Service - Lennox OHR23-105 Installation Instructions Manual

2. Perform Overfire Draft
Perform this test with the burner in operation. Remove
the screw from the center of the inspection port. Insert
the draft gauge into the hole.
A reading of the overfire draft should be 0.02 inches
w.c. less than the reading found in the vent connector
during the Draft Test. If a positive reading is seen at
this point, the combustion fan is pumping too much air
into the heat exchanger. Make the necessary adjust-
ments at the air adjustment dial.
3. Perform Smoke Test
Perform the smoke test at the same hole drilled in step 1.
Do not exceed #1 smoke.
4. Perform CO Test
2
Obtain the CO sample at the vent pipe. With the unit
2
firing at a trace of smoke, take a sample of the CO
From the results of this test, a window of operation"
(operational tolerance) will be determined. The built-in
tolerance provides room within the set-up for elements
affecting combustion. Those things which might affect
combustion can then do so without causing the unit to
start sooting/smoking. Things which might affect com-
bustion include a nozzle going bad, draft that changes
during different climatic conditions, dirty oil, dirt obstruct-
ing the air inlet, etc.
To build a window of operation, set the burner up so it
does not exceed 13% co2.
5. Retest the Smoke
With a drop in the CO
should see that the smoke has returned 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. Perform Stack Temperature Test
Take a stack temperature reading in the vent pipe.
Subtract the room air temperature from the stack tem-
perature. This will give you the net stack temperature.
Use the efficiency charts provided in most CO
ers to determine furnace efficiency.

Service

Servicing Filter
NOTE − Under no circumstances should the access panels to
the blower compartment be left off or left partially open.
1. Throw-Away Type Filters
monthly and replaced when necessary to assure prop-
and increase in the air you
2
analyz-
2
Filters should be checked
er furnace operation. Replace filters with like kind and
size filters.
2. Reusable Type Filters
monthly and cleaned when necessary to assure prop-
er furnace operation. Use warm water and a mild de-
tergent. Replace filter when dry. Permanent filters sup-
plied with OHR23 furnaces do not require oiling after
cleaning. Examine filter label for any for special in-
structions that may apply.
Servicing Blower
Blower motor is pre−lubricated and sealed for extended op-
eration. No further lubrication is required. Disconnect pow-
er to unit before cleaning blower wheel for debris.
Servicing Nozzle
Replace nozzle every year to to ensure proper operation.
.
2
Clogged nozzles will result in improper firing or non-firing of
unit.
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 draft
control device and replace if found defective.
Cleaning 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.
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 burner, blower deck and vestibule area.
NOTE − A heat exchanger clean-out kit ABRSH380
(35K09) is available from Lennox.
Page 16
Filters should be checked
CAUTION