The calculation is simple. A basic rule of thumb for furnace size calculation is that it takes 30 BTUs for every square foot of house. So, if you have a 1,000 square foot house, you need a furnace that has a 30,000 BTU output.
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.
it is best to have the right size furnace as oversize will cause too many on-off cycles. too small causes extended periods of running and the possibility that it won't handle extreme cold.
Maintaining Temperature
The most common (and in many cases only) sign that your furnace is undersized is that the device simply doesn't maintain the temperature in your home properly.
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.
Neither oversizing nor undersizing your AC unit is ideal. Both scenarios can lead to issues with efficiency, comfort, and longevity of the system.
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 AFUE Rating on Your Furnace
There's a simple way to find out the energy efficiency of your home's furnace: Look at its AFUE rating. This number, found on the cabinet or in the user manual, is the Annual Fuel Utilization Efficiency measurement.
Insufficient return air can lead to higher energy bills. When your HVAC system doesn't receive enough return air, it must work harder to maintain the desired temperature, increasing energy consumption. Homeowners might notice a spike in utility costs without a corresponding increase in usage.
An oversized furnace can cause a number of problems, including increased energy costs, shortened furnace life, and uneven heating. If you're not sure what size furnace you need, talk to a heating and cooling professional.
No, you should not put a bigger blower motor in your furnace.
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.
The calculation is simple. A basic rule of thumb for furnace size calculation is that it takes 30 BTUs for every square foot of house. So, if you have a 1,000 square foot house, you need a furnace that has a 30,000 BTU output.
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. A 2,100-square-foot home will require between 65,000 to 125,000 BTUs.
Standard Efficiency : The most basic furnace being manufactured today, a standard or mid-efficiency furnace has an AFUE rating of around 80%. High Efficiency : If a furnace is considered a 'high-efficiency furnace,' it is rated as 90% AFUE or more.
Generally speaking, furnaces lose around 20 to 40 percent of their heating efficiency after many years of use. This occurs for multiple reasons, including dust buildup, vibrations, and damage to the heating element.
Efficiency and Furnace Cost
While high-efficiency furnaces with an AFUE of 96% or more cost between $2,000 and $6,000, standard-efficiency units with an AFUE of 80% to 89% are priced from $500 to $1,500. Upgrading to a high-efficiency furnace with a higher AFUE rating can lead to significant energy cost savings.
This is not a good thing and will lead to premature failure of the furnace. Besides premature failure, an oversized furnace will be prone to short-cycling, which is a term that refers to a furnace shutting down before the thermostat has been satisfied.
If you've been noticing that your furnace is running non-stop, there's a good chance it's too small for your home. And if it's constantly starting and stopping, you might be living with a unit that's too big.
First, know if you have a gas, electric or oil furnace. Electric furnace installation tends to be the least expensive, ranging between $3,000 and $7,000, according to HomeAdvisor. Installing a natural gas furnace falls in the range of $3,800 to $10,000, and an oil furnace ranges $6,750 to $10,0000.
To heat a 40×60 shop, which is 2400 square feet, you'll typically need between 108,000 and 132,000 BTUs.
When sizing your furnace, you need to count all the square footage of rooms you want to heat. If you want to heat your basement, count it when sizing your furnace.