This part is out of stock right now, so it cannot be added to the cart.
When the heating cycle starts, the igniter warms up to light the incoming gas. If this component wears out or breaks, the equipment will attempt to start but will fail to produce a flame.
Specifications
- Part number: 100271888
- Brand: A.O. Smith
- Part type: Igniter
- Height: 0.8 in / 2.03 cm
- Length: 11.45 in / 29.08 cm
- Width: 11.35 in / 28.83 cm
- Volts: must be the same, often 120 V
- Material: silicon carbide or nitride, as listed
- Shape and mount: must fit the same bracket
From the maker's and parts sellers' listings for this number. Compare them with the label on your old part.
How the Igniter Works
An igniter serves as the heat source that lights the gas burner. When your unit calls for heat, electric current flows through the igniter until it glows hot enough to safely ignite the gas supply.
Because igniters face extreme heat cycles, they can degrade over time. A cracked or broken igniter stops the ignition cycle entirely, leaving you without hot water or heat.
Part Dimensions and Physical Specs
Before choosing a replacement, check that the dimensions match the original component in your appliance to ensure proper clearance inside the burner assembly.
- Height: 0.8 in / 2.03 cm
- Length: 11.45 in / 29.08 cm
- Width: 11.35 in / 28.83 cm
Recognizing Failure and Handling the Part
A common sign of a failed igniter is a system that tries to start, clicks or hums, but never lights. You may also see a visible break or crack across the element upon visual inspection.
Always handle new and old igniters by their base or mounting hardware. The ignition material is fragile and can snap easily under light pressure. Keeping your fingers off the element ensures that body oils do not create hot spots that degrade the material faster.
Safe Removal and Installation Steps
Follow these steps when swapping out an old igniter with the same part number.
- Shut off electrical power to the appliance at the breaker panel and close the manual gas shutoff valve.
- Test the wires to confirm no electrical voltage is present before opening the burner access panel.
- Take a clear photo of the existing wiring setup and mounting location for reference.
- Disconnect the wiring connector carefully and remove the mounting screws holding the old bracket.
- Set the replacement part into position without touching the element. Move wires one at a time to the matching spots.
- Fasten the mounting screws securely, replace all access panels, and restore gas and electrical power.
Read your old part
- Locate the identification sticker or stamp on your old part or burner bracket.
- Verify that the number stamped on the old component matches 100271888 exactly.
- Check that the mounting bracket shape and screw hole pattern line up with your existing setup.
- Confirm the voltage requirement matches the original component, which is often 120 V.
- Ensure the listed physical dimensions fit the clearance space inside your equipment burner compartment.
When to call a pro
Working on gas equipment involves serious risks. Gas valve adjustments require testing gas pressure, which should only be done by a professional. If you are unsure of any step or suspect a gas leak, stop right away and hire a licensed HVAC technician.
Questions
Why should I avoid touching the igniter element?
Igniters are brittle and break easily. In addition, natural oils from your fingers can transfer to the element, creating hot spots that shorten its working life.
Can I swap igniters that run on different voltages?
No. Most hot surface igniters operate on 120 V, but some run on 80 V. These ratings are not interchangeable, so the voltage must always match the original part.
What should I do if I smell gas while checking the igniter?
Do not operate any light switches or electrical devices. Leave the building immediately and call your gas provider from outside.
What happens when an igniter cracks?
A cracked igniter breaks the electrical pathway, preventing the element from getting hot. The equipment will attempt to start, but the burner will never light.
Related part numbers
- 100110899Water Heater 100110899 Igniter, A.O. SmithSame brand and type
- 100191120Igniter, A.O. SmithSame brand and type
- 00-424194-00001Ignitor/Flame Sensor Assembly, Vulcan HartSame part type
- 100074673Flame Sensor, A.O. SmithSame brand
- 100217965Pressure Switch Reference, A.O. SmithSame brand
- 19A738Ignitor Rod Assembly, UltrafryerSame part type
- 100112456Igniter, A.O. SmithSame part type
- 1091257Fan Blade, ICPMore part numbers
Browse: A.O. Smith part numbers · Hot surface igniters by part number
All part numbers · Part number replacements · Shop igniters · Repair guides
Brand names and part numbers identify the part and show fit. HVAC Fitter is not affiliated with, authorized by, or endorsed by any equipment maker. If you are not sure a repair is safe for you, call a licensed HVAC technician.