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3 - Close all building doors and windows and all doors beĆ
tween the space in which the appliances remaining
connected to the common venting system are located
and other spaces of the building. Turn on clothes dryĆ
ers and any appliances not connected to the common
venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, so they will opĆ
erate at maximum speed. Do not operate a summer
exhaust fan. Close fireplace dampers.
4 - Follow the lighting instruction. Place the appliance beĆ
ing inspected in operation. Adjust thermostat so apĆ
pliance will operate continuously.
5 - Test for spillage at the draft hood relief opening after 5
minutes of main burner operation. Use the flame of a
match or candle, or smoke from a cigarette, or a cigar.
6 - After you have determined that each appliance reĆ
maining connected to the common venting system
properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers and
any other gas-burning appliance to their previous conĆ
dition of use.
7 - If improper venting is observed during any of the
above tests, the common venting system must be corĆ
rected. The common venting system should be re-
sized to approach the minimum size as determined by
using the appropriate tables in appendix G in the cur-
rent standards of the National Fuel Gas Code ANSI
Z223-1 in the U.S.A., and the appropriate Category 1
Natural Gas and Propane appliances venting sizing
tables in the current standards of the CAN/
CGA-B149.1 and .2 in the Natural Gas and Propane
Installation Code in Canada
.
Intake and Exhaust Piping Terminations
Intake and exhaust pipes may be routed either horizontally
through an outside wall or vertically through the roof. In at-
tic or closet installations, vertical termination through the
roof is preferred. Figures 8 through 20 show typical terĆ
minations.
1 - Use recommended piping materials for both intake
and exhaust piping.
2 - Secure all joints, including drain leg, gas tight using
approved cement.
3 - Piping diameters should be determined according to
length of pipe run. See table 4. Locate intake piping
upwind (prevailing wind) from exhaust piping. To avoid
re-circulation of exhaust gas on roof terminations, end
of exhaust pipe must be higher than intake pipe.
Exhaust and intake exits must be in same pressure
zone. Do not exit one through the roof and one on the
side. Also, do not exit the intake on one side and the
exhaust on another side of the house or structure.
4 - Intake and exhaust pipes should be placed as close
together as possible at termination end (refer to ilĆ
lustrations). Maximum separation is 3 inches (76mm)
on roof terminations and 6 inches (152mm) on side
wall terminations.
5 - Exhaust piping must terminate straight out or up as
shown. In rooftop applications, a 2 inch X 1-1/2 inch reĆ
ducer for 2 inch venting, 3 inch x 2 inch reducer for 3
inch venting must be used on the exhaust piping at the
point where it exits the structure to improve the velocity
of exhaust away from the intake piping.
On roof terminations, the intake piping should termiĆ
nate straight down using two 90° elbows (See figure 8).
IMPORTANT
Do not use screens or perforated metal in intake and
exhaust terminations. Doing so will cause freeze-
ups and may block the terminations.
NOTE - If winter design temperature is below 32°F (0°C),
exhaust piping must be insulated with 1/2 inch (13mm),
Armaflex or equivalent when run through unheated
space. Do not leave any surface area of exhaust pipe
open to out-side air; exterior exhaust pipe must be insuĆ
lated with 1/2 inch (13mm) Armaflex or equivalent. In exĆ
treme cold climate areas, 3/4 inch (19mm) Armaflex or
equivalent is recommended. Insulation on outside runs of
exhaust pipe must be painted or wrapped to protect inĆ
sulation from deterioration.
FIGURE 8
ROOF TERMINATION KIT
(15F75) LB-49107CC for 2 (51) Venting
(44J41) LB-65678A for 3 (76) Venting
UNCONDITIONED
ATTIC SPACE
1/2 (13) FOAM
INSULATION IN
UNCONDITIONED
SPACE
3 x 2 (76 x 51) OR
2 x 1-1/2 (51 x 38)
PVC REDUCER
3(76) MAX.
12 (305) ABOVE
AVERAGE SNOW
ACCUMULATION
3 (76) OR
2 (51) PVC
PROVIDE SUPPORT
FOR INTAKE AND
EXHAUST LINES
8 (203) MIN
Inches(mm)
NOTE - During extremely cold temperatures, below
approximately 20°F (6.67°C), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
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