Common Venting Using Metal−Lined Masonry Chimney
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| SEALED | |
| MAX. LENGTH |
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| −− SEE NOTE 1 |
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5 ft. (1.5 m) | BELOW. |
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MIN. LENGTH −− AS |
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minimum | EXTERIOR | ||
SHORT AS PRACTICAL | |||
| CHIMNEY WITH | ||
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| METAL | |
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| LINER | |
VENT CONNECTOR |
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4 in. (102 mm) |
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minimum |
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| FURNACE |
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OTHER |
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APPLIANCE |
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| PERMANENTLY | |
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| SEALED FIREPLACE | |
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| OPENING |
NOTE 1 − Refer to the provided venting tables for installations. Refer to the capacity requirements shown in the provided venting tables.
FIGURE 24
DO NOT insulate the space between the liner and the chimney wall with puffed mica or any other loose gran- ular insulating material.
IMPORTANT
SINGLE appliance venting of a
A fan−assisted furnace may be commonly vented into an existing lined masonry chimney if the following conditions are met:
SThe chimney is currently serving at least one drafthood− equipped appliance;
SThe vent connectors and chimney are sized according to the provided venting tables.
If type B1
When inspection reveals that an existing chimney is not safe for the intended purpose, it shall be rebuilt to conform to nationally recognized standards, lined or relined with suitable materials, or replaced with a gas vent or chimney suitable for venting ML180UH series units. The chimney passageway must be checked periodically to ensure that it is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator, or flue restrictor between the furnace and the chimney. Never connect a Category I appliance to a chimney that is servicing a solid−fuel appliance. If a fireplace chimney flue is used to vent this appliance, the fireplace opening must be permanently sealed.
A type B or listed chimney lining system that passes through an unused masonry chimney flue is not considered to be exposed to the outdoors.
General Venting Requirements
Vent all ML180UH furnaces according to these instruc- tions:
1 − Vent diameter recommendations and maximum allow- able piping runs are found in the provided venting tables.
2 − In no case should the vent or vent connector diameter be less than the diameter specified in the provided venting tables.
3 − The minimum vent capacity determined by the sizing tables must be less than the low fire input rating and the maximum vent capacity must be greater than the high fire input rating.
4 − Single appliance vents − If the vertical vent or
5 − Multiple appliance vents − The flow area of the largest section of vertical vent or chimney shall not exceed 7 times the smallest listed appliance categorized vent area, drafthood outlet area or flue collar area unless de- signed according to approved engineering methods.
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