it may stay open and prevent the furnace from firing

or improper fan-to-motor spacing (typically requiring 2-1/8" clearance on specific models)

Use a multimeter to check for continuity across the terminals when the switch is cold

the door prevents accidental setting changes and protects the control interface from moisture and dust

this SPST (Single Pole Single Throw) switch provides the exact calibration required for high-duty cycle environments

Hydrolevel EW201 Electro-Well it may stay open andAs a seasoned technician, you know that a Hydrostat controller is only as good as its interface with the boiler water. The Hydrolevel EW201 Electro Well (Part Number 48 201) is the specialized 3 4" NPT immersion well required to unlock the Low Water Cut Off (LWCO) functionality on Fuel Smart Hydrostat models. Unlike standard brass wells that only transfer temperature, this Electro Well features a patented design with an integrated electrical insulator