All installations and services must be performed by qualified service personnel.
plate is supplied with the furnace for adapting the 3-inch round flex combustion air duct to the 2-inch x 7-inch combustion air duct.
Recommended materials for the combustion air duct are smooth, round, galvanized steel duct or schedule 20 PVC pipe. The maximum intake duct length allowed is equivalent to
Optional combustion air - a 4” round duct may be used by connecting a 3 x 4 reducer to the 3” flex duct supplied with the furnace.
Figure 6
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