System 636® Kit (UCVKTM Universal Concentric Vent ) The Universal Concentric Vent Kit (UCVKTM) is a versatile device allowing for compact space saving installations of tankless water heaters. It seamlessly transitions from vertical collars on the heater to a horizontal concentric vent for sidewall termination. System 636® UCVKs are engineered with an air intake hub, which pivots to accommodate the different spacing requirements between the fresh air and exhaust of tankless water heaters sold today. The innovative design optimizes productivity through ease of installation. The UCVK includes: A universal concentric vent kit body, Concentric vent pipe, and Rain cap. SYSTEM 636 UCVK in PVC: Suitable for use on appliances with flue gas temperatures up to and including 65°C (149°F). SYSTEM 636 UCVK in CPVC: Suitable for use on appliances with flue gas temperatures up to and including 90°C (194°F)