at the chimney for any indications of a prob-lem.
Once inside the structure, the inspection
should continue.
Among the more common indications that a
chimney needs repair/relining are:
• Leaning chimneys—Such a chimney is
clearly in need of a major repair. The appliance
that is venting into this chimney should be shut
down until a repair or replacement is complet-ed.
Figure 21.
• Chimney crown damage—Crown damage
due to freeze/thaw cycling is the most common
damage. The outdoor chimney crown is a good
indicator of chimney condition. Figure 22.
• Loose bricks and/or mortar—This in-dicates
condensate damage to the masonry
chimney; in such cases, relining is necessary
to prevent further damage to the vent system.
Figure 23.
• White powder (efflorescence) on exterior
brick surfaces—Figure 24 shows efflorescence
—salt deposits being driven from the chim-ney’s
bricks due to flue gas condensate.
• Moisture on the exterior walls of the
chimney—Figure 25 shows moisture and efflo-rescence
at the roofline due to condensation.
• Moisture or stains on interior walls near
the chimney—Figures 26 show plaster that fell
off interior walls due to condensate.
• Visual evidence of damage—This severe
damage includes missing, broken, cracked
and separated tile—and warrants shutting the
system down. Figure 27.
• Debris in the cleanout—Mortar, tile liner
and flakes are a clear indicators that the chim-ney
needs repair or relining. Figure 28.
22 National Oilheat Research Alliance
• Misaligned terra-cotta tiles at the joints—
In addition to the misalignment, Figure 29
shows a liner with missing, broken, cracked
and flaking tiles.
• No liner installed —Oilheat systems
should NOT be connected to a chimney with-out
a liner. Figure 30.
Steps to Take Installing a New
Oilheat System into a Chimney
Chimney inspection
NORA recommends that chimney cleanings
and inspections be performed before a new
high efficiency Oilheat appliance is installed to
replace an older unit.
The inspection should include the following:
• If there is a clean-out door, make sure
that it is shut tight and sealed.
• Observe the exterior of the chimney. If
it is damaged, deteriorating or leaning to one
side, further inspection by a chimney profes-sional
should be recommended.
• Remove the flue pipe from the chimney
breech and inspect the inside of the chimney
with a light and a flame mirror for signs of
damage or deterioration.
Even if the chimney inspection shows that
there are no problems, remember that the
gross flue gas temperatures for high-efficiency
systems range from about 300°F–500°F at
the outlet of the unit. These temperatures are
reduced before reaching the chimney because
of heat loss from the flue pipe and dilution air
from the draft regulator. The resulting flue gas
temperatures are usually insufficient to sustain
adequate draft in an older, oversized masonry
chimney and they allow condensate to form in
the chimney.