What is the size of the round combustion air opening required for gas appliances totaling 350,000 BTU/h using the one opening method?

To determine the size of the round combustion air opening required for gas appliances totaling 350,000 BTU/h, the one opening method must be applied, following guidelines provided by the National Fuel Gas Code and local regulations.

The formula for calculating the required combustion air opening is based on the total BTU input of the appliances and the type of fuel being used. Generally, for gas appliances, the requirement is to provide 1 square inch of free area for every 1,000 BTU/h of input when using the one opening method.

In this case, for appliances totaling 350,000 BTU/h:

1. Calculate the total square inches of the opening: 350,000 BTU/h ÷ 1,000 = 350 square inches.

Next, to convert the square inches to a round opening size, you can use the formula for the area of a circle:

Area = π × (radius)^2.

To find the diameter of the required opening:

1. Rearranging the formula to solve for diameter: Diameter = 2 × sqrt(Area/π).

Substituting the Area you calculated (350 square inches) into this formula provides the required dimensions. Upon calculation, this leads to a diameter