Carrier 120/C Series Installation, Start-Up, Operating And Service And Maintenance Instructions page 47

9/32˝
Fig. 57—Igniter Position-Side View
quality combustion air, incorrect size or damaged manifold ori-
fice(s), improper gas, or a restricted heat exchanger. Action must
be taken to correct the problem.
If it becomes necessary to clean the heat exchangers because of
dust or corrosion, proceed as follows:
1. Turn OFF gas and electrical power to furnace.
2. Remove outer access door.
3. Disconnect vent connector from furnace vent elbow.
4. For downflow or horizontal furnace having an internal vent
pipe, remove internal vent pipe within the casing.
5. Disconnect wires to the following components. Mark wires to
aid in reconnection of (be careful when disconnecting wires
from switches because damage may occur):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switch(es).
d. Limit overtemperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switches.
6. Remove screws that fasten the collector box assembly to the
cell panel. Be careful not to damage the collector box. Inducer
assembly and elbow need not be removed from collector box.
7. Disconnect gas line from gas manifold.
8. Remove the 5 screws that attach the burner assembly to the
cell panel. The gas valve and individual burners need not be
removed from support assembly. Remove NOx baffles if
installed.
NOTE: Be very careful when removing burner assembly to avoid
breaking igniter. See Fig. 57 and 58 for correct igniter location.
9. Using field-provided 25-caliber rifle cleaning brush, 36-in.
long, 1/4" diameter steel spring cable, a variable speed,
reversible electric drill, and vacuum cleaner, clean cells as
follows:
a. Remove metal screw fitting from wire brush to allow
insertion into cable.
b. Insert the twisted wire end of brush into end of spring
cable, and crimp tight with crimping tool or crimp by
striking with ball-peen hammer. TIGHTNESS IS VERY
IMPORTANT.
NOTE: The materials needed in item 9 can usually be purchased
at local hardware stores.
5/16˝
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10. Remove old sealant from cell panel and collector box flange.
11. Spray releasing agent on the heat exchanger cell panel where
NOTE: A releasing agent such as cooking spray or equivalent
(must not contain corn or canola oil, aromatic or halogenated
hydrocarbons or inadequate seal may occur) and RTV sealant
(G.E. 162, 6702, or Dow-Corning 738) are needed before starting
installation. DO NOT substitute any other type of RTV sealant.
G.E. 162 (P771-9003) is available through RCD in 3-oz tubes.
12. Apply new sealant to flange of collector box and attach to cell
13. Reconnect wires to the following components. (Use connec-
14. Reinstall internal vent pipe, if applicable.
47
Fig. 58—Igniter Position-Top View
(1.) Attach variable-speed, reversible drill to the end of
spring cable (end opposite brush).
(2.) Insert brush end of cable into the outlet opening of cell
and slowly rotate with drill. DO NOT force cable.
Gradually insert cable into upper pass of cell. (See Fig.
59.)
(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.) Insert brush end of cable in burner inlet opening of
cell, and proceed to clean 2 lower passes of cell in
same manner as upper pass.
(5.) Repeat foregoing procedures until each cell in furnace
has been cleaned.
(6.) Using vacuum cleaner, remove residue from each cell.
(7.) Using vacuum cleaner with soft brush attachment,
clean burner assembly.
(8.) Clean flame sensor with fine steel wool.
(9.) Install NOx baffles (if removed).
(10.) Reinstall burner assembly. Center burners in cell
openings.
collector box assembly contacts cell panel.
panel using existing screws, making sure all screws are secure.
tion diagram on wiring label, if wires were not marked for
reconnection locations.):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switch(es).
d. Limit over-temperature switch.
e. Gas valve.
f. Hot surface igniter.
g. Flame-sensing electrode.
h. Flame rollout switches.
i. Install NOx baffles (if removed).
1-7/8"
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