Raypak 007374F - Hot Surface Ignition Module

The Raypak 007374F Hot Surface Ignition (HSI) Module is an authentic OEM electronic control engineered to govern safe, reliable ignition sequences in Raypak commercial boilers and hydronic heating equipment. Operating on a standard 24VAC circuit, this Fenwal-based control board (cross-reference 35-673902-561) precisely coordinates igniter warm-up, gas valve actuation, and continuous flame rectification monitoring. Installing this factory-specified board eliminates intermittent ignition lockouts, restores rapid heating response, and preserves system safety standards.

• Direct OEM Replacement: Matches factory specifications for select Raypak hydronic boilers and volume water heaters, directly replacing Fenwal model 35-673902-561.
• Precise 24VAC Sequence Control: Microprocessor-driven circuitry governs igniter warm-up and gas valve timing to ensure smooth, efficient burner light-offs.
• Integrated Flame Rectification: Continuously monitors burner flame current to trigger an immediate, safe fuel shutoff in the event of flame failure.
• Durable Solid-State Design: Built to withstand the continuous operational demands, thermal cycling, and electrical conditions of commercial mechanical rooms.