Venting and Combustion Air Inlet
A-General Recommendations and Requirements NOTE - The vent is a passageway, vertical or nearly so, used to convey flue gases from an appliance, or its vent connector, to the outside atmosphere. The vent connector is the pipe or duct that connects a fuel-gas burning appliance to a vent or chimney. The combustion air inlet is a pipe that connects the appliance to the outside atmosphere to convey oxygen from the air to the appliance burner.
Unit heaters must be vented in compliance with all local codes or requirements of the local utility, the current standards of the (American) National Fuel Gas Code, ANSI Z223.1 or (Canada) CSA-B149 Installation Codes, and the following instructions.
A vent connection flange and a combustion air pipe connection flange are attached to the back of the unit. Single wall vent material shall have all seams and joints sealed with pressure sensitive aluminum tape or silicone rubber sealant. Aluminum tape must meet the provisions of SMACNA AFTS-100-73 Standards. The aluminum tape has a temperature rating of 400°F (204°C). Silicone rubber sealant must have a temperature rating of 482°F (250°C), i.e., Dow Corning RTV-736 or equivalent. All joints shall be secured with at least two corrosion resistant screws. All joints must be checked for gas tightness after installation.
Single wall vent shall not pass through any attic, interior wall, concealed space, or floor.
B-Vertical Vents Using Metal Vent Pipe- Commercial and Residential Installations
These separated combustion unit heaters are listed as Category I appliances for vertical vent installations.
1-These unit heaters are to be vented with NFPA- or ANSI- approved chimneys, U.L. listed type B-1 gas vents, single wall metal pipe, or listed chimney lining system for gas venting where applicable, as well as the modifications and limitations listed in figure 2. Seal single wall vent material according to the section A-General Recommendations and Requirements. Air inlet pipe may be single wall metal pipe or U.L. listed single wall metal flex connector. A concentric vent/adapter/cap kit as specified in these instructions may be used for vertical termination. Refer to table 3.
2- The vent connector shall be 3" (76mm) diameter on 45 units, 4" (100mm) diameter on 60/75 units, and 5” (127mm) on 100/125 units. The air inlet pipe shall
be 3” (76mm) diameter on 45 units and 4” (100mm) diameter on 60/75/100/125 units.
3- Keep the vent and air inlet runs as short as possible with a minimum number of elbows. Refer to the (American) National Fuel Gas Code ANSI Z223.1 or (Canada) CSA-B149 Installation Code for maximum vent and vent connector lengths. Horizontal run of the vent connector from the induced draft blower to the chimney/vent cannot exceed the values in table 2. Single wall vent connector shall not be insulated.
4- If a single wall vent is used in an unheated area it shall be insulated with a minimum of 1/2" thick foil faced fiberglass 1-1/2# density insulation. Failure to do so will result in condensation of flue gases.
5- The unit may be vented vertically as a single appliance or as a common vent with other gas-fired appliances. In common venting situations, vent connectors for other appliances must maintain a 4" (100mm) vertical separation between the vent connectors. Refer to common venting tables in the (American) National Fuel Gas Code ANSI Z223.1 or (Canada) CSA-B149 Installation Code for proper vent size.
6- Clearance to combustible material is 6" (152mm) for single wall vent material except where a listed clearance thimble is used. Clearance to combustible material for type B-1 vent or factory-built chimney is per manufacturer’s instructions. Clearance to combustible material is 1” on vertical sections of the concentric vent/adapter/cap kit.
7- The vent connector shall be supported without any dips or sags. Vertical vents shall be supported in accordance with their listing and manufacturers’ instructions. All horizontal vent connector runs shall have a slope up to the vertical vent of at least 1/4" per foot (1mm per 50mm).
8- All vertical type B-1 vents, single wall vents, or listed chimney lining system must be terminated with a listed vent cap or listed roof assembly.
9- The vent must extend at least 3' (1m) above the highest point where it passes through a roof of a building and at least 2’ (0.6m) higher than any part of a building within a horizontal distance of 10' (3.05m) unless otherwise specified by the (American) National Fuel Gas Code, ANSI Z223.1 or (Canada) CSA-B149 Installation Codes. The vent must extend at least 5' (1.6m) above the highest connected equipment flue collar.
