Sizing Calculator. The following technique can provide you with an approximate size estimate for your new furnace or central air conditioner. Although you may reasonably use this estimate as a first pass when browsing through furnace or air conditioner models, you (or your HVAC contractor) should complete a thorough load calculation before you make your purchase.
If the furnace you selected is more than 10% below your heating requirement, we suggest you go up to the next size. A little under sizing or over sizing is fine, just don't over size by more than about 20% of your heating requirement, or short cycling can occur which wastes energy and reduces your comfort
How Do You Size a Furnace for a House? There are several factors to consider when sizing a furnace for a house, including the square footage of the building and the climate it occupies. 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.
Knowing the number of BTUs required per square foot of space is important in choosing the right size furnace and air conditioning system to heat and cool your house efficiently and effectively. You'll have to determine the amount of space to be heated or cooled and choose the right furnace or air conditioner unit for the job.
A lot of real science is included in the methods of calculation when selecting the right size central air conditioner for your home. For instance, one of these methods is a Residential Load Calculation. Another method for sizing air conditioners is determining the size of the air conditioner system that's currently in place.
The size of the home is the first, obvious factor in determining the furnace size, but there are many other considerations also. Whether a home is open - with a few large rooms - or closed, with ...
You can use very basic calculations to get a rough estimate of the size of residential gas furnaces. ... you need a 40,000 BTU per hour furnace. If your house measures between 2,035 and 2,070 ...
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%. That means the furnace will produce 80,000 BTU of heat. If that same furnace has an efficiency of 95%, the furnace will produce 95,000 BTU of heat.
Furnaces are rated on their BTUs of energy consumption, not their BTUs of energy output. A more efficient furnace will output more BTUs of heat than a less efficient furnace with the same BTU rating. 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).
How to Calculate the Right Size Furnace. As you know, estimating the size of your furnace heating system involves considering a variety of factors. Here are the first two steps you should take to estimate furnace size. Calculate the square footage of your home.Add up the areas of all the rooms in your home you would like to heat.