Compatible Replacement: Furnace ignition control board compatible with Honeywell S8610U3009, S8610U1003, and Resideo systems (post-2018 models). Functionality: Manages ignition sequence, flame monitoring, and safety shutoff for intermittent pilot furnaces and residential boilers. Compatibility Note: Not for standing pilot systems, direct burner ignition, or non-rectification flame sensing applications. Installation: Wiring differs from older S86XXXX models—refer to documentation for TH-W/24V terminal connections. Universal Use: Works with natural or LP gas; includes part number S8610U for easy identification.