If a gas appliance has a 500,000 Btu/hour input with a double-wall metal flue, what is the required flue pipe size?

To determine the required flue pipe size for a gas appliance with a 500,000 BTU/hour input, it is essential to refer to relevant building codes and industry standards that govern vent sizing. For gas appliances, the size of the flue pipe is crucial to ensure proper venting of exhaust gases, prevent backdrafting, and maintain appliance efficiency.

A gas appliance with an input of 500,000 BTUs typically requires a larger flue pipe due to the volume of gas being expelled. When considering a double-wall metal flue, which is often used for higher BTU appliances because of its ability to handle higher temperatures and provide better insulation, the specific size must be calculated based on the manufacturer's specifications or standard venting charts.

In this case, the correct choice is an 8-inch flue pipe. This size accommodates the high volume of gases produced by a 500,000 BTU appliance, ensuring that exhaust is efficiently expelled without causing any safety hazards associated with inadequate venting. It aligns with the standard practices that recommend an 8-inch pipe for appliances with similar input rates, balancing sufficient flow and minimizing the risk of condensation within the venting system.

This choice reflects a thorough understanding of installation codes, safety considerations, and