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which might affect combustion can then do so without
causing the unit to start sooting/smoking. Things which
might affect combustion include a nozzle going bad,
draft that changes during different climatic conditions,
dirty oil, dirt obstructing the air inlet, etc.
To build in a window of operation," set up the burner to
be 2% less in CO
2
. For example, if you find a reading of
12% CO
2
, adjust the air shutter (and air band, if neces-
sary) to increase the air and drop the CO
2
to 10%.
5.
Retest the Smoke
With a drop in the CO
2
and in-
crease in the air you should see that the smoke has re-
turned to 0.
6.
Retest the Overfire Draft
This test serves to confirm
that you have not increased the air too much. Again
you do not want a positive pressure at the test port. It
should still be 0.02 less than the draft pressure reading
taken at the breach. You may need to increase the
stack draft by adjusting the barometric draft control.
7.
Stack Temperature
Take a stack temperature read-
ing in the vent pipe. Subtract the room air temperature
from the stack temperature. This will give you the net
stack temperature. Use the efficiency charts provided
in most CO
2
analyzers to determine furnace efficiency.
8. When the proper combustion and smoke readings
have been achieved, re−tighten the air shutter screw(s)
and air band screw.
Service
CAUTION
Do not tamper with unit controls. Call your qualified
service technician.
A − Servicing Filter
NOTE − Under no circumstances should the access panels
to the blower compartment be left off or left partially open.
Throw-Away Type Filters
Check filters monthly and re-
place when necessary to assure proper furnace operation.
Replace filters with like kind and size filters.
Reusable Type Filters Filters should be checked month-
ly and cleaned when necessary to assure proper furnace
operation. Use warm water and a mild detergent. Replace
filter when dry. Permanent filters supplied with ELO183UF
furnaces do not require oiling after cleaning. Examine filter
label for any for special instructions that may apply.
B − Blower
Blower motor is prelubricated and sealed for extended op-
eration. No further lubrication is required. Disconnect pow-
er to unit before cleaning blower wheel for debris.
C − Flue Pipe Inspection
The flue pipe should be inspected annually by a qualified
service technician. Remove and clean any soot or ash
found in the flue pipe. Inspect pipe for holes or rusted
areas. If replacement is necessary, replace with the same
size and type as required by code. Inspect the flue baro-
metric draft control and replace if found to have failed.
D − Cleaning the Heat Exchanger
1 − Remove the vent pipe from the furnace.
2 − Remove the locking screws and the caps from the
clean out tubes. Remove flue access elbow.
3 − Using a long spiral wire brush, sweep down the outer
drum of the heat exchanger. Then using the hose at-
tachment, vacuum out loose debris.
4 − Remove the locking screw and cap from the observa-
tion tube and with the spiral wire brush, reach upward
toward the rear of the heat exchanger to clean out the
crossover tube.
CAUTION
Do not attempt to clean the combustion chamber. It
can be easily damaged.
5 − Replace the clean out caps and flue access elbow.
Make sure locking screws are secure.
6 − Brush out and vacuum the vent outlet area of the outer
drum and replace vent pipe.
7 − Clean around the burner, blower deck and vestibule
area.
NOTE − A heat exchanger clean-out kit ABRSH380
(35K09) is available from Lennox. The kit includes a ra-
diator brush, a tapered brush and a non−metallic 36"
spiral wire handle.
