Gas Furnace Btu Per Square Foot

One therm is equal to 100 000 btu or 0 10 mmbtu while 100 cubic feet of natural gas equals 103 700 btu or 1 037 therms.

Gas furnace btu per square foot.

Furnaces are rated on their btus of energy consumption not their btus of energy output. At 40 to 45 btus per square foot you d need a 100 000 to 112 500 btu. A more efficient furnace will output more btus of heat than a less efficient furnace with the same btu rating. For example if a furnace is rated at 100 000 btus and is 80 efficient then the heat output will be 80 000 btus 100 000 x 8.

What is a btu. Another quick and easy way to estimate the number of btu s required is with this helpful chart. For cooler climates a very broad estimate of furnace sizing is to select one that generates 40 to 45 btus per square foot. For example if you re trying to heat or cool 1 000 square feet you would multiply 1 000 by 20 and get 20 000 btus per hour.

2 000 square feet x 40 btus 80 000 btu output required thanks to the equation we know we need 80 000 btus of heat. 1 btu 1 055 joules 252 calories 0 293 watt hour or the energy released by burning one match. 1 watt is approximately 3 412 btu per hour. The british thermal unit or btu is an energy unit.

To learn how to adjust btu per square foot for special conditions scroll down. Once you have the total square footage just multiply that number by 20 to find how many btus per hour you d need to heat or cool the space. For example if you re trying to heat 1000 square feet in a cold climate 30 000 40 000 btu s will add significant warm air to your home. 1900 square feet x 40 heating factor from the chart above 76 000 btu required to heat your home.

Average square and cubic footage. But before we buy an 80 000 btu furnace there s furnace efficiency to consider as well. For example in zone 3 to 4 which typically requires 40 45 btu per square feet you can determine that a 2 500 square foot home would need a 100 000 to 112 000 btu furnace. It is approximately the energy needed to heat one pound of water by 1 degree fahrenheit.

Instead natural gas may be priced as dollars per therm. Then to calculate the output on a given gas furnace multiply it s efficiency rating by it s listed input rating to determine the actual btu output of heat. Another variable in determining your energy needs is space both in terms of square footage and cubic footage.