Description
The Fenwal 35-665938-215 is a versatile and reliable Hot Surface Ignition (HSI) control board designed for use in gas-fired heating systems, furnaces, boilers, and other HVAC equipment. Built by Fenwal Controls, this ignition module uses microprocessor-based technology to manage the entire combustion sequence — from pre-purge and ignition timing to flame sensing — helping ensure safe and efficient burner operation.
Key Features
- Microprocessor-based HSI control for precise ignition and purge sequencing.
- 120/240 VAC compatibility makes it suitable for a range of HVAC and burner systems.
- Pre-purge, inter-purge, and flame sensing for safe and efficient operation.
- Diagnostic LED and test pins simplify service and troubleshooting.
- Designed to support natural gas, propane, and manufactured gas applications.






