Sizing Guide

1
Venting Guidelines for Category I Gas Appliances
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
I. Single Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Notes for Single-Appliance Vent - Tables 1 and 2 . . . . . . . . . . . . . . . . . . .3
Table 1 - Single Appliance
(Capacity of Type B Double-Wall Vents when Connected Directly to a Single Appliance) . . . . .6
Table 2 - Single Appliance
(Capacity of Type B Double-Wall Vents with Single Metal Connectors) . . . . . . . . . . . . . . . .8
Examples Using Single-Appliance Venting Tables . . . . . . . . . . . . . . . . .10
II. Two or More Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Notes for Two or More Appliances - Tables 3 and 4 . . . . . . . . . . . . . . . .12
Table 3 - Two or More Appliances
(Capacity of Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving Two or More Category I Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Table 4 - Two or More Appliances
(Capacity of Type B Double-Wall Vents with Single-Wall Connectors
Serving Two or More Category I Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Examples Using Common Venting Tables . . . . . . . . . . . . . . . . . . . . . . . .19