Lennox G26 series Installation Instructions Manual page 22

WHITE RODGERS 36E GAS VALVE
REGULATOR ADJUSTMENT SCREW LOCATION
_'_ REGULATOR
COVER SCREW
ADJUSTING
SCREW
FIGURE 35
Manifold Pressure Measurement & Adjustment
NOTE - Pressure test adaptor kit (10L34) is available from
Lennox to facilitate manifold pressure measurement.
1 - Connect test gauge to outlet tap on gas valve.
2 - Disconnect pressure sensing hose from gas valve and
plug hose by covering opening with tape or equivalent.
Leave barbed fitting on valve open to atmosphere.
See figure 36.
DIFFERENTIAL PRESSURE SWITCH CIRCUITRY
BURNER
BOX
BARB
PRESSURE
BOX
COMBUSTION SENSING
AIR PRESSURE _ HOSE
SENSING HOSE
GAS
VALVE
SENSING
HOSE
GAS
VALVE
AIRINDUCER
•PRESSURE
SWITCH
SENSING
HOSE
LEFT SIDE OF PRESSURE SWITCH = MORE NEGATIVE
RIGHT SIDE OF PRESSURE SWITCH = LESS NEGATIVE (Closer to Zero)
FIGURE 36
3 - Start unit and allow 5 minutes for unit to reach steady
state.
4 - Examine the burner flame. The flame should be stable
and should not lift from the burner. Natural gas should
bum blue. L.P./propane gas should bum mostly blue
with some orange streaks.
5 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to values given in
table 6.
NOTE - Shut unit off and remove manometer as soon as an
accurate reading has been obtained. Take care to replace
pressure tap plug.
NOTE - During this test procedure, the unit unit will be over-
firing:
• Operate unit only long enough to obtain accurate reading to
prevent oveilleaUng heat exchanger.
• Attempts to clock gas valve during this procedure will be
inaccurate. Measure gas flow rate only during nor-mal
unit operation.
6 - When test is complete remove obstruction from hose
and return hose to gas valve barbed fitting.
Gas Flow
To checkfor propergas flow tothe combustion chamber, de-
termine the Btu (kW) input from the unit rating plate. Divide
this input rating by the Btu (kW) per cubic foot (cubic meter)
of available gas. The result is the required number of cubic
feet (cubic meter) per hour. Determine the flow of gas
through the gas meter for two minutes and multiplyby 30 to
get the houdy flow of gas.
Unit does not need gas pressure adjustmentwhen operating
from 0 to 7500 feet (0 to 2248m). See table 6 for correctman-
ifold pressures for LP/propane and natural gases.
Natural to LP/Propane Changeover
A natural gas to LP/propane gas changeover kit is required
to convert unit. Refer to installation instructions supplied
with kit for conversion procedure.
Heat Anticipation Settings
Thermostat anticipator setting (if adjustable) should be set
according to amps listed on wiring diagram on unit.
Flame Rollout Switch
Factory set: No adjustment necessary.
Limit Control
Factory set: No adjustment necessary.
Pressure Switch
Factory set: No adjustment is necessary.
Fan Control
The fan-on delay of 45 seconds is not adjustable. The fan-
off delay (time that the blower operates after the heating
demand has been satisfied) can be adjusted by moving the
jumper on the SureLight
TM
integrated control. The unit is
shipped with a factory fan-off delay of 90 seconds. The fan-
off delay will affect comfort and is adjustable to satisfy indi-
vidual applications. See figure 37.
FAN-OFF TIME ADJUSTMENT
60sec, 90sec. 120sec. 180sec.
To adjust fan-off timing, flip dip switch to desired setting.
FIGURE 37
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