What Size Furnace Does My Home Need? If you don’t know the square footage of your home, it’s fairly easy to calculate it. To measure the square footage for your home, multiply the length and width of each room that you wish to heat. Add the measurements for each room together and you will come up with the square footage of your house.
A "working" estimate is figured out by knowing your climate, the square footage of the home, the size of the furnace and its efficiency. A standard that is used by heating and cooling equipment ...
A rule of thumb is to allow 25 to 30 BTU per square foot for moderate climates and up to 45 BTU per square foot in harsher climates. For a 2,000 square foot home, the ideal furnace size therefore varies from 60,000 to 90,000 BTU. Efficiency is an important consideration in selecting the correct size of furnace for a home.
For this example, using an 80% efficient furnace, the 1900 square foot home above would require a 90,000 Btu input furnace that produces 72,000 Btu's of heating, which is close enough to the 76,000 Btu's required using the climate heating factor.
Best Answer: I am a heating contractor in minnesota (very cold) and would only put a 40,000 btu furnace in that size home if it was newer construction with around 8' ceilings and decent windows. If you have a basement under the 1000 sq. ft. then you would want around 60,000 btu. Furnaces do come that small so don't listen to others who say they don't.
What Size Furnace Do I Need for a 1200 Square Foot House? Most 1,200-square-foot homes needs a furnace with an effective output of 40,000 to 50,000 BTUs. The effective BTU output, which is based on its efficiency rating, is a percentage of the BTU input rating. ... and the number and size of rooms are used to determine the exact size of furnace ...
My house is under 1000 sq ft, good windows, decent insulation. My furnace on low is about 33,000 BTU output and does fine at -5° out. Only use high for quick warmups and like evankoehnsays, sounds like wind howling through the vents. Should have gone 40K input but the supplier giving me a great deal doesn't sell that kind of furnace that small.
To calculate BTU per square foot, start by measuring the square footage of each room you want to heat or cool. Then, add the square footage for each room together. 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.
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
Furnace sizes are categorized by the number of BTUs the unit is capable of generating. For example, if your home is 1000 square feet and is in zone three, multiply 1000 by 40 What Size Furnace Do I Need for My Home by Square Feet ? Gas furnaces manufactured before the early '90s were 60 to 80 percent efficient.