Honeywell ST7800A1039 Purge Timer Card 30 Second

The Honeywell ST7800A1039 is a plug-in purge timer card designed to provide a fixed 30-second prepurge cycle for gas burner control systems. It is a non-programmable, plug-in module that installs directly into the timer card compartment of compatible Honeywell 7800 Series relay modules, supporting commercial furnace, boiler, and gas burner applications running on natural gas. The card governs the prepurge timing function required for proper combustion safety sequencing before ignition. This card is an OEM replacement component for Honeywell 7800 Series systems and is compatible with Honeywell equipment only. It is used to restore or maintain correct purge cycle operation where symptoms such as burner not igniting, ignition lockout, safety interlock failure, or improper purge timing are present. Installation is DIY-friendly, requiring only removal and replacement of the plug-in card in the relay module. Carries a 1-year warranty; not hazmat or A2L classified.