Vent Connectors: From Heating Appliance to Chimney
Definition
Vent connectors are metal pipes that carry exhaust gases from an appliance to a chimney flue. They should be made of non-combustible, non-corrosive material that can withstand flue gas condensate and temperatures.
Installation
Vent connectors should rise at least 1/4 inch per foot. They should be supported with wire or strapping every 4 feet and the joints must be screwed together with sheet metal screws.
The joints should be aligned so that they will be liquid-tight or of a design that liquid will drain to the interior of the connector.
The horizontal run of the vent connector should be as short as possible and never more than 75% of the height. Longer vent connectors allow heat to dissipate, condensation to form and corrosion to accelerate.
Types of Vent Connectors
There are generally 3 types of vent connectors used in residential systems, but the overwhelming majority of them are single wall metal connectors.
Single wall metal connectors. Depending on the appliance and installation, clearance to combustibles should be 9 to 18 inches. If the listing of an appliance specifies a different clearance, the listed clearance applies.
Double wall, uninsulated, or “B” vent. Clearance to combustibles is typically 6 inches. “B” and “L” vents may be in accordance with the appliance and vent listing.
Double wall, insulated. Clearance to combustibles should be 1 or 2 inches, or as the appliance or vent listing allows.
(Type “C” vents will also have appliance and vent listings that will indicate the allowable clearances.)
