16
I-OH (01-20) PN120390R7
INSTALLATION—CONTINUED
Venting and Combustion Air—Continued
Chimney—Continued
• Field-constructed metal chimney:
ensure that the vent pipe is as follows:
Minimum 7-inch (178-mm) diameter for unit size 095
Minimum 8-inch (203-mm) diameter for unit sizes 140 and 190
24-gauge or heavier triple-wall stainless steel (recommended) or 24-gauge or heavier galvanized steel
If the venting arrangement passes through a ceiling, triple-wall stainless vent pipe is required above the ceiling.
The point of passage through a ceiling must be guarded by a metal ventilated thimble not less than 12 inches
(305 mm) larger in diameter than the pipe.
Install a tee with a cleanout cap at the bottom of the vertical rise
• Dimensions:
ensure that the dimensions of the chimney are as follows:
Minimum 7-inch (178-mm) diameter for unit size 095
Minimum 8-inch (203-mm) diameter for unit sizes 140 and 190
Minimum of 3 feet (0.9 meters) above the highest point of exit where it passes through the roof
Minimum of 2 feet (0.6 meters) higher than any portion of a building within 10 feet (3 meters) of the chimney
Minimum of 8 feet (2.4 meters) total chimney height
• Draft:
the chimney must be capable of maintaining a steady draft of 0.04 IN WC. If the draft is below the
minimum required, a draft inducer must be installed.
• Vent connection from the flue outlet of the heater to the chimney:
ensure that the vent pipe is as follows:
Minimum 7-inch (178-mm) diameter for unit size 095
Minimum 8-inch (203-mm) diameter for unit sizes 140 and 190
24-gauge or heavier triple-wall stainless steel (recommended) or 24-gauge or heavier galvanized steel
Keep the length of the vent pipe connection as short and direct as possible
As it leaves the heater, slope the horizontal run upward at least 1 inch for each 3 feet of pipe. The horizontal run
should not be longer than one-half of the vertical or chimney height and never over 10 feet (3 meters) unless a
draft inducer is being installed.
• Vent pipe connector passes through a combustible wall:
vent pipe must be guarded at the point of passage
by either a metal ventilated thimble not less than 12 inches (305 mm) larger in diameter than the pipe or a metal
or burned fireclay thimble built in brickwork or other approved fireproofing material extending not less than 8
inches (203 mm) beyond all sides of the thimble. If a thimble is not installed, all combustible material in the wall or
partition must be cut away 9 inches (229 mm) from the pipe. If any material is used to close this opening, it must
be non-combustible.
• Fasteners and supports:
fasten all vent piping using sheet metal screws and support horizontal vent pipe from
above using noncombustible straps.
• Pipe runs:
avoid sharp turns in the vent pipe or other construction features that would create resistance to the
flow of the flue gases.
• Dampers:
do not use a manually operated damper or any other device that will obstruct the free flow of the flue
gases.
• Vent pipe connection inside chimney:
the end of the vent pipe connection must not extend past the inside wall
of the chimney. A thimble may be used in the chimney connection to facilitate removal for cleaning. The thimble
should be permanently cemented in place with high-temperature cement.
