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The Goodman B4089343 Burner Orifice (#43 drill size) is a genuine OEM natural-gas spud for the GMTH045-3B furnace and related Goodman/Amana models. The orifice threads into the manifold and precisely meters the volume of gas delivered to each in-shot burner. The #43 drill size is matched to the furnace's BTU input and gas type — using the correct orifice is essential for proper flame size, complete combustion, and safe operation.
Orifice sizing is not interchangeable — the drilled bore determines gas input and must match your furnace's rating and altitude. The OEM B4089343 guarantees the exact #43 bore Goodman specifies for this model. An incorrect orifice can under- or over-fire the furnace, causing sooting, short cycling, or a safety hazard.
Easy (2/5). Shut off the gas and power, remove the burner, and unthread the orifice from the manifold with the correct socket — do not over-torque or damage the tip. Confirm the drill number matches before installing. After service, check for gas leaks and verify a proper flame. High-altitude installs may require a different orifice size.