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Installation and
Service Manual
11
Exhaust Fans
Any fan or equipment which exhausts air from the boiler room
may deplete the combustion air supply and/or cause a down
draft in the venting system. Spillage of flue products from the
venting system into an occupied living space can cause a very
hazardous condition that must be immediately corrected. If a
fan is used to supply combustion air to the boiler room, the
installer must make sure that it does not cause drafts which
could lead to nuisance operational problems with the boiler.
Vertical DirectAire™ and Horizontal DirectAire™ venting
systems have specific requirements for combustion air ducts
from the outside which are directly connected to the unit. See
the requirements for combustion air duct in the venting
section.
VENTING
General Information
You must supply adequate combustion and ventilation air to
this unit. You must provide minimum clearances for the vent
terminal from adjacent buildings, windows that open, and
building openings. Follow all requirements set forth in the
latest edition of the National Fuel Gas Code, ANSI Z223.1, in
Canada, the latest edition of CAN/CGA Standard B149
Installation Code for Gas Burning Appliances and Equipment
or applicable local building codes. Vent installations for
connection to gas vents or chimneys must be in accordance
with Part 7, “Venting of Equipment” of the above-mentioned
standards.
Venting Support
Support horizontal portions of the venting system to prevent
sagging. Provide an upward slope of at least 1/4 inch per foot
(21mm/m) on all horizontal runs from the unit to the vertical
flue run or to the vent terminal on sidewall venting
installations.
Do not use an existing chimney as a raceway if another
appliance or fireplace is vented through the chimney. The
weight of the venting system must not rest on the unit. Provide
adequate support of the venting system. Follow all local and
applicable codes. Secure and seal all vent connections. Follow
the installation instructions from the vent material
manufacturer.
Vertical Vent Termination Clearances
and Location
The vent terminal should be vertical and exhaust outside the
building at least 2 feet (0.61m) above the highest point of the
roof within a 10 foot (3.05m) radius of the termination.
The vertical termination must be a minimum of 3 feet (0.91m)
above the point of exit.
A vertical termination less than 10 feet (3.05m) from a parapet
wall must be a minimum of 2 feet (0.61m) higher than the
parapet wall.
You must locate the air inlet termination elbow at least 12"
(30cm) above the roof or above normal snow levels.
Keep the vent cap clear of snow, ice, leaves, and debris to
avoid blocking the flue.
FIG. 10 Vent Termination from Peaked Roof - 10’ or Less
From Ridge
10' OR LESS
RIDGE
CHIMNEY
3' MIN.
2' MIN.
IMPORTANT: Examine the venting system at
least once each year. Check all joints and
vent pipe connections for tightness. Also
check for corrosion or deterioration. If you
find any problems, correct them at once.
IMPORTANT: Vent terminations are not shown
in Figures 10, 11, 12, and 13. Make sure all
vertical vents are installed with vent
terminations recommended by the vent
manufacturer.