A. O. Smith 16" Final Burner Assembly for Natural Gas Water Heaters — #37 Orifice, OEM Replacement

The A. O. Smith 100112342 final burner assembly is a factory-compatible 16" natural gas burner designed with a #37 orifice to replace the original heating element in compatible water heaters.

This OEM replacement part restores safe, efficient combustion for A. O. Smith gas-fired units that require a 16-inch final burner with a #37 natural gas orifice. Built to the manufacturer's specifications, the assembly includes mounting points and the correct orifice sizing so installers can swap the old burner without modifying the gas train. Use this replacement when troubleshooting poor ignition, uneven flame distribution, or when the original burner assembly is damaged or corroded.

What does this burner assembly do for my water heater?

The final burner assembly directs and shapes the natural gas flame under the combustion chamber, ensuring proper heat transfer to the tank or heat exchanger. It replaces worn, warped, or corroded burners to help restore consistent flame pattern and combustion stability.

• Directs natural gas through a #37 orifice sized for correct flow rate
• Provides a 16" burner length to match original equipment geometry
• Restores correct flame distribution across the combustion zone

How easy is it to install the 100112342 replacement burner?

Installation is straightforward for anyone familiar with gas appliance work and basic hand tools, but always follow local codes and shut off gas and power before starting. The assembly bolts into the original mounting points and uses the same orifice size so no gas-line resizing is typically required.

• Remove access panels, shut off gas and power, and ventilate the area
• Unbolt the old burner assembly and detach any ignition or sensor connections
• Fit the new 16" assembly, tighten mounting hardware, reconnect sensors, and leak-test joints

Why is the #37 orifice important and what does 'natural' mean here?

The #37 orifice controls the gas volume delivered to the burner, tuning flame size and heat output to the heater’s design. "Natural" denotes natural gas (methane) as the fuel type—do not use this orifice with liquid propane without conversion parts and re-rating.

• #37 orifice matched to factory flow specs for correct combustion
• Naturally sized for natural gas; conversion to LP requires a different orifice
• Maintains manufacturer performance and safety tolerances when installed correctly

How can I tell if this specific part matches my heater?

Check your water heater’s parts list, owner manual, or the old burner label for the A. O. Smith part number 100112342 or a description showing a 16" final burner with #37 orifice. Cross-reference model numbers or consult a qualified technician if unsure.

• Verify OEM part number 100112342 or original equipment documentation
• Confirm burner length is 16" and orifice stamped or marked as #37
• Contact A. O. Smith support or a licensed service pro for compatibility help

Who is this for: This replacement burner assembly is intended for service technicians, HVAC professionals, and competent DIYers maintaining A. O. Smith natural-gas water heaters that require a 16" final burner with a #37 orifice. It’s not a universal part—use it when the equipment documentation or a parts diagram specifies A. O. Smith part number 100112342. Always follow safety practices, local regulations, and test for proper combustion after installation.