High Altitude; Vi-Maintenance - Lennox LGH094U Unit Information

10-Combustion Air Inducer
The combustion air inducer is factory set and is not field ad­
justable. However, operation should be monitored to en­
sure proper operation. The combustion air inducer is used
to draw fresh air into the combustion chamber while simul­
taneously expelling exhaust gases. The inducer operates
throughout the heating cycle.
On a heating demand, the ignition control is energized by the
A55 Unit Controller. The ignition control then allows 30 to 40
seconds for the combustion air inducer to vent exhaust gas­
es from the burners. When the combustion air inducer is
purging the exhaust gases, the combustion air prove switch
is closing proving that the combustion air inducer is operating
before allowing the ignition control to energize. When the com­
bustion air prove switch is closed and the delay is over, the igni­
tion control activates the first stage operator of the gas valve
(low fire), the spark and the flame sensing electrode.
Sparking stops immediately after flame is sensed.

11-High Altitude

Units may be installed at altitudes up to 2000 feet (610 m)
above sea level without any modification. At altitudes
above 2000 feet (610 m), units must be derated to match
gas manifold pressures shown in table below.
NOTE — This is the only permissible derate for these units.
Altitude - ft. (m)
2001 - 3000 (610 - 915)
3001 - 4000 (915 - 1220)
4001 - 5000 (1220 - 1525)
5001 - 6000 (1525 - 1830)
6001 - 7000 (1830 - 2135)
B-Cooling System Service Checks
LGH units are factory charged and require no further ad­
justment; however, charge should be checked periodically.
See section III- CHARGING.

VI-MAINTENANCE

A-Filters
LGH units use four 20 x 25 x 2" pleated throw-away type
filters. Filters may be accessed through the economizer /
filter access door. Filters should be checked monthly (or
more frequently in severe use) and cleaned or replaced
regularly. Take note of the "AIR FLOW DIRECTION"
marking on the filter frame when re-installing.
NOTE-Filters must be U.L.C. certified or equivalent for
use in Canada.
B-Lubrication
All motors and blower wheels used in LGH units are pre­
lubricated; no further lubrication is required.
C-Supply Air Blower Wheel
Annually inspect supply air blower wheel for accumulated
dirt or dust. Turn off power before attempting to remove ac­
cess panel or to clean blower wheel.
Natural Gas LPG/Propane
in. w.g. kPa in. w.g.
3.6 0.90 10.2
3.5 0.87 9.9
3.4 0.85 9.6
3.3 0.82 9.4
3.2 0.80 9.1
D-Evaporator Coil
Inspect and clean coil at beginning of each season. Clean
using mild detergent or commercial coil cleanser. Check
condensate drain pan and line, if necessary. Flush coil and
condensate drain with water taking care not to get insula­
tion, filters and return air ducts wet. Check connecting
lines and coil for evidence of oil and refrigerant leaks.
E-Condenser Coil
Formed Coils -
Clean condenser coil annually with water and inspect
monthly during the cooling season.
Clean the all-aluminum coil by spraying the coil steadily and
kPa
uniformly from top to bottom. Do not exceed 900 psi or a
45_ angle; nozzle must be at least 12 inches from the coil
2.54
face. Take care not to fracture the braze between the fins
2.46
and refrigerant tubes. Reduce pressure and work cautious­
2.39
ly to prevent damage.
2.34
Slab Coils -
2.26
Clean condenser coil annually with detergent or commer­
cial coil cleaner and inspect monthly during the cooling
season. Check connecting lines and coil for evidence of
oil and refrigerant leaks.
NOTE-If owner complains of insufficient cooling, the
unit should be gauged and refrigerant charge checked.
Refer to Gauge Manifold Attachment and Charging sec­
tions in this manual.
F-Electrical
1- Check all wiring for loose connections.
2- Check for correct voltage at unit (unit operating).
3- Check amp-draw on both condenser fan motor and
blower motor.
Fan Motor Rating Plate ____ Actual ________
Indoor Blower Motor Rating Plate____ Actual____
4- Check crankcase heater temperatures to ensure they
are operating.
5- Check compressor sump thermistors to ensure they
are making contact with compressor shell (ultra high ef­
ficiency units only).
Page 59
WARNING
Electric shock hazard. Can cause
injury or death. Before attempting to
perform any service or maintenance,
turn the electrical power to unit OFF at
disconnect switch(es). Unit may have
multiple power supplies.