What Size Forced Air Furnace Do I Need

A heater s physical size has little to do with its heating abilities.

What size forced air furnace do i need. You need to purchase the right size furnace to heat your home effectively and manage your energy costs. For cooler climates a very broad estimate of furnace sizing is to select one that generates 40 to 45 btus per square foot. The size of a furnace is based on how much heat it can produce in an hour as measured in btus or british thermal units. The heater type such as radiant or forced air the british thermal unit btu output your garage s insulation and your available power all factor into your heater selection.

That means the furnace will produce 80 000 btu of heat. With a less efficient furnace operating at 80 percent efficiency this would require a. But the average homeowner can t simply go out and buy just any furnace. If you get the sizing wrong you will have a hard time escaping winter s chill and or your energy bill.

And if you re in need of a new furnace now is the time to act. The higher the btu rating a furnace has the more warmth it can provide. A mid sized home of 2 000 square feet would need approximately 50 000 to 60 000 btu to heat it properly. At 40 to 45 btus per square foot you d need a 100 000 to 112 500 btu.

Divide your btu output by 3 400 to find the kilowatt rating of the furnace that you need. What s the right size furnace for my home. You do this because 1kw can produce 3 400 btu of heat. Your local carrier dealer is experienced at calculating furnace size and will do what s called a load calculation to determine the size most appropriate for your home.

Different furnaces of the same input btu have different efficiencies measured in percentages. For example a furnace with an input btu can have an efficiency of 80. If the furnace you selected is more than 10 below your heating requirement we suggest you go up to the next size. If that same furnace has an efficiency of 95 the furnace will produce 95 000 btu of heat.

Most furnaces are offered in 15 000 20 000 btu increments so you just need to get close in terms of sizing. Typical residential gas furnaces will be available in various sizes between 44 000 btu h and up to 120 000 btu h. A btu is the energy required to heat a pound of water by one degree fahrenheit.