Combustion Air Calculator – CE Southeast Technical Support

Combustion Air Calculator 80% & 90%

Are you working on a 80% or 90%+ furnace?

80%

90%+

Please enter the TOTAL number of BTU’s of all the appliances installed in the space.

Please, include the total BTU input of water heaters, clothes dryers, etc.

You need this much cubic feet of space to support your appliances.

Now enter the size of the room where the appliances are installed.

Room Width

Room Length

Room Height

The space has this much cubic feet of air

Your space can support this many BTU’s.

You need to add enough air to support this many more BTU’s.

Congratulations!!! You have enough combustion air.

Congratulations!!! You have enough combustion air. You can use 1 vent pipe.

You do not have enough combustion air. You need to install 2 vent pipes, 1 for fresh air and 1 for the exhaust vent.

You will need to add air to the room. You could use transfer grills into another space to get air from another room or get fresh air from outside of the structure. If you install transfer grills into another room, you will need 2 sets of grills, 1 set installed high on the wall and 1 set installed low on the wall.

Your grills need to have this many FREE square inches of space.

sq in.

This is not the entire surface area of the grill but the actual free space opening of the grill please check with the manufacture product data to find the grill Free space area.

The room these grills need to connect to, needs to be at least this many cubic feet.

cu ft.

The room needs to be least this many square feet with the existing ceiling height you input.

sq ft.