6
COMPONENT INFORMATION
COMBUSTION AIR REQUIREMENTS
The furnace components shown on pages 9 - 11 will help
to identify and locate various parts of the furnace. The
component you need to familiarize yourself with is the
gas valve. You will use this to turn the furnace on and off.
There are no user serviceable parts. All repairs must be
done by a licensed HVAC technician.
VENTING SYSTEM
This furnace is designed to fulfi ll the requirements of being
classifi ed as either a Category I or Category IV furnace.
These classifi cations are related to the furnace’s Annual
Fuel Utilization Effi ciency (AFUE) rating, the percentage
of fuel that is converted into usable heating energy.
Category I Furnaces
These furnaces typically have an AFUE rating of about
80% and may be vented through a properly designed metal
vent or masonry chimney. This venting system needs to
be primarily vertical, so that the hot combustion products
will develop a natural upwards draft action.
Category IV Furnaces
Category IV furnaces typically have an AFUE rating over
90% and are mainly vented through plastic PVC pipe.
These furnaces also produce liquid condensate which is
slightly acidic. The vent piping must be sloped upwards
away from the furnace to properly drain the condensate
back to the condensate disposal system.
THERMOSTATS
This family of furnaces includes single stage, two-stage and
modulating capabilities. These different capabilities require
different thermostats to reach their best performance.
Single stage furnaces (SA, SK, SC & SL models) should
be controlled by a conventional single stage thermostat.
Two stage furnaces (TA, TK, TC & TL models) will perform
best with a conventional two - stage thermostat. However,
it is possible to also control two stage furnaces with a
single stage thermostat. Both thermostats are commonly
available at your local building supply store. Consult
with your installer about which type is best for your
installation. The modulating MQ furnaces will not work
with a conventional thermostat and must be controlled by
an iQ thermostat, available through your dealer.
CAUTION:
Do not reduce the supply of fresh air to the
furnace. It is extremely important that the
furnace receives an unobstructed fl ow of clean,
fresh air to properly burn the fuel gas. If this
fl ow of air is restricted, the partially burned
combustion gases may create dangerous
amounts of carbon monoxide - a colorless,
odorless gas that is a deadly poison that can
cause personal injury or death.
Air openings on top of the furnace and openings in closet
doors or walls must never be restricted. If the furnace is
operated without adequate air for combustion, the fl ame
roll-out switch will open, turning off the gas supply to the
burners. This indicates that a serious problem with the
burners has occurred and must be corrected immediately.
Only a licensed HVAC technician can reset this switch.
Before remodeling near the furnace, consult with a local
code offi cial or the National Fuel Gas Code to make sure
you will be in compliance with supplying adequate air for
combustion. By erecting new walls, it is sometimes possible
to inadvertently restrict the furnace’s air supply. You can
fi nd more information about supplying combustion air in
the NFGC, which is available at many libraries.
SOURCES OF CORROSION
It is known that certain common household chemicals can
cause heat exchanger corrosion if the vapors are pulled into
the furnace’s burners The following is a list of chemicals
that should not be used or stored near the furnace.
Do not store these chemicals near the furnace:
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine based swimming pool chemicals
• Water softening chemicals
• De-icing salts or chemicals
• Carbon tetrachloride
• Halogen type refrigerants
• Cleaning solvents (perchloroethylene)
• Printing inks, paint removers, varnishes, etc.
• Hydrochloric acid
• Cements and glues
• Antistatic fabric softeners
• Masonry acid washing materials
FURNACE IN A SMALL ROOM OR CLOSET
If a furnace is installed in relatively small utility room or
closet, the installation needs openings in the walls or door
to let combustion air in. Make sure that these openings
remain unobstructed. Do not modify these openings in any
way without consulting a licensed HVAC technician.
Summary of Contents for *MQ 97%+ Upfl ow/Horizontal
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