Z-Flex Z-Vent 3" Vertical Condensation Drain Tee (2SVEVWCF03). This is the best piece to use as a condensation drain point for all vertical venting installations. This drain tee acts as a 90 degree angle, but it has a reservoir and a drain point to easily remove rain water and condensation that may come down the exhaust system. Z-Flex Z-Vent stainless steel vent pipe is ideal for the Bosch Therm 940ES / Bosch Therm 830ES / Bosch Therm 660EF / Bosch AquaStar 2700ES / Bosch AquaStar 2400ES / Bosch Evolution 500 tankless water heaters as well as the legacy Bosch Pro 715ES / Bosch Pro 635ES / Bosch AquaStar 2400E / Bosch AquaStar 250SX heaters. Z-Flex Z-Vent is rated AL29-4C and is approved for Category I (vertical only), II, III & IV applications and is designed for use with boilers, high efficiency gas and oil heaters and water heaters where cool flue gases are vented under pressure. Z-Vent contains a built-in, fail-safe gasket and locking band connection. No sealant is required.