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•     Blower and vestibule access panels must be in place 
on the furnace at all times.
•   The furnace heat exchanger, components, duct system, 
and evaporator coils must be thoroughly cleaned follow-
ing nal construction clean−up.
•    Air lters must be replaced upon construction comple-
tion. 
•    All furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be veried 
in accordance with these installation instructions.
EQUIPMENT MAY EXPERIENCE PREMATURE COM-
PONENT FAILURE AS A RESULT OF FAILURE TO FOL-
LOW THE ABOVE INSTALLATION INSTRUCTIONS. 
FAILURE TO FOLLOW THE ABOVE INSTALLATION IN-
STRUCTIONS VOIDS THE MANUFACTURER’S EQUIP-
MENT LIMITED WARRANTY. LENNOX DISCLAIMS 
ALL LIABILITY IN CONNECTION WITH INSTALLER’S 
FAILURE TO FOLLOW THE ABOVE INSTALLATION IN-
STRUCTIONS.
NOTWITHSTANDING THE FOREGOING, INSTALLER 
IS RESPONSIBLE FOR CONFIRMING THAT THE USE 
OF CONSTRUCTION HEAT IS CONSISTENT WITH THE 
POLICIES AND CODES OF ALL REGULATING ENTI-
TIES. ALL SUCH POLICIES AND CODES MUST BE AD-
HERED TO.
General
These instructions are intended as a general guide and do 
not supersede local codes in any way. Consult authorities 
having jurisdiction before installation.
In addition to the requirements outlined previously, the 
following general recommendations must be considered 
when installing a ML296UHV furnace:
•   Place the furnace as close to the center of the air distri-
bution system as possible. The furnace should also be 
located close to the vent termination point.
•   When the furnace is installed in non-direct vent applica-
tions, do not install the furnace where drafts might blow 
directly into it. This could cause improper combustion 
and unsafe operation.
•   When the furnace is installed in non-direct vent applica-
tions, do not block the furnace combustion air opening 
with clothing, boxes, doors, etc. Air is needed for proper 
combustion and safe unit operation.
•   When the furnace is installed in an attic or other insulat-
ed space, keep insulation away from the furnace.
•   When the furnace is installed in an unconditioned 
space, consider provisions required to prevent freezing 
of condensate drain system.
•   Please consult the manufacturer of your evaporator 
coil for their recommendations on distance required 
between the heat exchanger and their drain pan. Ad-
equate space must be provided between the drain pan 
and the furnace heat exchanger.
 CAUTION
ML296UHV unit should not be installed in areas normally 
subject to freezing temperatures.
 WARNING
Insucient  combustion  air  can  cause  headaches, 
nausea,  dizziness  or  asphyxiation.  It  will  also  cause 
excess water in the heat exchanger resulting in rusting 
and premature heat exchanger failure. Excessive 
exposure to contaminated combustion air will result 
in safety and performance related problems. Avoid 
exposure to the following substances in the combustion 
air supply:
Permanent wave solutions
Chlorinated waxes and cleaners
Chlorine base swimming pool chemicals
Water softening chemicals
De-icing salts or chemicals
Carbon tetrachloride
Halogen type refrigerants
Cleaning solvents (such as perchloroethylene)
Printing inks, paint removers, varnishes, etc.
Hydrochloric acid
Cements and glues
Antistatic fabric softeners for clothes dryers
Masonry acid washing materials
Combustion, Dilution & Ventilation Air
If the ML296UHV is installed as a Non-Direct Vent Fur-
nace, follow the guidelines in this section.
NOTE - In Non-Direct Vent installations, combustion air is 
taken from indoors or ventilated attic or crawlspace and 
ue gases are discharged out-doors.
In the past, there was no problem in bringing in sucient 
outdoor air for combustion. Inltration provided all the air 
that was needed. In today’s homes, tight construction 
practices make it necessary to bring in air from outside for 
combustion. Take into account that exhaust fans, appli-
ance vents, chimneys, and replaces force additional air 
that could be used for combustion out of the house. Un-
less outside air is brought into the house for combustion, 
negative pressure (outside pressure is greater than inside 
pressure) will build to the point that a downdraft can oc-
cur in the furnace vent pipe or chimney. As a result, com-
bustion gases enter the living space creating a potentially 
dangerous situation.
In the absence of local codes concerning air for combus-
tion and ventilation, use the guidelines and procedures in 
this section to install ML296UHV furnaces to ensure e-
cient and safe operation. You must consider combustion 
air needs and requirements for exhaust vents and gas 
piping.