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§1559.18
<br />DWELLING HOUSE CODE
<br />tion is specifically approved by the Building
<br />Official.
<br />(b) At partitions. Smoke pipes shall not
<br />pass through combustible partitions unless
<br />protected by double metal ventilated thim-
<br />bles at least 12" larger in diameter than the
<br />pipe or protected by a metal thimble at least
<br />8" larger in diameter than the pipe with the
<br />space between the thimble and the pipe filled
<br />solidly with mineral wool or other approved
<br />noncombustible material and the outside
<br />surface of the thimble distant at least 2"
<br />from combustible material.
<br />(c) Combustible and protected materials.
<br />The clear distance in all directions between
<br />the smoke pipe and combustible material or
<br />construction including plaster on a combus-
<br />tible base shall be not less than 12". This
<br />clearance may be reduced to 6" where (i)
<br />such construction is protected by cement
<br />asbestos board not less than 1/a" thick or
<br />equivalent covering extending the full length
<br />of the smoke pipe and not less than 12" be-
<br />yond it on both sides with a minimum clear-
<br />ance space of r/4" between the asbestos board
<br />and combustible material, or (ii) where such
<br />construction is protected by plaster on metal
<br />or wire lath or gypsum lath, or (iii) where
<br />the smoke pipe is encased in approved in-
<br />sulating material not less than s/4 ~ thick.
<br />Lesser distances may be approved by the
<br />Board of Building Code Appeals when it has
<br />been established by test to its satisfaction
<br />that lesser distances will not be hazardous.
<br />1559.18 Clearances for gas vent connectors.
<br />Gas vent connectors shall be installed.with
<br />a clearance from unprotected combustible
<br />material or construction of not less than 6"
<br />for flue gas temperatures of 550 F or less, and
<br />not less than 9" for rated flue gas tempera-
<br />tures over 550 F. Where such combustible
<br />material or construction is protected in the
<br />manner specified in paragraph (c) of Section
<br />1559.17, the clearances shall be not less than
<br />3"for flue gas temperatures up to 550 F and
<br />not less than 6" for rated flue gas tempera-
<br />tures over 550 F.
<br />1559.19 Firestopping.
<br />All spaces between the masonry of chim-
<br />neys and wood joists, beams, or headers shall
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<br />be firestopped by filling with mortar or plas-
<br />ter not less than s/4" thick held by strips of
<br />metal lath or wire fabric secured to the
<br />chimney or to the framing, or by the use of
<br />other approved noncombustible materials so
<br />installed that the temperature of the face of
<br />the material in contact with combustible
<br />framing members shall at no time exceed
<br />190 F.
<br />1559.20 Sizes of flues and gas vents.
<br />(a) Liquid or solid fuel-fire appliances.
<br />The cross-sectional areas of flues for liquid
<br />or solid fuel-fired appliances shall be de-
<br />signed and proportioned to meet the condi-
<br />tions of temperature within and outside the
<br />flue, volume of flue gas, coefficient of heat
<br />transmission of chimney and flue construc-
<br />tion, exposure, shape and height of flue and
<br />other influences in accordance with accepted
<br />engineering practice. In the absence of satis-
<br />factory engineering design data, the mini-
<br />mum areas of flues for liquid or solid fuel-
<br />fired,appliances shall be:
<br />i. 57 square inches for warm air and hot
<br />water furnaces, steam and vapor heating
<br />appliances with not more than 15 psi gage
<br />pressure, and
<br />ii. 35 square inches for ordinary stoves,
<br />ranges and room heaters.
<br />(b) Gas-burning heat appliances. The
<br />cross-sectional areas of flues for gas-burning
<br />heat appliances with natural draft venting
<br />shall be not less than that determined from
<br />the following Chart. When more than one
<br />heat appliance connects into a flue, the area
<br />of the flue shall equal the area of the largest
<br />gas vent connector plus not less than 50 per
<br />cent of the areas of the additional gas vent
<br />connectors.
<br />1559.21 Maintenance.
<br />All chimneys, flues, smoke pipes, and gas
<br />vents shall be maintained in a safe and gas-
<br />tight condition and the Building Official may
<br />prohibit the use of any appliance or device
<br />connected to any chimney, flue, smoke pipe,
<br />or gas vent not so maintained. Any chimney;
<br />flue, or gas vent which becomes unsafe or
<br />dangerous shall be made safe and acceptable
<br />to the Building Official or be taken down. .
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<br />Chimneys, Flues and Gas Vents
<br />§ 1559.09
<br />(g) Two openings. A flue may have
<br />openings for connections in more than one
<br />story only when the area of such flue is
<br />deemed by the Building Official to be suf-
<br />ficient to serve all connected heat appli-
<br />ances, provided such connections conform to
<br />Section 1559.05.
<br />1559.08 Type A flues.
<br />(a) Qualifications. In lieu of chimneys
<br />serving low-temperature appliances, flue as-
<br />semblies of materials approved by the Board
<br />of Building Code Appeals may be used, pro-
<br />vided further that:
<br />i. The assembly is noncombustible and
<br />gas-tight; '
<br />ii. Portions exposed to the weather or to
<br />condensed moisture are corrosion-resistant;
<br />iii. Lining surfaces that come in contact
<br />with flue gases are acid-resistant;
<br />iv. The assembly and its supports are
<br />structurally sound and durable; and
<br />v. The assembly successfully passes the
<br />fire-hazard test specified in the following
<br />paragraph (b) or a test accepted as equiva-
<br />lent by the Board of Building Code Appeals.
<br />(b) Fire-hazard test for Type A flues.
<br />Any Type A flue proposed for use shall be
<br />subjected to the following test:
<br />1. The flue assembly shall be installed, in
<br />accordance with the manufacturer's instruc-
<br />tions, in a frame structure simulating an
<br />actual installation.
<br />2. The lower end of the flue shall be con-
<br />nected directly to the vent of a suitable
<br />heater.
<br />3. A pilot thermocouple shall be installed
<br />in the center of the flue at the ceiling level
<br />of the frame structure.
<br />4. Additional thermocouples shall be lo-
<br />cated at stations on (i) the inside of the flue,
<br />(ii) the outer surface of the flue, and (iii)
<br />adjacent wood surfaces.
<br />5. The heating device shall be regulated to
<br />produce a temperature of 1000 F at the pilot
<br />thermocouple within 5 minutes and then
<br />maintained until temperatures stabilize.
<br />During this period, temperatures on the
<br />wood surface shall not exceed 160 F; or 90 F
<br />above roam temperature, and combustible
<br />materials in contact with the flue shall not
<br />ignite.
<br />6. The temperature at the pilot thermo-
<br />couple shall then be raised to 1400 F within
<br />5 minutes and maintained the remainder of
<br />an hour and then subsequently raised to 1700
<br />F and maintained for 10 minutes.
<br />Wood surfaces and combustible material
<br />in contact with the flue shall not ignite or ap-
<br />proach ignition temperatures.
<br />During the test, no cracks, falling, or dis-
<br />ruptive effects prejudicial to the stability,
<br />durability, or continued safe use of the flue
<br />shall occur. The flue shall remain gas-tight.
<br />There shall be no melting or blistering of the
<br />lining in contact with flue gases. All parts of
<br />burnt-clay lining shall remain in place.
<br />(c) Acceptance of Type A flues. Flue
<br />assemblies listed by the Underwriters'
<br />Laboratories, Inc. as suitable for use with
<br />low-temperature appliances, or tested and
<br />approved by other accredited testing agen-
<br />cies as meeting the requirements of this
<br />Dwelling House Code for Type A flues, shall
<br />be deemed to be accepted by the Board of
<br />Building Code Appeals for installation in
<br />compliance with the conditions of such list-
<br />ing or approval, unless and until by formal
<br />action said Board disapproves the same.
<br />1559.09 Type B gas vents.
<br />(a) Type B gas vents shall be of noncom-
<br />bustible, corrosion-resistant material ap-
<br />proved,by the Board of Building Code Ap-
<br />peals as having sufficient strength, cross-
<br />sectional area and heat insulating value to
<br />operate with flue gas temperatures of 550
<br />F without causing temperatures in excess of
<br />190 F on combustible surfaces 1 inch from
<br />the exterior surface of the gas vent. Type
<br />B gas vents, which have been listed by the
<br />Underwriters' Laboratories, Inc. or other
<br />accredited testing agencies as meeting the
<br />requirements herein specified, may be ac-
<br />cepted by the Building Official without fur-
<br />ther test.
<br />(b) Type B gas vents shall have bell and
<br />spigot, socket, crimped or other acceptable
<br />.joints which shall be made gas-tight with
<br />acid-resistant mortar or compound, or other-
<br />wise sealed in a manner satisfactory to the
<br />Building Official.
<br />(c) Type B gas vents may be used with
<br />gas appliances which produce flue gas tem-
<br />peratures not in excess of 550 F at the out-
<br />let of the draft hood,when burning gas at the
<br />manufacturer's input rating.
<br />(d) Provision satisfactory to the Building
<br />Official shall be made to prevent mechanical
<br />injury to Type B gas vents where they ex-
<br />tend through the walls, floors or roofs.
<br />(e) Type B gas vents shall be supported
<br />and braced on corrosion-resistant brackets
<br />or hangers satisfactory to the Building Of-
<br />ficial.
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