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What Size/BTU Furnace Do I Need to Heat My Atlanta Home?

Posted 01-11-16 in Heating

Looking for a new furnace? Wondering what size (how many BTUs) you need to heat your home?

Here’s how to figure it out: Hire a reputable heating company to give you an estimate. Why do you need a professional? Because they should be performing a Manual J load calculation for you to determine the proper size.

Why a Manual J load calculation is necessary

Without a Manual J calculation, contractors rely on rules of thumb that can cost you serious money. They either use the size of your current furnace or the square footage of your home to determine the size your new furnace should be.

But these rules of thumb almost always result in a furnace that is too big for your home. 

And bigger isn’t better. A furnace that’s too big for your home will cost you in:

  • Higher energy bills. It will run for only a short time and then shut off. Then quickly turn back on. This is called short cycling and increases your energy bills (imagine shutting of your car every time you came to a stop light!)
  • Uncomfortable home. The short run times won’t distribute the heated air evenly, leaving hot and cold spots throughout your house.
  • Shorter lifespan. The short cycling wears down the furnace more quickly, shortening its lifespan.
  • Purchase price. Bigger systems cost more. 

Enter the Manual J load calculation…

What goes into a Manual J load calculation?

Manual J was developed by the Air Conditioning Contractors of America (ACCA). Manual J load calculations determine how much heating and cooling a house actually needs. They require that the furnace installer consider the home’s:

  • Insulation levels
  • Overall size
  • Height of ceilings
  • Orientation of home (north-south, east-west, etc.)
  • Size, location and type of windows
  • Size, location and orientation of rooms
  • Number of people in the home
  • Type of roof
  • And much more

All of these items contribute to how much heat your home needs during the winter, which determines the size of your furnace.

Check out this video for even more information on Manual J heat load calculations.

Get a free estimate from Coolray

Live in the Atlanta area? Want to know what size furnace you need? Contact us and we’ll perform a Manual J load calculation and give you a free estimate.

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