Lochinvar & A.O. Smith 100108635 Orifice

The Lochinvar & A.O. Smith 100108635 is a precision-engineered natural gas orifice designed for high-efficiency commercial water heaters and boilers. This #33 drill size orifice is machined from durable 3/8" hex brass, ensuring consistent thermal resistance and reliable gas flow regulation under varying manifold pressures. As an essential component for stoichiometric combustion, this replacement gas orifice maintains the specific BTU input required for peak equipment performance. It is commonly utilized in various Lochinvar Knight and A.O. Smith Cyclone models to ensure the correct fuel-to-air ratio. When performing HVAC burner maintenance or a gas valve replacement, verifying the burner orifice size is critical for preventing incomplete combustion or soot buildup. This OEM burner part provides the exact tolerances needed for Lochinvar boiler repair and commercial water heater service, offering a seamless fit and direct compatibility with existing manifold assemblies in the field.

• Precision Machined: The 3/8" hex brass construction allows for secure torque application without stripping the threads during installation.
• Optimized Combustion: The #33 NAT orifice rating ensures precise gas metering to meet the manufacturer’s specified firing rate.
• OEM Compatibility: Replaces legacy part numbers including 100108635 and Lochinvar ORI2033 across multiple commercial platforms.
• Corrosion Resistance: High-grade brass material resists the corrosive effects of gas additives and moisture for long-term operational stability.

What is the specific drill size for the 100108635?
This component is a #33 drill size orifice specifically calibrated for natural gas applications in high-recovery heating systems.

Does this orifice work for Propane (LP) conversions?
No, this is a natural gas orifice. Converting to LP requires a different orifice size to account for the higher BTU density and lower manifold pressure requirements of propane.

Which models use this 3/8" hex orifice?
It is primarily utilized in A.O. Smith BTH 120-250 models and Lochinvar Knight (KB/WB) series boilers, though you should always verify the manifold pressure and BTU rating on the data plate.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.