What does the red color coding indicate on this limit switch

Look for physical bulging (domed top)

typically every 3 to 5 years depending on local water conditions

ensuring the control string remains stable during peak cycling

Weil McLain 383-500-628 Transformer What does the red colorThe Weil McLain 383 500 628 Transformer is a heavy duty, factory specified 120V to 24V step down transformer designed for critical power distribution within high efficiency hydronic systems. This 50VA boiler transformer provides a stable 24VAC secondary output, ensuring consistent low voltage signaling for the Weil McLain Ultra boiler control board and ignition sequences. As a direct replacement for the legacy 511 802 011, it is engineered to handle