What Size Furnace Do I Need: Best Choice For Your Home

Home Tips

Winter is coming, but how to keep warm during the freezing days? If you are still concerned about the broken furnace, try to get rid of that thought and consider a new one with the desired size based on the guidelines in detail below.

Taking home a new household appliance is more of a trick than just spending money carelessly. Hence, hopefully, you can get a furnace suitable for your needs with the right size in the end.

What Size Furnace Do I Need: Best Choice For Your Home

How Are New Furnaces Measured?

According to their efficiency as expressed regarding AFUE that furnaces are measured. Another way to rate furnaces also based on their “size”, or heating output power, as expressed in BTU/h. When the question “What size a furnace do I need” comes up with your local expert, BTU/h is often referred. 

British thermal unit is BTU, and this term indicates the deal of heat needed to get one pound of water 1⁰ F raised. Furnace capacity is normally expressed in BTU/h, or sometimes the generation of British thermal units per hour is also regarded. 

To keep your home cozy, the correct size furnace for your house is indispensable when an undersized furnace is not strong enough to create enough heating power. It will run all the time to keep pace with the different needs. 

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Oversized furnaces will constantly turn on and off for the reason that it is providing more heat than usual, producing uncomfortable, fluctuating temperature swings and leading to inefficiency. 

Your local dealer is kinda good at furnace size calculation and most of the time will do a “load cal” to get the size most suitable for your house. A range of sizes between 44,000 BTU/h and up to 120,000 BTU/h will be ideal for residential gas furnaces typically.

Understand Furnace Efficiency Measurement

Once a load calculation conducted by your dealer to get the proper size furnace for your house has been completed, there are still final decisions for you to make. Understandably, two furnaces sharing heating capacity can lead to a range of efficiency measurements. 

Expressed regarding AFUE percentage, furnace efficiency measurement will be indicated with the yellow EG label standing for Energy Guide label on the furnace. AFUE means “annual fuel utilization efficiency” and it generally accounts for the proportion that is converted into heat for your house from one certain fuel source in terms of heating energy. 

If you wonder how it is calculated, you may not be too surprised as it works by considering the furnace’s total heating output over a year in connection with the deal of fuel used over a time that is related.

There are different requirements for distinguished heating fuel sources. However, the most typically used across the US, natural gas furnaces are needed to deliver 80% AFUE as a minimum level as such. 98.5% AFUE is known to be the highest level of efficiency models as known. 

Identification of the higher efficiency models can be effective as looking for the ENERGY STAR® logo as there comes a need for a new furnace too. ENERGY STAR® levels are kinda unrelated for each kind of fuel source. 

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What Size Furnace Do You Need?

Generally, it all depends, but you can choose the right size according to the recommended heating factors above. 

These are some specific examples:

  • You may need an 84,000 BTU-capacity furnace for your house if it is 2,500 square feet and you figure 35 BTUs per square foot.
  • Depending on the climate zone you are in, the furnace size for a house that is 3,000 square feet may range from 105,000 BTUs to 180,000 BTUs.

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6 Things To Remember Before Deciding Your Furnace Size

The performance of a load calculation to determine precisely the size of a furnace for your house may be done by a very professional contractor, probably following instructions from the ACCA standing for Air Conditioning Contractors of America. 

As pointed out, along with the average temperature outdoors in your area, the number of square feet in your house will be applied too. More features that should be examined include:

  • Attics, roof as well as walls in terms of home insulation
  • Wood-burning stoves or fireplaces related to extra heat-generating sources
  • The standard of ductwork is also a must to be considered
  • The number, the size, and of course the location of every window and door inside your house
  • Home orientation, and number of walls that are generally exposed
  • Open floor plan together with many spaces that are not surrounded

It can be seen that not all of the factors listed are the issue of getting out a tape measure as well as jotting down a couple of dimensions. 

You need to estimate what goes into a load calculation, and that is one reason accounting for relying on a professional contractor.

An illustration with a video seems to be better for you to understand the whole process:


1. How do furnaces work?

With 5 primary components inclusive of the thermostat, burners, the motor of the burner, heat exchange, and ducts; a furnace generally works efficiently. All of the aforementioned work in unison to simultaneously heat and distribute air to keep your house at the temperature desired. 

The thermostat plays a key role in measuring the temperature of the air and then tells your furnace when to turn on and off by using a gauge. Using buttons or a dial to adjust the temperature, a thermostat comes in two primary types including programmable and non-programmable thermostats. 

Scientifically speaking, during the day and night, programmable ones can change the temperature at a range of points automatically. In the meanwhile, to adjust the temperature, non-programmable thermostats must be manually changed. 

The heating process commences as the signal is sent from the thermostat and then got in the furnace, fuel then is also ignited. The temperature of the heat exchange system starts to increase as the burners are completely lit. Air over this heating system then will be circulated by a blower. The air is channeled into the ducts and your home will be warmer thanks to the furnace. 

2. Should you buy an electric furnace?

They are some of the most affordable to buy and are smaller regarding sizes, meaning they will be ideally appropriate for smaller homes. They work differently compared to other ones as they don’t use a burner but bank on an electrical ignition.

Electric furnaces gain popularity in such areas where there comes a shortage of natural gas lines, of course, these are inclusive of some rural communities.

3. What should you do if your furnace is suddenly out of work?

Other things still can go wrong even if the most common furnace issues hail from the thermostat. What should you consider if you are in such a circumstance? 

You should contact an expert for his assistance for sure. Nonetheless, make sure your breaker is off before you begin if you wanna take the DIY route.

What Size Furnace Do I Need: Best Choice For Your Home