Spence E 3 125 Valve 321702 401 Key Benefits Direct OEM Compatibility: Key Benefits Direct OEM Compatibility: Engineered as a drop in replacement for Sentronic and Sentronic+ systems Enhanced Safety: Includes a pressure sensing switch to ensure the fan is operational before the burner is allowed to fire This main valve typically requires a minimum differential pressure of 10 15 PSI across the seat to ensure the diaphragm can overcome the spring force and fully stroke the valve The Spence E 3 125 is a professional grade pilot operated main valve engineered for critical steam pressure regulation and temperature control applications in commercial and industrial piping systems