A.o. Smith 100109978 Ignitor Flame Sensor Btn Series

Product Description

The A.O. SMITH 100109978 is an OEM ignitor and flame sensor assembly designed for use in BTN Series commercial water heaters. The ignitor initiates combustion by generating a high-voltage spark to light the burner, while the integrated flame sensor confirms a stable flame is present and signals the control board to maintain the heating cycle. Loss of either function results in lockout and no hot water. Licensed service technicians install this component as part of routine maintenance or burner troubleshooting on BTN Series units.

This assembly is designed for the A.O. SMITH BTN Series, which includes the BTN 180 model referenced in the product identification. The BTN Series is a line of commercial gas-fired water heaters commonly found in light commercial and high-demand residential applications. This part is the appropriate replacement when the existing ignitor fails to spark or the flame sensor produces a weak or erratic signal causing nuisance shutdowns.

Key Features

• Combines ignitor and flame sensor functions in a single replacement assembly
• OEM part number ensures fit and function match to BTN Series specifications
• Restores proper ignition and flame verification to eliminate burner lockout
• Designed for commercial-grade BTN Series gas water heater applications

Compatibility

Designed for use with the A.O. SMITH BTN Series, including the BTN 180 model.

Installation Notes

Installation should be performed by a licensed plumber or qualified gas appliance service technician. Shut off the gas supply and disconnect power to the unit before removing the existing ignitor or flame sensor. Handle the flame sensor rod carefully to avoid contamination from skin oils, which can degrade sensing performance. Follow all applicable local codes and the manufacturer service documentation when reassembling the burner assembly.

Technical Specifications

• Compatible Series: BTN Series
• Component Type: Ignitor and Flame Sensor Assembly

Standard Information

• Brand: A.O. SMITH
• Manufacturer Part Number: 100109978