___>
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
AIR
COMBUSTION-AIR _ COMBUSTION-AIR
UPFLOW
COMBUSTION-
AIR
VENT
HORIZONTAL-LEFT DISCHARGE
NOTE: Select 1 vent pipe connection and
1 combustion-air pipe connection.
COMBUSTION- _ COMBUSTION-
AIR AIR
AIR
FLOW
DOWNFLOW
COMBUSTION-
AIR
VENT
HORIZONTAL-RIGHT DISCHARGE
A96187
Fig. 33--Combustion°Air and Vent Pipe
Connections
NOTE: Slope combustion-aiI and _ent pipes a minimum of I4
in. per linear ft with no sags between hangers.
MINOR PROPERTY DAMAGE
Failure to %llow this caution may result in water damage
from condensate dripping.
When combustion-air pipe is installed above a suspended
ceiling, pipe must be insulated with 3ig=in. thick Armaflex=
type insulation Combustion=air pipe should also be insulated
when it passes through wam_, humid space
UNIT MAY NOT OPERATE
Failure to %llow this caution may result in intem_ittent 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 g with Armaflex=type insulation
An abandoned masonry chinmey may be used as a raceway %r
properly insulated and supported combustion=air and vent pipes.
Each fltrnace must have its own set of combustion-air and vent
pipes and be terminated individually, as shown in Fig. 41
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 cmTent edition of the National Fuel Gas (:ode and
the vent or liner manufi_cmrer'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 CORROSION HAZARD
Excessive exposure to contaminated combustion air may
result in safety and perfbrmance related problems.
(ombustion air must not be taken flom inside structure
because inside air is frequently contaminated by halogens,
which include fluorides, chlorides, bromides, and iodides.
These elements are fbund in aerosols, detergents, bleaches,
cleaning solvents, salts, air ffesheners, adhesives, paint, and
other household products. Locate combustion-air inlet as far
as possible from swimming pool and swimming pool pump
house,
FIRE AND EXPLOSION HAZARD
Failure to %llow this warning coutd result in fire, property
damage, persona! i11jury, or death.
Soh'ent 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
CARBON MONOXIDE POISONING HAZARD
Failure to %llow this warning could result in property
damage, personal injury, or death.
Ail combustion-air and vent pipes must be airtight and
watertight. Pipes must also terminate exactly as shown in Fig.
36, 37, 38, 39, or 40.
NOTE: The nlininmm combustion=air and vent pipe length (each)
for d-lose furnaces is 5 ft. Short pipe lengths (5=g ft) may discharge
water droplets These &oplets may be undesirable, and a 12-in.
minimum off:set pipe section is recommended, as shown in Fig. 34,
to reduce excessive droplets from exiting vent pipe outlet.
Combustion-Air and Vent Pipe Diameter
Determine combustion-air and vent pipe diameter.
1. Using Table 7, individoally detem_ine the smallest
combustion=air and vent pipe diameters permitted for each
pipe. Pick the larger of these 2 pipe diameters and use this
diameter for both combustion=air and vent pipes.
2 When installing vent systems of short pipe length, use the
smallest allowable pipe diameter. Do not use pipe size greater
than required or incomplete combustion, flame disturbance, or
flame sense tockout may occur.
NOTE: Do not count elbows or pipe sections in terminations or
within f'umace. See shaded areas in Fig. 36, 37, 38, 39, and 40.
25
To Next Page
Loading...
