Most charts follow guidelines similar to these: A 1,200-square-foot home will require between 35,000 and 75,000 BTUs. A 1,500-square-foot home will require between 45,000 to 90,000 BTUs. A 1,800-square-foot home will require between 55,000 to 110,000 BTUs.
How many square feet will an 80000 BTU furnace heat? A furnace with 80,000 BTU capacity can effectively warm up a typical home measuring 2,000 square feet.
A general rule of thumb is that you'll need about 30 to 60 BTUs per square foot of your home, depending on your climate zone. For example, if you have a 2,000-square-foot home, you might need a furnace rated between 60,000 and 120,000 BTUs. BTUs, or British Thermal Units, measure a furnace's heating capacity.
Even a slightly undersized furnace will accomplish the job the majority of the time. Taking things down a few sizes will more than likely solve some of your common heating problems like too high of a utility bill while half of your house is blazing and the other half is an icebox.
Your home will be uncomfortable. When your furnace is too big, it will blast your home with too much conditioned air at one time. This can make your rooms feel too warm when your furnace is operating and lead to major temperature swings in your home.
2,500 square-foot homes will typically need a furnace rated anywhere between 70,000 and 140,000 BTUS or higher, depending on your climate and the qualities of your home.
Many of the furnace size charts follow similar guidelines such as: 1,200-square-foot home will require between 35,000 and 75,000 BTUs. 1,800-square-foot home will require between 45,000 to 90,000 BTUs. 2,100-square-foot home will require between 65,000 to 125,000 BTUs.
While natural gas models have become the most common type of furnace used in the United States, oil furnaces are still available and commonly found in the Northeast. An oil system heats your home in much the same way as a natural gas model.
A 1,500-square-foot home will require between 45,000 to 90,000 BTUs. A 1,800-square-foot home will require between 55,000 to 110,000 BTUs. A 2,100-square-foot home will require between 65,000 to 125,000 BTUs. A 2,400-square-foot home will require between 75,000 to 145,000 BTUs.
To heat a 40×60 shop, which is 2400 square feet, you'll typically need between 108,000 and 132,000 BTUs.
Efficiency. The Annual Fuel Utilization Efficiency rating indicates a furnace's efficiency. Even though oil produces more heat per BTU, gas is generally considered more efficient. Oil furnaces offer AFUE ratings between 80% and 90% while gas furnaces offer ratings between 89% and 98%.
Home Size Determines Furnace Size
It's recommended that a furnace has 30 to 60 BTUs per square foot. The actual number depends on the climate which we will get into in the next section. But, just for example, if you have a 1500-square-foot home and live in a warm climate, you will multiply 1500 by 30.
A furnace that is too small for the house in which it is installed will put out too little heat to keep the home warm. So, the furnace will stay on for far longer than it is designed to do in an attempt to heat the home properly. This puts just as much stress on the system as if it were oversized, with the same result.
The more BTUs a furnace has, the larger the area it can heat. However, bigger isn't always better. If your furnace has insufficient BTUs, it'll work non-stop and never keep your home at a comfortable temperature. Alternatively, a furnace with too many BTUs will frequently cycle and be inefficient.
The Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI) suggests a rule of thumb of 30 to 45 BTUs per square foot for high-efficiency furnaces in colder climates. Accordingly, a high-efficiency furnace for a 3,000 square foot home would typically range between 90,000 and 135,000 BTUs.
How can owners prevent puff-backs? First, ensure your furnace maintenance is up to date; forgoing the annual cleaning and adjustment process increases the chance of combustion problems. Second, be alert for strange odors, noises, leaks, debris or soot around the unit.
Neither oversizing nor undersizing your AC unit is ideal. Both scenarios can lead to issues with efficiency, comfort, and longevity of the system.
No, you should not put a bigger blower motor in your furnace.