Ao Smith 100110355 Hot Surface Ignitor FPSH-40/50 FPST-50

Product Description

The AO SMITH 100110355 is a replacement hot surface ignitor designed for use in AO SMITH water heater models. The hot surface ignitor is a critical ignition component that generates the heat needed to ignite the gas burner in a standing-pilot-free ignition system. When the ignitor fails, the burner will not light and hot water production stops. This OEM-style replacement restores reliable ignition performance. It is installed by licensed plumbers and HVAC technicians as a standard service part during water heater maintenance or troubleshooting calls.

This ignitor is intended for residential water heater applications. It is specified for use on AO SMITH FPSH-40, FPSH-50, and FPST-50 model water heaters. Techs typically encounter this part when diagnosing a no-heat or no-ignition condition on these units. Replacing a failed hot surface ignitor is a straightforward service task once the unit is properly shut down and the burner assembly is accessed.

Key Features

• Direct replacement ignitor for specified AO SMITH water heater models
• Restores burner ignition function without modification
• OEM-style fitment for FPSH-40/50 and FPST-50 units
• Eliminates standing pilot — part of an electronic ignition system

Compatibility

Compatible with AO SMITH FPSH-40, FPSH-50, and FPST-50 water heater models as a direct replacement ignitor.

Installation Notes

Installation should be performed by a licensed plumber or qualified HVAC technician. Before servicing, shut off the gas supply to the water heater and allow all components to cool completely — hot surface ignitors reach extreme temperatures during operation and can cause burns if handled immediately after use. Handle the ignitor element carefully, as the ceramic and silicon nitride materials are brittle and can crack if dropped or over-tightened. Follow local codes and the manufacturer service documentation when reassembling the burner assembly.

Technical Specifications

• Application: Replacement Part
• Compatible Models: FPSH-40, FPSH-50, FPST-50

Standard Information

• Brand: AO SMITH
• Manufacturer Part Number: 100110355