Supco FLS401 Flame Sensor Hsi Furnace Replacement

Product Description

The Supco FLS401 is a replacement flame sensor designed for gas furnaces that use hot surface ignition (HSI) or direct spark ignition systems. The flame sensor monitors the burner flame during operation and sends a signal to the control board confirming ignition. If no flame is detected, the control board shuts off the gas valve to prevent unsafe conditions. This part is installed by licensed HVAC technicians during routine maintenance, no-heat diagnostics, or control system repairs. The FLS401 measures 0.87 inches by 0.75 inches by 35.24 inches and is engineered by Supco as a broad-compatibility replacement for common OEM sensors.

This flame sensor fits gas furnaces equipped with hot surface ignition or direct spark ignition systems. It is suited for residential heating applications where the original flame sensor has failed, causing nuisance lockouts, no-heat calls, or fault codes related to flame sensing. Technicians typically encounter a failed flame sensor when the furnace lights briefly and then shuts down on flame-loss fault. The FLS401 is positioned as a service-stock replacement covering a wide range of popular furnace models across multiple manufacturers.

Key Features

• Compatible with hot surface ignition (HSI) and direct spark ignition systems
• Functions as both a spark ignition interface and flame sensing rod
• Designed and engineered by Supco for broad OEM replacement coverage
• Compact form factor: 0.87 inches x 0.75 inches x 35.24 inches
• Suitable for residential gas furnace service and repair

Compatibility

Designed as an OEM-style replacement flame sensor for residential gas furnaces using hot surface ignition or direct spark ignition systems across many popular furnace brands and configurations.

Installation Notes

Flame sensor replacement is performed by a licensed HVAC technician. Before service, shut off power to the furnace at the disconnect switch and close the manual gas shutoff valve. The sensor mounts in the burner assembly and connects to the control board via a single lead wire. Follow all local codes and the furnace manufacturer's service instructions when performing ignition system repairs.