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Annual Furnace Maintenance
At the beginning of each heating season, and to comply 
with the Lennox Limited Warranty, your system should 
be  checked  by  a  licensed  professional  technician  (or 
equivalent) as follows:
A “Disconnected Vent” warning sticker should be attached 
to a visible area of the plenum near the vent pipe. If the 
sticker  is  not  legible  or  missing,  order  kit  66W04  for  re-
placement stickers.
1 -   Check  wiring  for  loose  connections,  voltage  at 
indoor unit and amperage of indoor motor.
2 -   Check the condition of the belt and shaft bearings 
if applicable.
3 -   Inspect all gas pipe and connections for leaks.
 Check the  cleanliness of lters and change  if necessary 
(monthly).
 IMPORTANT
If  a  higheciency  lter  is  being  installed  as  part 
of this system to ensure better indoor air quality, 
the  lter  must  be  properly  sized.  Higheciency 
lters  have  a  higher  static  pressure  drop  than 
standardeciency glass/foam lters. If the pressure 
drop is too great, system capacity and performance 
may be reduced.
The pressure drop may also cause the limit to trip 
more frequently during the winter and the indoor 
coil to freeze in the summer, resulting in an increase 
in the number of service calls.
Before using  any lter with this  system,  check the 
specications  provided  by  the  lter  manufacturer 
against the data given in the appropriate Lennox 
Product  Specications  bulletin.  Additional 
information is provided in Service and Application 
Note ACC002 (August 2000).
4 -   Check the condition and cleanliness of burners and 
heat exchanger and clean if necessary.
5 -   Check  the  cleanliness  of  blower  assembly  and 
clean the housing, blower wheel and blower motor 
if necessary . The blower motors are prelubricated 
for  extended  bearing  life.  No  further  lubrication  is 
needed.
6 -   Inspect  the  combustion  air  inducer  and  clean  if 
necessary.
7 -   Evaluate the heat exchanger integrity by inspecting 
the  heat  exchanger  per  the AHRI  heat  exchanger 
inspection  procedure.  This  procedure  can  be 
viewed at www.ahrinet.org.
8 -   Ensure sucient combustion air is available to the 
furnace.  Fresh  air  grilles  and  louvers  (on  the  unit 
and  in  the  room  where  the  furnace  is  installed) 
must be properly sized, open and unobstructed to 
provide combustion air.
9 -   Inspect  the  furnace  venting  system  to  make  sure 
it is in place, structurally sound, and without holes, 
corrosion,  or  blockage.  Vent  system  must  be  free 
and  clear  of  obstructions  and  must  slope  upward 
away  from  the  furnace  .  Vent  system  should  be 
installed per the National Fuel Gas Code
10 -  Inspect  the  furnace  return  air  duct  connection  to 
ensure the duct is sealed to the furnace. Check for 
air leaks on supply and return ducts and seal where 
necessary.
11 -  Check the condition of the furnace cabinet insulation 
and repair if necessary.
12 -  Perform a complete combustion analysis during the 
furnace  inspection  to  ensure  proper  combustion 
and operation. Consult Service Literature for proper 
combustion values.
13 -  Verify  operation  of  CO  detectors  and  replace 
batteries as required.
Perform  a  general  system  test.  Turn  on  the  furnace  to 
check operating functions such as the start-up and shut-
o operation.
1 -   Check the operation of the ignition system, inspect 
and  clean  ame  sensor.  Check  microamps  before 
and  after.  Check  controls  and  safety  devices  (gas 
valve,  ame  sensor,  temperature  limits).  Consult 
Service Manual for proper operating range. Thermal 
Limits should be checked by restricting airow and 
not disconnecting the indoor blower. For additional 
details,  please  see  Service  and  Application  Note 
H049.
2 -   Verify that system total static pressure and airow 
settings are within specic operating parameters.
3 -   Clock gas meter to ensure that the unit is operating 
at  the  specied  ring  rate.  Check  the  supply 
pressure and the manifold pressure. On two-stage 
gas furnaces check the manifold pressure on high 
re and low re. If manifold pressure adjustment is 
necessary,  consult  the  Service  Literature  for  unit 
specic  information  on  adjusting  gas  pressure. 
Not  all  gas  valves  are  adjustable.  Verify  correct 
temperature rise.