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Safety Precautions

If you discover any of the following, shut down your 

unit, and contact a Lennox dealer for an inspection by 

a licensed professional service technician (or equiv-

alent).

• 

 If you repeatedly hear any new or unfamiliar sounds 

while your unit is operating, there may be a prob

-

lem.  For  example,  poorly  performing  burners  can 

produce unfamiliar noises. 

• 

 If you smell any unusual odors, your unit may be 

operating improperly. For example, units can give 

off unfamiliar odors if components are required to 

operate in abnormal conditions.

• 

   Look for visible signs of a malfunctioning unit. Ex

-

amples include unusual amounts of condensate on 

windows  inside  your  house,  visibly  burnt  compo

-

nents or unusual dirt or rust accumulations on the 

vent pipe or in the unit.

•     If you experience headache, nausea, fatigue, or 

dizziness, the cause could be exposure to carbon 

monoxide gas. This is often misdiagnosed as the 

flu because symptoms are similar. If you suffer from 

flu-like  symptoms  that  are  exaggerated  at  home, 

but seem to subside while you are away from the 

house, exposure to carbon monoxide could be the 

cause.

Your vigilance may pay off in early detection of a problem 

before either personal injury or property damage occurs. 

Do not hesitate to contact a qualified service technician as 

an investment in your well being.

 WARNING

Do not use this furnace if any part has been 

underwater. A flood-damaged furnace is extremely 

dangerous. Attempts to use the furnace can result 

in  fire  or  explosion.  Immediately  call  a  licensed 

professional service technician (or equivalent) to 

inspect the furnace and to replace all gas controls, 

control system parts, and electrical parts that 

have been wet or to replace the furnace, if deemed 

necessary.

Planned Service

Annual Furnace Maintenance

At the beginning of each heating season, and to comply 

with the 

Lennox Limited Warranty,

 your system should 

be checked as follows by a licensed professional service 

technician (or equivalent).

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.

4 - 

 Check  the  cleanliness  of  filters  and  change  if 

necessary (monthly).

5 - 

 Check the condition and cleanliness of burners and 

heat exchanger and clean if necessary.

6 - 

 Check  the  cleanliness  of  blower  assembly  and 

clean the housing, blower wheel and blower motor 

if necessary

7 - 

.  Inspect  the  combustion  air  inducer  and  clean  if 

necessary.

8 - 

 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

9 - 

 Ensure sufficient 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.

10 - 

 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

11 -  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.

12 - 

 Check the condition of the furnace cabinet insulation 

and repair if necessary.

13 - 

 Perform a complete combustion analysis during the 

furnace  inspection  to  ensure  proper  combustion 

and operation. Consult Service Literature for proper 

combustion values.

14 - 

 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-

off operation.

1 - 

Check the operation of the ignition system, inspect 

and clean flame sensor. Check microamps before and 

after. Check controls and safety devices (gas valve, 

flame  sensor,  temperature  limits).  Consult  Service 

Manual  for  proper  operating  range.  Thermal  Limits 

should  be  checked  by  restricting  airflow  and  not 

disconnecting the indoor blower. For additional details, 

please see Service and Application Note H049.

2 - 

 Verify that system total static pressure and airflow 

settings are within specific operating parameters.

Summary of Contents for ML180UHE

Page 1: ...ings exactly could result in serious injury death or property damage Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any other appliance Installation and...

Page 2: ...on will stop If your home is left unattended for an extended period of time equipment operation must be checked periodically If this is not possi ble the water supply to the house should be shut off a...

Page 3: ...as pressure and gas flow rate adequate combustion air and proper venting WARNING Asphyxiation Hazard The exhaust vent for this furnace must be leak free and must be securely connected to the furnace f...

Page 4: ...try to light the burners by hand 5 Remove the access panel 6 Move switch on gas valve to OFF Do not force See figure 2 7 Wait five minutes to clear out any gas If you then smell gas STOP Immediately c...

Page 5: ...n inspect furnace venting system vent cap heat exchanger and burners for corro sion deterioration or deposits of debris Remove any ob structions Inspect the furnace venting system to make sure it is i...

Page 6: ...or 2 Check the condition of the belt and shaft bearings if applicable 3 Inspect all gas pipe and connections for leaks 4 Check the cleanliness of filters and change if necessary monthly 5 Check the co...

Page 7: ...innocently stored next to the furnace may obstruct the combustion air supply This could cause incomplete combustion and the produc tion of carbon monoxide gas Repair Parts List The following repair pa...

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