N.Y.C. Admin. Code § 27-863: § 27-863 Chimney construction for low, medium, and high temperature equipment.

(a) Unlisted chimneys for low temperature equipment shall be constructed in accordance with table 15-4.

(b) Unlisted chimneys for medium temperature equipment shall be constructed in accordance with table 15-5.

(c) Unlisted chimneys for high temperature equipment shall be constructed in accordance with table 15-6.

Table 15-4 Low Temperature Chimney Construction

Material

Thickness

Lining Required

Type of Lining

Thickness

Air Space

Steel a

(for exterior chimneys)

b

1/8 in. for areas up to 7 sq. ft., 3/16 in. for areas up to 12.5 sq. ft., 1/4 in. for larger.

Not required

. . . .

. . . .

. . . .

Steel

a

(for interior chimneys)

No. 16 U.S. gauge for areas up to 155 sq. in., No. 14 U.S. gauge up to 200 sq. in., No. 12 U.S. gauge up to 255 sq. in., No. 10 U.S. gauge for greater areas.

Not required

. . . .

. . . .

. . . .

Brick, masonry units, or 8.

c

in stone

Full height from chimney base to 4 in. above chimney wall.

Clay flue lining meeting requirements of Reference Standard RS 15-4, with fire clay mortar or cement mortar equal to that of Type M or Ref. Std. RS 15-3, or a heatproof and acidproof flue lining joint cement.

Not less than 5/8 in.

Not less than 1/4 in. nor more than 3/4 in. between chimney walls and flue lining

Concrete

Radial Brick

6 in.

c

7 1/2 in.

ditto Full height from chimney base to 4 in. above chimney wall.

ditto Firebrick Type G, RS 15-6, 4 1/2 in. laid in medium refractory mortar, RS 15-7, or acid resistant brick Type H or L, Ref. Std. RS 15-8

ditto . . . .

ditto . . . .

Brick type H or L, RS 15-7

8 in.

Not required

. . . .

. . . .

. . . .

Notes for Table 15-4:

a. Metal Chimneys shall be riveted, bolted or welded construction and made gas tight.

b. Exterior metal chimneys shall be galvanized, or pained on the exterior surface with a heat resisting paint or be constructed of equal corrosion alloys.

c. In buildings in residential occupancy group J-3, of four stories or less, and in other buildings not over two stories high and not in high hazard occupancy group A, providing the flue areas are not more than 200 sq. in., the walls of masonry or concrete chimneys may be reduced to 4 in. with fire clay flue linings. Flue linings shall be set ahead of chimney walls, and carefully bedded in fire clay mortar or in cement mortar. Chimney walls shall be provided with mortar spacer ties every 10 ft. of height. Mortar ties shall not be continuous around the flue linings.

Table 15-5 Medium Temperature Chimney Construction

Material

Thickness

Lining Required

Type of Lining

Thickness

Air Space

Steel

Same as for low temp. chimney

Lining is required for full height of chimney

Incinerators only – Castable refractory Cl A, RS 15-5

2 in.

None required

Medium-duty fireclay refractory brick (ASTM C 64) or the equivalent laid in medium- duty refractory mortar (ASTM C 105) or the equivalent, RS 15-6

The lining shall be at least 2 1/2 in. thick for chimneys having a diameter or greatest cross- section dimension of 18 in. or less. The lining shall have a thickness of not less than 4 1/2 in. laid on a full bed for chimney having a diameter or greatest cross- section dimension greater than 18 in.

Table 15-6 High Temperature Chimney Construction

Material

Thickness

Lining Required

Type of Lining

Thickness

Air Space

Steel

Same as for low temperature chimneys

For full height of chimney

High-duty fireclay brick (ASTM C 64) or the equivalent not less than 4 1/2 in. thick laid on a full width bed in high-duty refractory mortar (ASTM C 105) or the equivalent, RS 15-6

4 1/2 inches

None required