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I or oil-fired boilers for connections to vents or chimneys, vent installations shall be in
accordance with applicable provisions of INSTALLATION OF OIL BURNING
EQUIPMENT, NFPA-31 - latest revision, and applicable provisions of local building codes.
CHIMNEY AND CHIMNEY CONNECTIONS
This is a very important part of your heating system. No boiler, however efficient its design, can perform
satisfactorily if the chimney that serves it is inadequate. Check your chimney to make certain that it is the
right size, properly constructed and in sound condition.
It is cheaper to rebuild a poor chimney than to pay excessive fuel bills. If yours is an old chimney, a new
steel liner or a new prefabricated chimney may be the best solution. The following chart shows
recommended minimum chimney sizes based on Table 3 and Figure 6 of the I=B=R Testing and Rating
Standard for Heating Boilers, Sixth Edition, June 1989.
RECOMMENDED MINIMUM CHIMNEY SIZES
NOMINAL ROUND LINER - SQUARE LINER -
FIRING RATE CHIMNEY
CHIMNEY INSIDE INSIDE
(gph) HEIGHT (ft) AREA DIAMETER I DIMENSIONS
0.60 - 1.30 15 8" x 8" 6" I 6-3/4" x 6-3/4"
1.31 - 1.80 15 8" x 8" 7" 6-3/4" x 6-3/4"
1.81 - 2.00 20 8" x 8" 8" 6-3/4" x 6-3/4"
:or elevations above 2,000 feet above sea level, add 3 feet to the chimney heights. See Figure below.
For additional chimney design and sizing information, consult the ASHRAE 1996 HVAC Systems and
Applications Handbook, Chapter 30, Gas Vent and Fireplace Systems; or the National Standard for
Chimneys, Fireplaces, Vents and Solid Fuel Burning Appliances, ANSI/NFPA 211.
CHIMNEY CONNECTOR AND DRAFT REGULATOR
Venting the boiler requires a 6" diameter chimney connector pipe and using the draft regulator packed with
the boiler. Properly installed, the regulator will control the draft automatically. It is better to install it in a
horizontal section of pipe, but it may be installed in an angled or vertical section of pipe. Make certain that
the "top" of the regulator is at the top - and that the short pipe section which holds the vane is horizontal.
Even though locating the draft regulator close to the chimney reduces noise, install the draft regulator as
close as practicable to the boiler.
To install the chimney connector, start at the boiler with a vertical pipe and then elbow - then install the draft
regulator making it horizontal. When the regulator is in place, start at the chimney and work back to the
regulator. Join the two sections with a drawband. The horizontal pipe must slope up toward the chimney at
least 1/4 inch per linear foot of venting. The chimney connector must not leak and must be firmly supported.
Join each of the sections with at least two sheet-metal screws. Support every second section with a stovepipe
wire.
Maintain a minimum vent pipe clearance of 18" from the surface of the vent to wood and other
combustible materials.
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