Lennox LGA Series Unit Information page 39

7-Inshot Burner
Burners are factory set for maximum air and cannot be ad-
justed. Always operate unit with access panel in place. A peep
hole is furnished in the heating access panel for flame viewing.
Natural gas should burn basically blue with some clear
streaks. L.P. gas should burn mostly blue with some clear yel-
low streaks.
Figure 29 shows how to remove burner assembly.
1- Turn off power to unit and shut off gas supply.
2- Remove screws holding the burner support cap.
3- Slide each burner off its orifice.
4- Clean and reassemble (reverse steps 1-3).
5- Be sure to secure all wires and check plumbing.
6- Turn on power to unit. Follow lighting instructions at-
tached to unit and operate unit in heating mode.
Check burner flames. They should be blue with yellow
streaks.
BURNER REMOVAL / SENSOR ORIENTATION
BURNERS
BURNER
SUPPORT
ORIFICE
FIGURE 29
8-Heat Exchanger
To Access or Remove Heat Exchanger From Unit:
1- Turn off gas and electric power.
2- Remove access panel(s) and unit center mullions.
3- Disconnect combustion air blower. Draw wires
through divider panel to allow for clearance of vest
panel. Remove access panel(s) and unit center mul-
lions.
4- Remove screws supporting heat exchanger.
5- To install heat exchanger, reverse procedure. Be sure
to secure all wires and check plumbing and burner
plate for airtight seal. Screws must be torqued to 35
in.-lbs. (4N.m) to ensure proper operation. Recaulk
corners of vest panel
BURNER
SUPPORT
CAP
SENSOR
9-Spark Electrode Gap
The spark electrode assembly can be removed for inspection
by removing two screws securing the electrode assembly
and sliding it out of unit.
For proper unit operation, electrodes must be positioned and
gapped correctly.
Spark gap may be checked with appropriately sized twist drills
or feeler gauges. Disconnect power to the unit and remove
electrode assembly. The gap should be between 0.125" +
0.015" (3.2 mm + .4 mm). See figure 22.
10-Flame Sensing
Flame current is an electrical current which passes from the
ignition control through the sensor electrode during unit op-
eration. The current passes from the sensor through the
flame to the ground electrode (located on the flame elec-
trode) to complete a safety circuit. The electrodes should be
located so the tips are at least 1/2" (12.7 mm) inside the
flame envelope. Do not bend electrodes. To measure flame
current, follow the procedure below:
Electrodes are not field adjustable. Any alter-
ations to the electrode may cause a hazardous
condition that can cause property damage or per-
sonal injury.
1- Disconnect power to unit.
2- Remove lead from sensing electrode and install a
0-50 DC microamp meter in series between the sens-
ing electrode and the sensing lead.
3- Reconnect power and adjust thermostat for
heating demand.
4- When flame is established, compare to table 24. Do
not bend electrodes.
5- Disconnect power to unit before disconnecting meter.
Make sure sensor wire is securely reconnected
before reconnecting power to unit.
NOTE-If the meter scale reads 0, the leads are re-
versed. Disconnect power and reconnect leads for
proper polarity.
Manufacturer
RAM
JOHNSON
FENWALL
Page 39
DANGER
TABLE 24
Nominal Signal
Drop Out
Microamps
1.7-3.6 0.5
0.5-1.0 .09
1.7-3.6 0.7