Furnaces are rated on their btus of energy consumption not their btus of energy output.
60000 btu furnace square footage.
With a less efficient furnace operating at 80 percent efficiency this would require a.
A 60 000 btu furnace will adequately heat most mid size family homes in zone 1 and zone 2.
Btu charts furnace output and air conditioner size for a bungalow bungalow area sq ft furnace output btu hr air conditioner size ton built after year 1980 built before year 1980 built after year 1980 built before year 1980 up to readmore.
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.
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.
But before we buy an 80 000 btu furnace there s furnace efficiency to consider as well.
With these numbers you can calculate your furnace btu.
On the other hand the colder zone 5 climates of the northeast upper midwest and pacific northwest demand 50 60 btus per square foot for maximum efficiency.