For 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
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.
14
FIRING RATE
CHIMNEY
NOMINAL ROUND LINER- SQUARE LINER-
(gph)
HEIGHT (ft) CHIMNEY
INSIDE
INSIDE
0.60 - 1.30
15
8" x 8"
6"
6-¾" x 6-¾"
1.31 - 1.80
15
8" x 8"
7"
6-¾" x 6-¾"
1.81 - 2.00
20
8" x 8"
8"
6-¾" x 6-¾"
For elevations above 2,000 feet above sea level, add 3 feet to the chimney heights.
