For larger Knight XL or Crest series

or if you see a diagnostic code indicating a pressure switch circuit error

provided the mechanical valve body matches the coil’s mounting stem

The 571110LF-345 serves as the direct lead-free replacement for the discontinued 571110-345 model

Resideo PV075S Eliminator 321042-401 For larger Knight XL orThe Resideo PV075S Eliminator is a high performance 3 4 inch sweat power vent designed for critical air management in hydronic heating systems. Engineered for efficient microbubble removal, this unit utilizes an internal stainless steel concentric coalescing medium to break surface tension and release trapped air from the system fluid. By maintaining a deaerated system, the PV075S prevents oxygen related corrosion and ensures optimal heat transfer