputs
GAS SUPPLY PRESSURE
Natural
Min
2 4.0
2 4.0
3 4.0
3 4.0
3 4.0
(in. wg)
Propane†
Max Min
13.0 4.0
13.0 4.0
13.0 4.0
13.0 4.0
13.0 4.0
Observe manifold pressure and proceed as follows to adjust
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 counter-
clockwise to decrease input. Manifold pressure must be
between 3.4 and 3.6 in. wg.
WARNING: Unsafe operation of the unit may result
if manifold pressure is outside this range. Personal in-
jury or unit damage may result.
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit. Remove manometer from
pressure tap and replace pipe plug on gas valve. Turn
on gas to unit and check for leaks.
—16—
MANIFOLD
PRESSURE
(in. wg)
Max Natural
13.0 3.5
13.0 3.5
13.0 3.5
13.0 3.5
13.0 3.5
Fig. 13 — Burner Assembly
Propane†
3.5
3.5
3.4
3.7
3.5