What Size Furnace Do I Need For A 1500 Square Foot Home?

What Size Furnace

When information technology's cold outside, nosotros want to stay comfortable inside. To ensure comfort during the winter months, nothing is every bit essential equally a furnace — the great workhorse of domestic heating in the United States. For the furnace to work properly, however, it must be the right size. Buying the incorrect furnace size for your home is an all-also-common mistake that can lead to uncomfortable temperatures and unnecessary expenses. To avoid these headaches, follow our detailed guide on how to accurately summate the furnace size that is most suitable for your home.

The size of a furnace is based on how much heat information technology can produce in an hour, as measured in BTUs, or British thermal units. A BTU is the energy required to oestrus a pound of water by 1 caste Fahrenheit. The college the BTU rating a furnace has, the more than warmth it tin provide.

What'southward the Right Size Furnace for My Habitation?

Right Size Furnace Home Size

If you're edifice a house, yous may exist wondering how many BTUs you lot'll demand to heat information technology. The first cistron yous should consider is your home's square footage. Bigger homes, generally speaking, require more than BTUs to rut. Keep in heed, however, that this is merely a starting betoken. Below are the furnace BTUs required for homes of certain sizes.

Furnace for 1,200-square-foot house: 36,000 to 72,000 BTUs
Furnace for 1,500-square-foot house: 45,000 to ninety,000 BTUs
Furnace for 1,800-square-foot business firm: 54,000 to 108,000 BTUs
Furnace for ii,100-foursquare-human foot firm: 63,000 to 126,000 BTUs
Furnace for 2,400-square-foot business firm: 72,000 to 144,000 BTUs

Equally you can run across, the BTU usage recommended for each firm size is not a single number but rather a broad range, and then square footage alone is not particularly helpful. To become a more accurate idea of the BTUs it takes to estrus your dwelling house, yous'll demand to consider several other factors, which we will talk over after on in the article. First, we will explain why getting the correct size furnace is then important.

Why Does Furnace Size Matter For A Home?

Why Does Furnace Size Matter

Buying the right size furnace for your home will ensure you're comfortable and don't spend more on heating than you need to. Oversized and undersized heaters, on the other hand, will both cause y'all a slew of problems.

If Your Furnace Is Also Big For Your Home

Some may assume an oversized furnace will ensure their habitation stays warm, but this is non the case. A furnace that is too large can lead to the following bug:

You'll feel uncomfortable. Oversized heaters tend to work in quick bursts and, when it gets cold, they'll turn on and cause certain areas of the firm to warm upward too quickly and get uncomfortably hot. That will, in plow, cause the heater to shut off, resulting in some parts of the house feeling similar an oven and others like a freezer.
Less energy efficiency. Frequent turning on and shutting off makes oversized heaters inefficient.
Brusk lifespan. Abiding cycling on and off of the heater will cause habiliment to the system and premature failure.
Y ou will have to repair it ofttimes. Non just will your system accept a shorter lifespan, you'll likely accept to repair it as well — and this can be expensive.

If Your Furnace Is Too Small For Your Home

If your furnace is too minor for your home, you'll also run across several problems, many of them the same:

Y'all'll feel uncomfortable. This is specially true on the coldest days of the year, when your furnace will be unable to go along upwards with the low temperatures. Undersized furnaces cannot make up the deviation to brand your home feel comfortable.
High energy bills. Considering your furnace will be running nonstop, your monthly energy bills volition exist higher than they need to exist.
Short lifespan. This constant running will besides cause your furnace to article of clothing out sooner.
Uneven heating. There will be common cold or hot spots around the house.

The Right Size Furnace For Your Home

A furnace that is the advisable size for your home will warm up your house gradually. Past doing this, it will be much more energy-efficient, and your equipment will terminal much longer. If y'all've noticed your furnace is running practically all the fourth dimension, information technology may very well mean your furnace is too small. And if yous notice information technology's starting and stopping all the fourth dimension, it could indicate your furnace is as well big.

With an adequately sized furnace, you shouldn't be dealing with any common cold or hot pockets. It is important to recollect, though, that on uncommonly cold nights, even the right size furnace may non be able to keep you comfortable. This is nil to worry nigh — it only ways y'all may still need to packet up occasionally.

How to Calculate the Right Size Furnace

As you know, estimating the size of your residential furnace heating system involves considering a variety of factors. Here are the offset two steps y'all should accept to estimate furnace size.

Calculate the square footage of your dwelling. Add up the areas of all the rooms in your dwelling house y'all would like to heat. Your calculations volition usually include all rooms, but it is possible the ducts in your habitation do non connect to the basement or the attic. Hither's a guide for calculating the area of rooms of specific shapes.
- To measure out the surface area of a rectangular room, multiply the length and width.
- To measure the area of a triangular room, multiply the length and width, and then split the product past two.
- For the expanse of a round room, start by measuring the radius r, which is the distance from the border of the room to the heart. And so calculate πr². If your calculator does not take a pi (π) function, utilise the number 3.fourteen.
- For unusually shaped rooms, divide them into smaller sections and measure each one separately.
Find out What Climate Zone Your Domicile Is In Climate is another factor that helps make up one's mind how many BTUs you need to heat your dwelling. Generally speaking, the further from the equator yous're located, the more BTUs it will take to heat a foursquare foot of your dwelling. Even so, some geographic factors such every bit meridian and ocean currents cause BTU requirements to vary at any given breadth. Below are the five climate zones in the U.s.a..
- Zone 1: This zone occupies the most southern regions of the United States and includes Miami, New Orleans and Houston. It has a heating factor of 30 to 35 BTUs.
- Zone 2: This zone includes coastal California and the Southern cities of Atlanta and Little Rock. Its heating factor ranges from 35 to 40 BTUs.
- Zone 3: This zone includes Virginia and extends due west to Missouri and Kansas. It has a heating gene of twoscore to 45 BTUs.
- Zone iv: This zone includes Boston, New York and Chicago. Its heating cistron is 45 to 50 BTUs.
- Zone 5: This is the northernmost zone in the continental The states, including the cities of Buffalo and Minneapolis. Its heating factor is 50 to 60 BTUs.
Each climate zone has a recommended heating factor, which is the suggested number of BTUs per square foot. For instance, Chicago and New York are both in Zone 4, which has a heating cistron of 45 to fifty. If you live in either of these cities, you lot will demand a heater that produces 45 to 50 BTUs per foursquare foot. Los Angeles and Atlanta, on the other paw, are in Zone two, which means you'll need 35 to 40 BTUs per square pes.

If y'all live in a new habitation or one with good insulation, you lot should apply the lower of these two numbers. If your dwelling is older or your insulation is poor, become with the higher number. If you're not certain, it is always safer to become with the higher number, just try to come every bit shut as you lot tin can so you don't finish upwardly ownership a furnace with more capacity than necessary.

For example, allow's say you live in a well-insulated i,900-square-pes home in Zone
Multiply your square footage by twoscore, the lower number recommended for the climate zone. This adding will give you 76,000 BTUs, which should comfortably proceed your house warm in that climate.

Other Factors to Consider When Sizing a Furnace For Your Home

Other Furnace Sizing Considerations

It is necessary to consider more than than merely square footage, climate and insulation, still. Hither are another things you should gene in.

Windows: If your home has a big number of windows, heat is more probable to escape. It may require you to cull a number near the upper end of your heating factor range, especially if they're older windows.
Exposure to sun: The corporeality of sunlight that hits your home volition also help decide how many BTUs y'all need. If yous take rooms that are nigh ever shady, reduce the necessary capacity by 10 percentage. If the firm gets a lot of dominicus exposure, increase the capacity needed by 10 percent.
The number of dwellers: The human body dissipates heat into the surrounding air, and then if a sure room regularly hosts several people, it will require fewer BTUs to heat.
Kitchen: For the kitchen, add iv,000 BTUs.
The number of floors: If yous live in a two-story house, you will require slightly fewer BTUs because the second flooring helps insulate the firm.
Age: Newer homes tend to accept amend insulation and fewer areas for the heat to escape.
Desired temperature: Near people prefer temperatures between 70 and 80 degrees Fahrenheit, although if yous adopt to keep the thermostat unusually high or low, this will affect your BTU requirement.
Ceiling tiptop: If your ceilings are exceptionally high, your home will require more BTUs to oestrus comfortably.
Ceiling fans: Ceiling fans can ameliorate circulation in your home, which tin help lower BTU usage. They do this past distributing temperatures evenly throughout the entire house.
Ductwork: If your ductwork and furnace size don't match upwardly, it could cause problems. For case, if your ductwork isn't big enough for your furnace, this volition shorten the furnace'southward lifespan because the air the furnace produces won't have enough infinite to travel through. That volition restrict the flow of air and may cause the furnace to overheat. Make sure your furnace is accordingly sized for your ductwork.
Color of your roof: Darker-colored roofs absorb more free energy from the dominicus than lighter ones. Fifty-fifty roofs that are dirty absorb significantly more than energy than new, make clean white roofs, which results in noticeably different BTU usages.
Shape of your house: A house that is long and narrow volition require more BTUs to rut than a foursquare firm that has the aforementioned square footage. That is because a long, narrow firm has more exterior walls and volition experience more heat loss as a effect.

Furnace Efficiency In Your Home

When you lot go furnace shopping, you'll notice 2 of import numbers: a listed input rating, in BTUs, and an efficiency rating percentage. This second number indicates how constructive the furnace can catechumen air to oestrus. You must look at both numbers to become a skillful thought of a furnace's bodily chapters.

Let'due south go back to our hypothetical 1,900-foursquare-pes house: If yous find a furnace with 90,000 BTUs and an lxxx percentage efficiency rating, your output volition be 72,000 BTUs. This furnace would exist suitable for, say, an older dwelling house in Atlanta or Los Angeles, and would exist more than than sufficient for a new domicile with good insulation. If this one,900-square-foot home is in Washington, D.C., however, and the furnace you're looking at has an fourscore pct efficiency, the input rating should be 100,000 BTUs.

Furnaces typically have effectually an 80 percent efficiency rating, although more expensive, high-energy models have at least a 93 percent efficiency rating. The near mutual types are gas furnaces, which are required to have at to the lowest degree a 78 percent efficiency rating, with the nigh expensive models approaching 97 percent. Some electric furnaces are 100 percent efficient.

Note that the efficiency of your furnace will subtract with time and usage.

Leave It to Our Expert Furnace Size Estimators

Oasis HVAC Experts

Even at present that yous understand all the factors that tin can affect your BTU requirements, sizing your furnace may even so feel similar a daunting task. If you'd like to be sure your furnace is the right size, go out this job to the professional HVAC experts at Oasis. We have the expertise and equipment to provide a detailed analysis of your home, which takes into account your insulation, duct sizes, ceiling heights, window sizes and other constraints that affect the size of furnace you demand.

If you live in Northern Virginia and need an installation, repair or maintenance for your heating, cooling or air quality systems, nosotros are the professional person team you can rely on to become the job done. We make certain to install the right equipment for your dwelling house, and do every job properly and to lawmaking. We believe every customer deserves valuable service, and we won't sell y'all products you don't need.

Telephone call us at 703-997-8222 or fill up out our online form to schedule an appointment or learn more about our installation, repair and maintenance services. We look forward to hearing from y'all!

*Last Updated 06/01/2021

"Great timely service. Knowledgable and neat techs. Good value."

"Would absolutely use their services once more. Arrived on schedule."

-Springfield, VA

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