5
Furnace Components
The furnace components on page 8 will help you locate
the different parts of the furnace. The control 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 should be done by a licensed
HVAC technician.
Venting System
This furnace is designed to fulfi ll the requirements of being
classifi ed as a Category IV furnace. This classifi cation is
related to the furnace’s Annual Fuel Utilization Effi ciency
(AFUE) rating. AFUE is the percentage of fuel that is
converted into usable heating energy.
Category IV Furnaces
Category IV furnaces typically have an AFUE rating over
90%. These furnaces are typically vented through plastic
pipe.
DESCRIPTION OF FURNACE
COMBUSTION AIR REQUIREMENTS
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.
Here is a problem that should be avoided. Sometimes a
furnace is properly installed and located in an unfi nished
part of the home. Later, the homeowner decides to
remodel this area. By erecting new walls, it is sometimes
possible to inadvertently restrict the furnace’s air supply.
Before remodeling near the furnace, consult with a local
code offi cial to make sure you will be in compliance with
supplying adequate air for combustion or refer to the
National Fuel Gas Code. 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 they 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 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.
