The Macon Controls T23000 Valve Insert (available in 1/2", 3/4", and 1") is a precision-engineered replacement cartridge for HVAC zone valve bodies that regulates fluid flow in hydronic heating and cooling systems. Installed within compatible zone valve assemblies, it modulates water or glycol flow to maintain desired temperatures and optimize system performance. Designed for use in r... https://www.partshnc.com/t23000-macon-controls-valve-insert-for-12-34-1