Centrotherm Eco Systems, maker of polypropylene venting technology, reported that its InnoFlue-branded single wall, flexible and concentric vent systems have been tested and are now listed to UL 1738. To date, InnoFlue is the only plastic vent that has earned this listing under the only standard in the USA that is specifically designed to test and list vent systems for Category II & IV heating appliances. For further information, go to www.intertek.com or www.centrotherm.us.com.