Installation instructions
Masonry chimney
Masonry chimneys shall be built and installed in accordance with NFPS 211 or local codes. A minimum 5" diameter gas vent pipe (metal double wall Type B), or an approved clay flue liner or a listed chimney lining system must be used when venting into a naturally drafting, internal masonry chimney. 6 inch is required in elevations greater than 2000 feet, see Fig. 10. Local codes may require the use of both gas vent and an approved lining system when venting into a masonry chimney. The Commonwealth of Massachusetts requires the use of a listed liner. Lining systems include approved clay flue lining, a listed chimney lining system or other approved material that will resist corrosion, erosion, softening, or cracking from exhaust flue gases at temperatures up to 1800 degrees F. The lining
LOWEST DISCHARGE OPENING
H (minimum) height from roof to lowest discharge opening
LISTED GAS VENT
LISTED VENT CAP | |
X |
|
12 |
|
ROOF | MINIMUM 6 |
PITCH IS | |
X/12 | FEET (1.8M) |
system must be listed for use with naturally drafting, draft hood equipped gas appliances. Follow local codes and refer to NFGC 54 and NFPA 58.
Existing interior masonry chimney
The metal gas vent pipe should be permanently mounted inside the masonry chimney. Double wall Type B gas vent is recommended. The masonry chimney may have to be tile or metal lined before the insertion of the gas vent pipe; check local codes for clarification. The lining material must be listed for use only with naturally drafting, draft hood equipped gas appliances. Follow manufactures instructions for installation of listed lining material. You may not vent any other fuel burning appliances into any free space remaining in the chimney. The minimum vertical gas vent length within the masonry chimney should be no less than 6 ft (1.8 m); the vent terminator should extend at least 3 feet (0.9
m)above where the chimney meets the roofline and at least 2 feet (0.6 m) higher than any vertical wall or similar obstruction within 10 feet (3.1 m). The top of the gas vent should have an approved vent terminator. See Fig. 12.
ESTABLISH A ONE
FOOT RISE BEFORE
ANY ELBOWS
Fig. 11 Pitch roof
GAS VENT TERMINATIONS FOR LISTED VENT CAPS
Roof pitch | H (minimum) feet | meters |
Flat to 6/12 | 1.0 | 0.30 |
|
|
|
6/12 to 7/12 | 1.25 | 0.38 |
|
|
|
Over 7/12 to 8/12 | 1.5 | 0.46 |
|
|
|
Over 8/12 to 9/12 | 2.0 | 0.61 |
|
|
|
Over 9/12 to 10/12 | 2.5 | 0.76 |
|
|
|
Over 10/12 to 11/12 | 3.25 | 0.99 |
|
|
|
Over 11/12 to 12/12 | 4.0 | 1.22 |
|
|
|
Over 12/12 to 14/12 | 5.0 | 1.52 |
|
|
|
Over 14/12 to 16/12 | 6.0 | 1.83 |
|
|
|
Over 16/12 to 18/12 | 7.0 | 2.13 |
|
|
|
Over 18/12 to 20/12 | 7.5 | 2.27 |
|
|
|
Over 20/12 to 21/12 | 8.0 | 2.44 |
Table 2
| LISTED |
GAS | VENT CAP |
VENT |
|
VENT |
|
CONNECTOR |
|
Establish a |
|
one foot |
|
rise before |
|
any elbows |
|
Fig. 12 Masonry chimney
10 | 6 720 608 030 |