Spirax-Sarco 55226 Main Valve 30067439-890 If you hear a humming

If you hear a humming sound or smell a metallic odor when the thermostat calls for heat

System Protection: Minimizes the risk of acid buildup and freeze-ups at the expansion device

Can I use an aftermarket universal switch instead of the York S1-373-03136-602

Is this part a direct substitute for the discontinued S1-36393846003

this Norton 41-602 igniter ensures rapid heat-up and long-term durability under harsh thermal cycling

Spirax-Sarco 55226 Main Valve 30067439-890 If you hear a hummingThe Spirax Sarco 55226 is a rugged 1 1 2" NPT main valve engineered for precision high capacity steam regulation. As the foundational component of the 25 series pilot operated regulator system, this cast iron valve body is rated for up to 250 psi and 450F, making it a standard for heating and process steam applications. Its normally closed design ensures a positive ANSI FCI 70 2 Class IV shut off, preventing steam leakage during dead end service. This