Among the more obvious reasons for the use of round duct on rooftops, such as preventing rain, snow and ice buildup, ease of wind passage is perhaps the most overlooked. PhenoliDuct, a new closed-cell insulated round duct solution from Spiral Pipe of Texas (SPOT), is engineered with all those considerations in mind, plus ease of installation.
In sum, if you have installed double wall spiral duct, you already know how to install PhenoliDuct. The rigidity of the phenolic board and the close tolerances of the duct’s annular construction eliminate the need for an inner coupling. Most installations will only need external bolted companion angle rings or flanges, according to SPOT.