Now available is the Z-Vent III special gas vent system, in diameters of 3, 4, 5, and 6 inches. Z-Vent is designed for condensing furnaces and boilers as well as high-efficiency furnaces, pool heaters, and unit and water heaters. According to the manufacturer, Z-Vent III has a unique snap connection pipe for quick and easy installation; no clamps or sealants are required because the pipe ends have a built-in silicone gasket seal.