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CHIMNEYS-GENERAL
The chimney is one of the most important parts
of your installation. Great care should be taken
to assure that the chimney you use is adequate
for the job.
No other appliances may vent into the same
flue as your furnace. There are several
reasons for this.
1. Air leaking into the flue through other
appliances will tend to reduce chimney draft
and result in poor combustion.
2. Air leaking into the flue will also tend to cool
the chimney and encourage greater creosote
production.
3. Creosote production may begin to block the
flue to the point that adequate draft for other
appliances is not provided thereby allowing
poisonous gases to enter the living quarters.
4. In the event of a chimney fire, the connection
of other gas or oil fired appliances will
prohibit shutting down the supply of oxygen
to the fire, thus letting the fire burn out of
control.
• The chimney must be a tile-lined masonry
(brick or block) or metal, laboratory approved,
Class "A" all fuel chimney.
• The minimum net flue size must be a least 6"
diameter or 6" x 6" square.
• The exterior clearance from the chimney to
any combustibles such as wood framing must
be a least 2" or in accordance with local
codes.
• To provide adequate draft, a minimum
chimney height of at least 20' is suggested. A
draft of .02" of water should be sufficient.
• The chimney must extend at least 3' above
the highest point where it passes through the
roof, and at least 2' higher than any part of
the roof within 10' of it. See Figure 1.
Required Chimney Height Above Roof
3' Minimum
above roof
surface at
3'
chimney
EXISTING CHIMNEYS
If you choose to use an existing chimney,
besides meeting the criteria in Chimneys-
General, have a professional inspect the
chimney for such problems as:
1. Leaks
2. Unsafe breeching from previous installation
3. Broken liner and
4. Obstructions
Remember, a chimney in poor condition is an
extremely dangerous fire hazard. Have any
problems properly repaired before attempting to
use the chimney.
10'
2' Minimum (height
above any roof
2'
surface within 10'
horizontally)
2" clearance between
chimney and combustibles
FIGURE 1
Page 2
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