Lennox GCS16R-411-100

Page 32
ON
OFF
MANIFOLD
PRESSURE
OUTLET
MANIFOLD
PRESSURE AD
JUSTMENT
SCREW
GAS VALVE
FIGURE 30
GAS VALVE
MANIFOLD ADJUSTMENT
1- Connect a test gauge to the outlet pressure tap on the
gas valve. Start the unit and allow five minutes for the
unit to reach steady state.
2- While waiting for the unit to stabilize, notice the flame.
The flame should be stable without flashback and
should not lift from the burner head. Natural gas
should burn blue. L.P. gas should burn mostly blue
with some orange streaks.
3- After allowing the unit to stabilize for five minutes, re
cord the manifold pressure and compare to the values
given in table 14.
CAUTION-Disconnect heating demand as soon as
an accurate reading has been obtained.
F-Proper Gas Flow
To check for proper gas flow to combustion chamber, de
termine Btuh input from the unit rating plate or table 15.
Divide this input rating by the Btuh per cubic foot of avail
able gas. Result is the number of cubic feet per hour re
quired. Determine the flow of gas through gas meter for
two minutes and multiply by 30 to get the hourly flow of gas
to the burner.
TABLE 15
Unit Input
Input
(cubic feet)
50,000 Btuh
75,000 Btuh
100,000 Btuh
125,000 Btuh
Unit
GCS16(H)50
GCS16-75
GCS16-100
GCS16-125
Unit Output
40,000 Btuh
60,000 Btuh
80,000 Btuh
100,000 Btuh
G-High Altitude Derate
The maximum input may be reduced by up to 24 percent
on A.G.A. units equipped with adjustable gas valves and
operating on natural gas. See table 16.
Follow the derate instructions shown below. If high altitude
conditions are present, also follow the instruction in table
16.
To reduce maximum input (derate instructions):
1- Check manifold pressure at the gas valve pressure
tap.
2- To reduce maximum input, turn regulator adjusting
screw (figure 17) counterclockwise.
3- Re-check manifold pressure.
TABLE 16
If the heating value of the gas does not exceed the values listed in
this table, derating of unit is not required. Should the heating value
of the gas exceed the table values, or if the elevation is greater
than 6,000 ft. above sea level, it will be necessary to derate the
unit. Lennox requires that derate conditions be 4 percent per thou
sand feet above sea level. Thus at an altitude of 4000 feet, if the
heating value of the gas exceeds 1000 Btu/cubic ft., the unit will
require a 16 percent derate.
HIGH ALTITUDE DERATE
Elevation Above
Sea Level (Feet)
Maximum Heating
Value (Btu/cubic ft.
5001-6000
4001-5000
3001-4000
2001-3000
Sea Level - 2000
900
950
1000
1050
1100
H-Inshot Burner
When servicing the burner, do not remove the bolts behind
slots in the burner plate (see figure 32).