18-CG03D1-4
21
NOTE: This formula calculates the minimum inside
area of the chimney. If more than one appliance
vent connector pipe is connected to the chimney, the
minimum inside area of the chimney should be equal
to the area of the largest vent pipe plus one half the
area of any additional vent pipes. If the chimney is
too large or condensation has been a problem in the
past refer to the NFPA Standard for the Installation
of Oil Burning Equipment (NFPA31-most current
edition) Appendix E for proper liner sizing.
Chimney Height:
The chimney shall terminate at least 3 feet above the
highest point where it passes through the roof of a
building and at least 2 feet higher than any portion
of a building within a horizontal distance of 10 feet.
(See Fig. 13).
Proper chimney termination height
for pitched roofs
Figure 13
Chimney Inspection
The chimney, vent, or any passageway for the stack
gases to fl ow to the outdoor atmosphere is a very
important part of the heating system. No boiler,
regardless of the effi ciency of the design, can perform
satisfactorily when the chimney to which it is con-
nected is inadequate or in poor condition.
Any of the following symptoms may indicate a chim-
ney has severe structural damage and is unsuitable
for use:
- Chimney appears to be leaning to the side.
- Chimney appears to have structural damage, i.e.
loose or missing blocks or bricks, or excessive deterio-
ration at mortar joints.
- Tile liner damaged or missing.
- Flue gas leakage along the length of the chimney
between the chimney connector and discharge termi-
nation.
- Excessive corrosion at the cleanout port or at the
chimney connector entrance into the chimney.
- Structural debris, i.e. mortar or tile liner fl akes, in
base of the fl ue way.
A qualifi ed person shall inspect the chimney to con-
fi rm it is correctly sized for the application, properly
constructed, and in sound condition. Refer to the
Standard for the Installation of Oil-Burning Equip-
ment, NFPA 31-(most recent edition), for details on
proper chimney sizing and construction. If needed,
the chimney should be cleaned before installing the
boiler. Any accumulation of dirt or debris at the
bottom of the fl ue should be removed.
Chimney Sizing:
The boiler must be connected to an adequate chimney
or an approved vent in accordance with these instruc-
tions. An adequate chimney is one that is sealed
and lined with the capability of producing a (-).04”
WC fl ue draft and having the capacity to handle the
amount of stack gases that are introduced into it. A
chimney with an internal construction of corrosion
resistant tile, stainless steel, or some other material
that will withstand fl ue gas temperatures up to 900°F
is required.
The following are common chimney requirements
necessary for the boiler to operate correctly:
A masonry chimney serving an oil fi red boiler must
comply with local codes and NFPA Standard for
Chimneys, Fireplaces, Vents, and Solid Fuel Burning
Appliances (NFPA211-1996 or latest edition).
All installations and services must be performed by
qualifi ed service personnel.
The inside area of the chimney liner should equal, at
minimum, the area of the vent pipe exiting the boiler-
EXAMPLE:
π
x r
2
= Area of Pipe (sq. in.)
r = radius of pipe
π
=
3.1417
Flue Pipe Diameter = 6” [pipe Radius = ½
diameter of pipe = ½ ( (6 in.) = 3in.]
π
x 3
2
= 28 sq. in.
