the MARS 61472 is specifically designed for three-phase loads

The McDonnell & Miller 354140 is a high-precision PA-800-RX2 replacement probe engineered for field-service reliability in low water cut-off (LWCO) applications

it is likely not detecting a flame

63-inch diameter shaft

which allows for rapid access to the 100 mesh stainless steel screen without disturbing pipe connections

Robertshaw 5500-213M Switch 318973-401 the MARS 61472 is specificallyThe Robertshaw 5500 213M Infinite Switch is a heavy duty, voltage sensing replacement control engineered for precision management of resistive loads in industrial and commercial heating equipment. As a direct M Series 240V infinite switch upgrade, this unit replaces the discontinued VSI (INF) models and the Robertshaw 5500 213. It features a 22. 5% low end input capability, making it ideal for applications requiring consistent, proportionate heat