The storm collar is used to create a seal around the vent pipe and the firestop flashing or wall pass through. No collar is needed with the adjustable wall thimble. All pipe and fittings are UL1738 approved for category II, III and IV venting applications.
What is UL 1738? In short, it is a US standard for gas venting systems required in category III applications. Category III refers to positive vent pressure which is created by exhaust blowers in unit heaters. These vent systems must be constructed of AL29-4C® stainless steel, contain gaskets for sealing, and have a built in mechanical locking band among other requirements.
- Made of AL29-4C® super-ferritic stainless steel
- uilt-in locking band to insure a secure fit (no hardware needed)
- UL1738 approved for category II, III and IV appliances.
- Limited lifetime warranty
Item # VK 4650180, 4651180, 4651340