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A. When installing two openings, one must commence
within 12 inches from top and other within 12
inches from bottom of enclosure. Openings shall
communicate directly, or by ducts, with outdoors
or spaces (crawl or attic) that freely communicate
with outdoors. One of following methods must be
used to provide adequate air for ventilation and
combustion.
1) When directly communicating with outdoors,
each opening shall have minimum free area of
1 square inch per 4,000 Btu per hour of total
input rating of all equipment in enclosure. Refer
to Figure 2 on previous page.
2) When communicating with outdoors by
means of vertical ducts, each opening shall
have minimum free area 1 square inch per
4,000 Btu per hour of total input rating of all
appliances in the enclosed space.
3) If horizontal ducts are used, each opening
and duct shall have minimum free area 1
square inch per 2,000 Btu per hour of total
input rating of all appliances in the enclosed
space.
!
WARNING
Vent connectors serving appliances vented by
natural draft shall not be connected into any
portion of mechanical draft systems operating
under positive pressure.
1.
The vent pipe must slope upward from the boiler
not less than 1/4" for every 1' to the vent terminal.
Figures 1 & 2.
2.
Horizontal portions of the venting system shall be
supported rigidly every 5 feet and at the elbows. No
portion of the vent pipe should have dips or sags.
Flue Connection And Venting
Vent installations shall be in accordance with "Venting of
Equipment", of the National Fuel Gas Code, ANSI Z223.1/
NFPA 54, or applicable provisions of the local building
codes.
1.
Consult dimensional drawing for number and size of
flue pipes required for each size boiler.
2.
Maintain minimum upward slope of 1/4 inch per linear
foot from the boiler to chimney.
3.
Run flue pipe directly as possible. Keep turns to a
minimum. Insert flue pipe into, but not beyond, inside
wall of chimney. Do not connect into a chimney serving
an open fireplace.
VENTILATION AND COMBUSTION AIR
VENT INSTALLATION
10
B. One permanent opening, commencing within 12
inches of top of enclosure, shall be permitted where
equipment has clearances of at least 1 inch from
sides, 1 inch from back, and 6 inches from front
of boiler. Opening shall directly communicate with
outdoors or shall communicate through vertical
or horizontal duct to outdoors or spaces (crawl
or attic) that freely communicate with outdoors.
Openings must have minimum free area of 1
square inch per 3000 Btu per hour of total input
rating of all equipment located in enclosure. Free
area must be no less than sum of areas of all vent
connectors in confined space.
6.
In calculating free area using louvers, grilles or
screens for above, consideration shall be given
to their blocking effect. Screens used shall not be
smaller than 1/4 inch mesh. If free area through
design of louver or grill is known, it should be used
in calculating size opening required to provide free
area specified. If design and free area is not known,
it may be assumed that wood louvers will have 20-
25% free area and metal louvers and grilles will
have 60-75% free area. Louvers and grilles should
be fixed in open position or interlocked with boiler
so they are opened automatically during boiler
operation.
4.
Insulate flue pipe where it passes near combustible
material.
5.
Rigidly support pipe with hangers and straps.
6.
Extend chimneys at least 2 feet above any object
within radius of 15 feet, including roof.
7.
Install hood on all flue pipes which extend through roof.
In most locations, venting of boiler relies on natural
draft. In as much as energy available from natural
draft is quite low, serious thought should be given to
vent system design, i.e., adequate size, use of gradual
transitions, tees, elbows, etc., close proximity of boiler
and chimney. On all boilers, vertical risers must be at
least as large as vent openings on draft-hood. Boiler
manufacturer makes no specific recommendations
regarding application of draft inducers that may be
used with this boiler. If draft inducer is used, it is up to
installing contractor and draft inducer manufacturer to
determine proper application.
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