User`s manual

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22
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B. Gas Input
Check gas input and manifold pressure in “HIGH FIRE”
(W1 and W2 energized at gas valve) after unit start-up (see
Table 6). If adjustment is required, proceed as follows:
The rated gas inputs shown in Table 6 are for altitudes from
sea level up to 2000 ft above sea level. These inputs are
based on natural gas with a heating value of 1050 Btu/ft
3
at 0.65 specific gravity, or LP (liquid propane) gas with a
heating value of 2500 Btu/ft
3
at 1.5 specific gravity. For
elevations above 2000 ft, reduce input 4% for each 1000 ft
above sea level. When the gas supply being used has a differ-
ent heating value or specific gravity, refer to national and
local codes, or contact your distributor or branch to deter-
mine the required orifice size. Refer to Table 7 for the correct
orifice to use at high altitudes. Kits are available from your
distributor.
C. Adjusting 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 nat-
ural gas units. The manifold pressure must be measured to
determine the input of LP gas units.
NOTE: When observing manifold pressure on 2-stage units,
set unit for high fire.
Measuring Gas Flow at Meter Method — Natural Gas Units
Minor adjustment can be made by changing the manifold
pressure. The manifold pressure must be maintained
between 3.2 and 3.8 in. wg (when measured under high fire
on 2-stage units). If larger adjustments are required, change
main burner orifices following the recommendations 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 outlet of gas valve or on
manifold.
3. Connect manometer.
4. Turn on gas to unit.
5. Record number of seconds for gas-meter test dial to
make one revolution.
6. Divide number of seconds in Step 5 into 3600 (num-
ber of seconds in one hour).
7. Multiply result of Step 6 by the number of cubic ft
shown for one revolution of test dial to obtain cubic ft
of gas flow per hour.
8. Multiply result of Step 7 by Btu heating value of gas
to obtain total measured input in Btuh. Compare this
value with heating input shown in Table 1. (Consult
the local gas supplier if the heating value of gas is not
known.)
EXAMPLE: Assume that the size of test dial is one cubic ft,
one revolution takes 30 seconds and the heating value of the
gas is 1045 Btu/ft
3
.
Proceed as follows:
1. 30 seconds to complete one revolution
2. 3600
÷
30 = 120
3. 120 x 1 = 120 ft
3
of gas flow/hr
4. 120 x 1045 = 125,400 Btuh input
If the desired gas input is 125,000 Btuh, only a minor change
in the manifold pressure is required.
Observe manifold pressure and proceed as follows to adjust
gas input:
1. Remove cover screw over regulator adjustment screw
on gas valve. See Fig. 45.
2. Turn regulator adjustment screw clockwise to
increase gas input, or counterclockwise to decrease
input. Manifold pressure must be between 3.2 and
3.8 in. wg.
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit.
5. Remove manometer from pressure tap.
6. Replace pipe plug on gas valve or manifold.
7. Turn on gas to unit.
8. Check for leaks.
Table 6 — Rated Gas Inputs at Indicated Manifold Pressures
LEGEND
LP —
Liquid Propane
*Manifold pressure shown is for second stage of heat when energized.
†Maximum heating input based on altitudes from sea level up to 2000 ft above sea level.
For altitudes above 2000 ft, reduce input rating 4% for each 1000 ft above sea level. In
Canada, from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10%.
**When a 580D unit is converted to LP, the burners must be modified with accessory LP kit.
††580D090,102 only.
¶580D090-120 only.
CAUTION: These units are designed to consume
the rated gas inputs using the fixed orifices at speci-
fied manifold pressures as shown in Table 6.
DO NOT REDRILL THE ORIFICES UNDER ANY
CIRCUMSTANCES.
WARNING: Unsafe operation of the unit may
result if manifold pressure is outside this range. Per-
sonal injury or unit damage may result.
UNIT
NUMBER
OF
ORIFICES
GAS SUPPLY PRESSURE
(in. wg)
MANIFOLD
PRESSURE
(in. wg)*
NATURAL GAS
LIQUID
PROPANE**
Natural Propane Orifice
Drill
Size
Heating
Input
(Btuh)†
Orifice
Drill
Size
Heating
Input
(Btuh)†
Min Max Min Max Natural Propane
580D090-150
3 4.0 13.0 5.0 13.0 3.5 3.5 31 125,000†† 41 125,000††
4 4.0 13.0 5.0 13.0 3.5 3.5 31 180,000¶ 41 180,000¶
5 4.0 13.0 5.0 13.0 3.5 3.5 31 220,000 41 220,000
580D120, 150 5 4.0 13.0 5.0 13.0 3.5 3.5 30 250,000 38 250,000