Masonry Chimneys
The minimum requirements for a properly constructed chimney include the following:
•The foundation must be large enough to support the intended chimney without settling.
•The masonry wall of the chimney, if brick or modular block, must be a minimum of 4" nominal thickness. A mountain- or
•The chimney must have a fireclay flue liner (or equivalent with a minimum thickness of 5/8" and must be installed with refractory mortar.There must be at1/ 2" air space between the flue liner and chimney wall.
•The preferred fireclay flue liner size has a nominal size of 8" x 8", and should not be larger than 8" x12". lf round fireclay liners are used, the inside diameter should be 6" and not larger than 8". lf an existing chimney with larger tiles is used it should be relined with an appropriate liner.
•No other appliance can be vented into the same flue.
•An airtight cleanout door should be located at the base of the chimney.
A chimney inside the house must have at least 2" of clearance to the combustible structure. A chimney outside the house must have at least 1" clearance to the combustible structure. Fire stops must be installed at the spaces where the chimney passes through floors and/or ceilings. Remember that there must be air space around the chimney, and that insulation must be 2" or more from the chimney.
A chimney, wether masonry or prefabricated metal, must be the required height above the roof or other obstruction for safety and for proper draft operation. The requirement is that the chimney must at least 3' higher than the highest point where it passes through the roof and at least 2' higher than the be at least and highest part of the roof or structure that is within 10' of the chimney, measured horizontally (fig. 4, page 21).
Chimneys shorter than 14' may not provide adequate draft. This could result in smoke spilling the room from the door or joints in the stove or pipe. In addition, inadequate draft can cause puffing. A
USA
Listed Metal Prefabricated Chimneys
The heater must be connected to a listed Type HT per UL 103 or ULC S629 prefabricated chimney.When a metal prefabricated chimney is used, the manufacturer's installation instructions must be followed precisely. You must also purchase (from the same manufacturer) and install the ceiling support package or wall pass through, the "T" section package, the firestops (when needed), the insulation shield, the roof flashing, the chimney cap, etc. Maintain the proper clearance to the structure as recommended by the manufacturer. This clearance is usually a minimum of 2", although it may vary by manufacturer or for certain components.
There are basically two methods of metal chimney installation. One method is to install the chimney inside the residence through the ceiling and the roof (fig. 5, page 22).
The other method is to install an exterior chimney that runs up the outside of the residence.
C. Connection to the Chimney
Masonry Chimneys
When connecting to a masonry chimney, the chimney connector must slide completely inside the chimney thimble (or breach) to the inner surface of flue liner, make sure the connector does not protrude past the inside of the flue liner as that will reduce the flow area available for the smoke and ultimately cause problems with your chimney system. The chimney connector should be sealed into the thimble with refractory cement and the connector should also be mechanically fastened to the chimney. See fig. 6, page 22.
Prefabricated Chimneys
Always follow the chimney manufacturer's instructions and use all the components required by the manufacturer. Do not take shortcuts or use make shift methods for securing the chimney connector to the chimney.
Note: The clearances expressed in inches are those approved for installations in the United States. The clearances in parentheses that are expressed in centimeters are those approved for installations in Canada. Different test standards for the respective countries may result in differences in the clearance requirements.
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