Zilmet USA has introduced the new ZEP-1 Stainless Steel Expansion Tank and Shock Arrester for tankless and POU water heaters with two gallons or less of total water volume. Most tankless water heater manufacturers require a thermal expansion tank with their water heaters when a backflow preventer is required. The compact ZEP-1 is the perfect solution for providing thermal expansion protection in tight places. It features stainless steel construction and is NSF 61 certified.