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All field wiring must comply with local codes or what is
listed in these instructions.
When furnace is installed so that supply ducts carry air cir
culated by furnace to areas outside of space containing
ufurnace, return air shall be handled by a duct(s) sealed to
a furnace casing and terminating outside space containing
furnace.
NOTE - ML180UHT series units must not be used as a
“construction heater” during any phase of construction.
Very low temperatures, harmful vapors and misplacement
of the filters will damage the unit and its efficiency.
The ML180UHT furnace may be installed in alcoves, clos
ets, attics, basements, garages, crawl spaces and utility
rooms in any of its approved installation positions.
This furnace design has not been approved for instal
lation in mobile homes, recreational vehicles, or out
doors.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju
ry or death.
General
These instructions are intended as a general guide and
do not supersede local codes in any way. Consult au
thorities having jurisdiction before installation.
In addition to the requirements outlined previously, the fol
lowing general recommendations must be considered
when installing a ML180UHT furnace:
Place the furnace as close to the center of the air dis
tribution system as possible. The furnace should also be
located close to the chimney or vent termination point.
Do not install the furnace where drafts might blow direct
ly into it. This could cause improper combustion and un
safe operation.
Do not block the furnace combustion air openings 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 insu
lated space, keep insulation away from the furnace.
WARNING
The State of California has determined that this prod
uct may contain or produce a chemical or chemicals,
in very low doses, which may cause serious illness
or death. It may also cause cancer, birth defects or
reproductive harm.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient
outdoor air for combustion. Infiltration provided all the air
that was needed. In today's homes, tight construction prac
tices make it necessary to bring in air from outside for com
bustion. Take into account that exhaust fans, appliance
vents, chimneys, and fireplaces force additional air that
could be used for combustion out of the house. Unless out
side 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 occur in the fur
nace vent pipe or chimney. As a result, combustion gases
enter the living space creating a potentially dangerous situ
ation.
CAUTION
Do not install the furnace in a corrosive or contami
nated atmosphere. Meet all combustion and ventila
tion air requirements, as well as all local codes.
