DuraVent DuraTech is a double wall all-fuel chimney system with both U.S and Canadian approvals for specific applications. 16" DuraTech chimney is rated to 2100° and is tested to UL 103 HT standards. DuraTech is for use with wood stoves, fireplaces, furnaces, boilers, ranges, water heaters or other appliances fueled by wood, coil, oil or gas. DuraTech chimney systems are limited for sales to certified installers only.