Combustion Air Supply - Beckett NX Series Manual

Figure 2 – Chimney Design - Above the Roof
2. A chimney fl ue shall extend at least 3 feet above
the highest point at which the chimney comes
in contact with the roof, and not less than 2 feet
above the highest roof surface or structure within
10 feet horizontally of the chimney. Refer to
Figure 2.
3. Any accumulation of soot or debris in chimney
offsets should be removed
4. Any obstructions such as a protruding joint or
a piece of broken tile wedged in the chimney
should be removed.
5. No other appliance connection should be made
to the same fl ue pipe.
6. The fl ue pipe should have an upward pitch
toward the chimney of at least 1/4" per foot of
length. It should fi t tightly and should not project
into the chimney.
7. Any leakage between tiles, around clean-out
doors, or around the vent pipe should be sealed.
INSULATED STAINLESS STEEL CHIMNEY LINERS
The new designs of high effi ciency oil furnaces
and boilers in conjunction with fl ame retention oil
burners are more effi cient. One result of increased
effi ciency is lower fl ue gas temperatures. As
fl ue gases rise in the chimney, they will cool and
condense when they reach the dew point. The
condensation will mix with the sulphur in the fl ue
gases creating sulphuric acid. The acid will attack
the chimney mortar, brick and clay liners caus-
ing corrosion, deterioration and blockage of the
chimney. Eventually the blockage could prevent
exhausting the fl ue gases. Instead, the fl ue gases
could vent out the barometric damper into the liv-
ing space.
RWB 6104 WMNX
Inspect/Prepare Installation Site
Therefore, it is strongly recommended that an ap-
proved insulated stainless steel liner be installed.
• For those installations not requiring a chimney,
such as through-the-wall vented appliances, fol-
low the instructions given by the appliance and
power venter (if used) manufacturers.
Combustion Air Supply Information
•
Adequate Combustion
WARNING
!
and Ventilation Air Supply
Required
Failure to provide adequate air supply could se-
riously affect the burner performance and result
in damage to the equipment, asphyxiation, ex-
plosion or fi re hazards.
• The burner cannot properly burn the fuel if it is not
supplied with a reliable combustion air source.
• Follow the guidelines in the latest editions of the
NFPA 31 and CSA-B139 regarding providing ad-
equate air for combustion and ventilation.
See NFPA Standard 31 for complete details.
Appliances located in confi ned spaces: All
confi ned spaces should have two (2) permanent
openings; one near the top of the enclosure and
one near the bottom of the enclosure. Each open-
ing must have a free area of not less than one (1)
square inch per 1,000 BTU's per hour of the total
input rating of all appliances within the enclosure.
The openings should have free access to the
building interior, which should have adequate infi l-
tration from the outside.
NOTE: Correct
chimney design is
shown by dotted
lines. Incorrect
chimney design,
as shown by the
solid lines, may
result in down-
drafts.
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