Combustion And Ventilation Air; Venting - Lennox LS25 Series Installation Instructions Manual

Combustion and Ventilation Air

Adequate facilities for supplying air for combustion and
ventilation must be provided in accordance with the cur-
rent edition of ANSI Z223.1, section 5.3 and CSA-B149
installation compliance codes, or applicable provisions of
local building codes.
All gas-fired appliances require air to be used for com-
bustion. In many buildings today, there is a negative in-
door air pressure caused by exhaust fans, etc. If sufficient
quantities of combustion air are not available, the heater
or another appliance will operate in an inefficient manner,
resulting in incomplete combustion which can result in the
production of excessive carbon monoxide.
WARNING
Insufficient 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
This unit must be provided with a combustion air pipe that
is connected to the outside atmosphere. Outdoor air must
be free of the following substances or the life of the heat
exchanger will be adversely affected: chlorine, carbon tet-
rachloride, cleaning solvent, halogen refrigerants, acids,
cements and glues, printing inks, fluorides, paint remov-
ers, varnishes, or any other corrosives.

Venting

NOTE - The vent is a passageway, vertical or nearly so,
used to convey flue gases from an appliance, or its vent
connector, to the outside atmosphere. The vent connector
is the pipe or duct that connects a fuel-gas-burning appli-
ance to a vent or chimney.
NOTE - Local codes may supersede any of these provisions.
GENERAL RECOMMENDATIONS AND
Unit heaters must be vented in compliance with the lat-
est edition of the National Fuel Gas Code (NFPA 54 /
ANSI Z223.1) in the USA and with CSA-B149.1 codes in
Canada, as well as applicable provisions of local building
codes, and the following instructions.
Vent piping must be in compliance with UL 1738 for
installations in the United States, and ULC S636 for
installations in Canada. Refer to venting sections for
vent termination clearance requirements.
Note - Different manufacturers have different joint
systems and adhesives. Do not mix pipe, fittings or
joining methods from different manufacturers.
A sheet metal transition is supplied with this certified
unit. It must not be modified or altered and must be
installed on the outlet of the combustion air inducer
assembly prior to the installation of the vent connec-
tor. Failure to comply with this requirement will void
the certification of the unit by the approval agencies.
Concentric venting is not approved for use in either
vertical or horizontal vent applications.
A single-wall vent connector may be used between the
furnace and the vertical vent pipe in all applications; how-
ever, single-wall vent material cannot be used for
vertical vent piping in residential applications. UL-ap-
proved Category III venting materials must be used
in all residential applications which vent horizontally.
A single-wall vent pipe used as a vent connector in resi-
dential or commercial applications, or as a vertical vent in
commercial applications, must have all seams and joints
sealed with pressure-sensitive aluminum tape or silicone
rubber sealant. The aluminum tape must have a tem-
perature rating of at least 400°F (204°C), i.e., 3M 433 or
equivalent. Silicone rubber sealant must have a tempera-
ture rating of 482°F (250°C), i.e., Dow Corning RTV-736
or equivalent. All joints must be secured with at least two
corrosion-resistant screws. All joints must be checked for
gas tightness after installation. Single-wall vent pipe used
as vertical vent in commercial applications must not pass
through any attic, interior wall, concealed space, or floor.
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REQUIREMENTS