Lennox International Inc. G20 - Manual (Page 5)

3DJH 
Filters
G20E and G20X series units are equipped with reusable
filters which should be inspected monthly and cleaned
when necessary to assure proper furnace operation. See
table 1 for filter sizes. Use the following procedure to
clean filter.
1- Turn off electric power to furnace.
2- Remove blower access panel. Wait for blower to stop.
3- Remove filter by sliding up and out of filter brackets.
4- Wash filter with water and a mild detergent. For in-
creased efficiency, filter media should be sprayed
with filter Handicoater when dry. Filter Handicoater is
RP products no. 418 and is available as Lennox part
no. P-8-5069.
NOTE-If filter media must be replaced, order Lennox
part no. P-9-7831 for 20” x 25 ” filter, P-8-7822 for 16”
x 25” filter, 97H0601 for 18” x 25” filter, 97H0701 for
25” x25” filter, and 97H0801 for 24” x 30” filter.
5- Reinstall filter. Slide filter into top bracket and drop
into lower bracket.
NOTE-Do not replace reusable foam filters with
throw-away filters.
6- Replace blower access panel.
02'(/ 12
),/7(5 6,=(
Q2-50, Q3-50, Q2-75,
Q3-75,
Q5/6-100, Q3/4-125,
Q5/6-125
16 X 25 X 1
20 X 25 X 1
6,'( 5(7851 %27720 5(7851
16 X 25 X 1
4  20 X 25 X 1  ;  ; 
 ;  ; 
7$%/( 
Q4-75, Q3/4-100 16 X 25 X 1 18 X 25 X 1
Blower
Check and clean blower wheel for any debris. Blower mo-
tor is prelubricated for extended bearing life. No further lu-
brication is needed.
Pilot and Burner Flame
CAUTION
Check pilot flame and burner flame periodically to
ensure proper operation.
1- Pilot Flame -- Pilot flame must surround the end of
flame sensor for proper operation of pilot safety cir-
cuit. See figure 7.
PILOT FLAME
(Side View)
BURNER
PILOT GAS
LINE
ELECTRODE
(G20E & G20X)
FIGURE 7
FLAME SENSOR
2- Burner Flame -- Start burner and allow to operate for
a few minutes to establish normal burning condi-
tions. Check burner flame by observation. Flame
should be predominantly blue in color, strong in ap-
pearance and should rise directly from the burner
ports in the heat exchanger. Check to see that flame
is burning from all continuous ribbon ports and that
flame does not impinge on the sides of the heat ex-
changer. See figure 8.
BURNER FLAME
FIGURE 8
NOTE-VIEW BURNER FLAME
THROUGH OBSERVATION PORT ON
BURNER BOX OR DAMPER OPENING
(Not Shown)
VENTING SYSTEM INSPECTION
Annually (before heating season) inspect furnace venting
system, draft hood, vent cap, heat exchanger, burners
and pilot for corrosion, deterioration, or deposits of de-
bris. Remove any obstructions.
Contact your Lennox dealer for a periodic unit inspection
by a qualified service technician.
BLOCKED VENT SHUT-OFF SYSTEM
Your Lennox furnace is equipped with a blocked vent
shut-off switch and a flame roll-out switch. The blocked
vent shut-off switch shuts off the gas supply to the furnace
in the event of flue or vent blockage. The flame roll-out
switch shuts off the gas supply to the furnace if there is a