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Multistory and common venting are prohibited.
DIRECT VENT/2-PIPE SYSTEM (ALL SIZES)
In a direct-vent (2-pipe) system, all air for combustion is taken
directly from outdoor atmosphere, and all flue products are
discharged to outdoor atmosphere. A factory accessory vent
termination kit MUST be used in a direct vent (2-pipe) system.
NON-DIRECT VENT/1-PIPE SYSTEM (SIZES 040 THROUGH
120 ONLY)
In a non-direct vent (1-pipe) system, all air for combustion is taken
from the area adjacent to furnace, and all flue products are
discharged to outdoor atmosphere. A factory-supplied perforated
disk assembly (in loose parts bag) MUST be used in combustion-
air pipe elbow.
CARBON MONOXIDE POISONING HAZARD
Failure to follow the steps outlined below for each appliance
connected to the venting system being placed into operation
could result in carbon monoxide poisoning or death.
The following steps shall be followed for each appliance
connected to the venting system being placed into operation,
while all other appliances connected to the venting system are
not in operation:
1. Seal any unused openings in venting system.
2. Inspect the venting system for proper size and horizontal
pitch, as required in the National Fuel Gas Code, ANSI
Z223.1-2002/NFPA 54-2002 or the CSA B149.1, Natu-
ral Gas and Propane Installation Code and these instruc-
tions. Determine that there is no blockage or restriction,
leakage, corrosion and other deficiencies, which could
cause an unsafe condition.
3. As far as practical, close all building doors and windows
and all doors between the space in which the appli-
ance(s) connected to the venting system are located and
other spaces of the building.
4. Close fireplace dampers.
5. Turn on clothes dryers and any appliance not connected
to the venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they are operat-
ing at maximum speed. Do not operate a summer
exhaust fan.
6. Follow the lighting instructions. Place the appliance
being inspected into operation. Adjust the thermostat so
appliance is operating continuously.
7. Test for spillage from draft hood equipped appliances at
the draft hood relief opening after 5 minutes of main
burner operation. Use the flame of a match or candle.
8. If improper venting is observed during any of the above
tests, the venting system must be corrected in accordance
with the National Fuel Gas Code, ANSI Z223.1-
2002/NFPA 54-2002 and/or CSA B149.1, Natural Gas
and Propane Installation Codes.
9. After it has been determined that each appliance con-
nected to the venting system properly vents when tested
as outlined above, return doors, windows, exhaust fans,
fireplace dampers and any other gas-fired burning appli-
ance to their previous conditions of use.
MATERIALS
Combustion-air and vent pipe, fittings, primers, and solvents must
conform to American National Standards Institute (ANSI) stan-
dards and American Society for Testing and Materials (ASTM)
standards. See Table 7 for approved materials for use in the U.S.A.
FIRE AND EXPLOSION HAZARD
Failure to follow this warning could result in fire, property
damage, personal injury, or death.
Solvent cements are combustible. Keep away from heat,
sparks, and open flame. Use only in well-ventilated areas.
Avoid breathing in vapor or allowing contact with skin or
eyes.
In Canada, construct all combustion-air and vent pipes for this unit
of CSA or ULC listed schedule-40 PVC, PVC-DWV or ABS-
DWV pipe and pipe cement. SDR pipe is NOT approved in
Canada.
In direct vent (2-pipe) systems, combustion air and vent pipes must
terminate together in same atmospheric pressure zone, either
through roof or sidewall (roof termination preferred), using acces-
sory termination kit. See Table 8 for required clearances.
In non-direct vent (1-pipe) system, vent pipe termination must be
installed with adequate clearances to building openings and
equipment to comply with national and local codes. See Table 9
for required clearances.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in property
damage, personal injury, or death.
All combustion-air and vent pipes must be airtight and
watertight. Pipes must also terminate exactly as shown in Fig.
42 for direct vent (2-pipe) system and Fig. 43 for non-direct
vent (1-pipe) system.
An abandoned masonry chimney may be used as a raceway for
properly insulated and supported combustion-air (when appli-
cable) and vent pipes. Each furnace must have its own set of
combustion-air and vent pipes and be terminated individually, as
shown in Fig. 42 for Direct Vent (2-Pipe) system and Fig. 43 for
Non-Direct Vent (1-Pipe) system.
A furnace shall not be connected to a chimney flue serving a
separate appliance designed to burn solid fuel.
Other gas appliances with their own venting system may also use
the abandoned chimney as a raceway providing it is permitted by
local code, the current edition of the National Fuel Gas Code and
the vent or liner manufacturer’s installation instructions. Care must
be taken to prevent the exhaust gases from one appliance from
contaminating the combustion air of other gas appliances.
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent unit
operation.
When vent pipe is exposed to temperatures below freezing,
such as when it passes through an unheated space or when a
chimney is used as a raceway, pipe must be insulated as
shown in Table 10 with Armaflex-type insulation.
Furnace combustion air and vent pipe connections are sized for
2-in. pipe. Any pipe size change should be made outside furnace
casing in vertical pipe. The transition has to be made as close to the
furnace as reasonably possible.
COMBUSTION AIR PIPE
General
Furnace combustion-air connection must be attached as shown in
Fig. 37. Combustion-air intake housing plug may need to be
relocated in some applications.
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