Watts G4000 FDA Part of the G4000 FDA Series Window Well Extension This 3 4 inch boiler pressure This 3 4 inch boiler pressure relief valve is used in hot water space heating boiler applications to protect against excessive pressure on all types of hot water space heating boiler equipment This 4 inch reduced pressure zone assembly backflow preventer helps prevent the reverse flow of fire protection substances and water of non potable quality from being pumped or siphoned into the potable water supply due to backsiphonage and or backpressure in accordance with national plumbing codes and water authority requirements Features Cast iron UPC 098268093155