Replacing it with an automatic reset switch would bypass a critical safety protocol and create a hazardous condition if the underlying venting issue persists

this 1/2" immersion well ensures your controls receive the accurate temperature data required for efficient boiler cycling and system protection

check system flow requirements before installing in heat pump liquid lines

using the correct metering piston is essential to prevent floodback and ensure the longevity of the compressor

What does it mean if the status light isn't flashing

McDonnell & Miller FS4-3S Switch 320720-756 Replacing it with an automaticThe McDonnell & Miller FS4 3S (Part Number 114641) is a rugged general purpose liquid flow switch specifically engineered for high demand hydronic and industrial applications. This 1" NPT flow switch features a high grade stainless steel body and hardened stainless steel bearings to minimize friction and prevent mechanical failure in the field. Designed as the direct replacement for FS4 3S E, it integrates a Single Pole Double Throw (SPDT) snap switch