e. Gas valve
f. Hot surface ignitor
g. Flame-sensing electrode
6. Remove 8 screws that secure flue collector box to center panel. Be careful not to damage sealant.
7. Remove complete inducer assembly from furnace, exposing flue openings.
8. Clean cells using field-provided small wire brush, steel spring cable, reversible electric drill, and vacuum cleaner.
a. Assemble wire brush and steel spring cable.
(1.) Use 48 in. of 1/4-in. diameter high-grade steel spring cable (commonly known as drain clean-out or Roto-Rooter cable).
(2.) Use 1/4-in. diameter wire brush (commonly known as 25-caliber rifle cleaning brush).
NOTE:
The materials needed in items (1.) and (2.) can usually be purchased at local hardware stores.
(3.) Insert twisted wire end of brush into end of steel spring cable, and crimp tight with crimping tool or strike with ball-peen hammer.
TIGHTNESS is very important.
(4.) Remove metal screw fitting from wire brush to allow insertion into cable.
b. Clean each heat exchanger cell.
(1.) Attach variable-speed, reversible drill to end of steel spring cable (end opposite brush).
(2.) Insert brush end of cable into upper opening of cell and slowly rotate with drill. DO NOT force cable. Gradually insert at least 36
in. of cable into 2 upper passes of cell. (See Fig. 8.)
(3.) Work cable in and out of cell 3 or 4 times to obtain sufficient cleaning. DO NOT pull cable with great force. Reverse drill and
gradually work cable out.
(4.) Remove burner assembly and cell inlet plates.
CAUTION: Be very careful when removing the burner assembly to avoid breaking the ignitor. See Fig. 9 for the correct
ignitor location.
(5.) Replace screws in center panel and cells before cleaning.
(6.) Insert brush end of cable in lower opening of cell, and proceed to clean 2 lower passes of cell in same manner as 2 upper passes.
(7.) Repeat foregoing procedures until each cell in furnace has been cleaned.
(8.) Remove residue from each cell using vacuum cleaner.
Fig. 8—Cleaning Heat Exchanger Cell
A91252
Fig. 9—Position of Ignitor to Burner
A93347
BURNER
IGNITOR
11 32
"
7 8
"
C
L
C
L
IGNITOR
ASSEMBLY
CELL
PANEL
BURNER
13 32
"
HOT
SURFACE
IGNITOR
ASSEMBLY
—6—