What is the maximum altitude mentioned for appliance operation without changing gas input ratings?

For the operation of gas appliances without needing to adjust the gas input ratings, the maximum altitude established is 2,000 feet. This is a crucial detail in the installation and operation of fuel gas systems because as altitude increases, the density of air decreases, affecting combustion. If gas appliances are installed at elevations higher than this limit, the air-to-gas ratio changes, potentially requiring adjustments to maintain optimal performance. Therefore, adherence to this altitude threshold is important to ensure that appliances function efficiently and safely without necessitating alterations to their gas input configurations.

While the other options suggest higher altitudes, they exceed the recognized limit for standard appliances, which can lead to unsafe operating conditions if not properly adjusted. This is why the correct answer is 2,000 feet, aligning with industry standards for appliance operation at varying elevations.