Combustion air is required at a rate of 50 cubic feet per how many BTU of input?

Combustion air is required at a rate of 50 cubic feet per how many BTU of input?

• A. 100 BTU
• B. 1,000 BTU
• C. 10,000 BTU
• D. 100,000 BTU

Answer: (B)

Combustion air must be supplied in a fixed ratio to the appliance’s input to ensure complete combustion. The standard rule is 50 cubic feet of air for every 1,000 BTU of input. This ratio provides enough oxygen for typical gas-fired appliances and safe venting in indoor spaces. So the correct match is the rate that pairs 50 ft3 with 1,000 BTU of input. The other numbers would imply too little air (for very small input) or far more air than is typically required for standard installations.

Combustion air must be supplied in a fixed ratio to the appliance’s input to ensure complete combustion. The standard rule is 50 cubic feet of air for every 1,000 BTU of input. This ratio provides enough oxygen for typical gas-fired appliances and safe venting in indoor spaces. So the correct match is the rate that pairs 50 ft3 with 1,000 BTU of input. The other numbers would imply too little air (for very small input) or far more air than is typically required for standard installations.