They are used interchangeably in manufacturer catalogs

In total darkness

Frequent tripping is often caused by blocked flue vents

The Robertshaw 620-402 is rated for both 50Hz and 60Hz

Weil McLain 383-500-045 Assembly They are used interchangeably inThe Weil McLain 383 500 045 Ignitor Flame Rod Assembly is a precision engineered ignition electrode kit designed specifically for the Weil McLain Ultra Gas Boiler series. As a critical component in the combustion cycle, this dual purpose electrode facilitates both high voltage spark ignition and continuous flame rectification to ensure safe, efficient burner operation. This OEM kit is compatible with Ultra Series 3, 3UE, and CT gas boilers across all