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It’s the end of the month, and you’re going through your bills. You’ve paid your rent or mortgage, the credit cards, and the water and internet bills. You come at last to the electric bill, only something looks different. This month, the energy bill is through the roof. It’s higher than it’s ever been, and you can’t begin to imagine why. You think back through the last month and can’t remember having the heat cranked up, or leaving the lights on all night. So what’s going on?

A few possible culprits could be causing an unusually high electric bill. Some of them are fairly harmless, but some of them the may indicate a severe problem lurking beneath the surface. If you happen to notice an anomaly such as this in your electric bill, don’t ignore it. The problem could be more serious than you think.

Why Is My Energy Bill So High?

To help you narrow down what might be causing your problem, here are some of the top reasons for an unusually high electric bill.

  1. Inefficient Appliances

    Are any of the appliances in your home a little past their prime? Before you say no, think carefully about the wide range of appliances in your house — the washer, dryer, dishwasher, refrigerator or more. If any of these appliances are getting up there in years, they could be at least partially responsible for the spike in your energy bill. This is because of two primary reasons.

    The first reason is that old machines simply have to work harder. As the parts get old and wear down, they don’t run as smoothly as they used to. Therefore, to do the same job, the machine must work extra hard consuming more energy than normally necessary.

    The second reason is that machines and appliances were not always designed with efficiency in mind like they are now. Nowadays, every appliance comes with an ENERGY STAR® rating that gives you crucial information about how much electricity the appliance will consume, and thus, engineers design with this in mind. However, this didn’t come about until fairly recently. This means that if you’re hanging on to any gadgets from the 1990s, they could easily be responsible for guzzling electricity in your home.

    The solution is simple — it’s time to upgrade your appliances. While there will be an upfront cost to making this upgrade, these appliances will pay for themselves over time in the form of lower electric bills.

    If replacing your appliances is not an option, you might also try cleaning and maintaining your appliances. Clean the individual parts and clear out any dust, dirt and debris that may have accumulated and been responsible for the machine struggling to do its job. Try replacing any broken parts for new ones, and put a fresh spin on your old appliance. This will likely not have the same dramatic effect as purchasing a new appliance, but it may still help.

  2. A Poorly Insulated House

    While light bulbs, refrigerators and TVs are responsible for a portion of your electric bill, they only represent a tiny fraction of your energy consumption. The vast majority of our electric bills goes towards heating our houses in the winter and cooling them in the summer.

    It can be challenging to maintain a controlled temperature in a large space like a house or apartment under the best of circumstances. But it becomes even harder when your home isn’t airtight. If the heated or cooled air is leaking out of your house and the air from outside is leaking in, then your climate control has to work twice as hard and is likely spending twice as much energy to achieve the same results.

    The easiest solution to this problem is to take measures to keep doors and windows closed as much as possible. Don’t leave the door open for longer than it takes to go in and out. If you’re feeling overheated in the winter, don’t crack a window. Turn down the heat inside instead.

    A more long-term solution is to investigate your insulation. If the walls of your home are poorly insulated, the heat or cold could be leeching out through the walls themselves. Fix this problem by giving your home an insulation-overhaul. The better insulated your home is, the easier it will be to control the temperature and the less money you’ll spend doing so.

  3. An Overworked Water Heater

    Your water heater is another appliance that is responsible for consuming a large portion of your total electricity usage. This will be the case no matter how efficient you work to be. However, based on the way you have things adjusted, it’s possible that you may be wasting more electricity than necessary in this single area.

    It’s recommended that most water heaters be set at 120 degrees Fahrenheit. Any lower, and your water may not be hot enough. Any higher and it will become a safety hazard as well as an enormous drain on your energy bill.

    The logic behind this is simple enough. If you have your heater set up to 140, which many people do, you’re not being efficient with your energy. You don’t need your heater set that high. It won’t do you any extra good, and all you’re doing is wasting additional energy in getting your water to this unnecessarily-high temperature.

    What will likely happen is that this heat will leak out through the heater, escaping into your basement or wherever else the heater is stored. This means your heater has to work harder to keep the heater at the specified temperature, all the while the heat is steadily leaking out into the outside air.

    Avoid this problem by targeting a lower temperature. Set your heater at 120 degrees and see the difference in energy savings.

  4. Fluctuating Energy Prices

    Unfortunately, no matter how many steps you take to make sure your home is operating efficiently and you aren’t consuming more energy than necessary, there is one significant factor that you can’t control — the price of your electricity. Ultimately, that’s up to the electric company, and there isn’t much you can do to change this. That’s the bad news. The good news? There are a few ways to work around this.

    First, it’s important to understand that energy rates fluctuate based in part on demand. During the peak of summer, when it’s extremely hot out, electricity might cost more just because there’s such high demand as everyone is looking to cool their homes. The same applies in the dead of winter when everyone is cranking up their heat. If you notice your energy bill is particularly high one month, it’s entirely possible that there has been such a fluctuation in the energy prices lately.

    So how do you deal with this? Your best and simplest bet is to be aware of these high-demand times and decrease your energy consumption during them. For example, it might not be the best idea to run multiple loads of laundry on the hottest or coldest days of the year.

    In addition to this, you can always try looking for different energy deals. Maybe a different provider will offer you a better deal, or perhaps you can switch to a different plan that will help you save a little extra on your energy bill.

  5. You’re Home More

    This one isn’t rocket science. We use more electricity when we’re actually home to use it. While certain appliances will run even when you aren’t home, such as the heat or A/C, refrigerator and water heater, the vast majority of energy-consuming machines in your house stay shut off when you’re not there. This includes light bulbs, electronics, TVs, washing machines, dryers, dishwashers and more.

    Most of us realize this, and that’s why we make efforts to shut the house down before we leave. We switch off light bulbs, for instance. Many of will even dial down the heating or cooling when we aren’t there. Both of these things help save electricity and save you money.

    It stands to reason, then, that if you’re home more often, it’s very likely that you’ll consume more energy. The lights will be on, the heating or cooling will be running at full blast, and the rest of your house will be active, too. Someone might be showering, someone else might be running loads of laundry or cooking dinner in the oven, and someone else might be watching TV. All of this energy wouldn’t be used if no one was home.

    Because of this, if you receive a high energy bill at the end of the month, it might be wise to think back over the past weeks. Have you or your family been home more than normal lately? Maybe you’ve been working from home, or the kids are on a break from school. Maybe it was a holiday, and nobody had to work. Any of these could be the culprit behind your high bill.

    While this is an explanation, unfortunately, it isn’t much of a solution. This increased energy consumption is a natural result of more people spending more time in your home. However, you can take comfort in knowing that this month was likely an anomaly and that next month, things will be back to normal. And if this does represent a new normal, perhaps if you’ve started to work from home or some other permanent change has come to your house, then there are plenty of energy-saving methods to look into that can help.

How to Lower Your Energy Bill

When faced with an unusually high bill, we recommend running through the items listed above and checking if any one of these things might be causing the uptick in energy usage.

However, just knowing the reason for your high energy bill isn’t enough. Once you know the cause, the next and arguably more important step is figuring out how to lower it again. Here are our top tips to help you do just this.

  1. Adjust Your Thermostat

    This one is an easy fix. Just take the thermostat and raise it a few degrees if it’s summertime and lower it a few degrees if it’s winter. There’s no need to go crazy on this step, either. You might be surprised about the difference a few degrees can make.

    One way to make this adjustment is to move your thermostat by just one degree at a time. When you reach the point where you find it’s too uncomfortable and unpleasant, just go back one degree. If you live with a family or roommates, be sure to be respectful and consult their opinion on this.

  2. Check Your Insulation

    Nothing helps lower your energy costs like a little extra insulation. By adding insulation to your walls, you’re keeping the heat or cold inside, while keeping the outside air out. This means your climate control has an easier time of managing your temperature, which saves you money on your energy bill.

  3. Unplug, Unplug, Unplug

    Did you know that most appliances and electronics consume energy even when they’re not in use? This includes TVs, laptop charger cables, toasters and so much more. While it might not be practical to crawl behind your dryer to unplug it every time you’re finished using it, there are plenty of areas where this can apply. It’s the work of a few seconds to unplug your phone charger when it’s not being used, for example.

  4. Minimize Your Usage

    We’re not advocating for you to stop using your washing machine or dishwasher — these appliances can be more efficient than doing such tasks manually, so there’s no reason to cut them out of your life. However, you can save both money and energy by only using them in full loads. Rather than running them often with half a load of laundry or dishes inside them, wait until you have a full load. You’ll find that by practicing this method, you run them less often and thus, use less energy.

  5. Schedule a Tune-Up

    Despite your best efforts, your energy bill might remain high. No matter how much you conserve, you may not be able to get that figure down. If you find that this is happening to you, it may be time to schedule a tune-up with your HVAC professionals. They’ll be able to check that your system is healthy and if they notice it needs maintenance or replacing, they will be able to do so. As a result, your energy bill should drop again.

Contact Oasis Heating, A/C & Refrigeration

A high energy bill is nothing to ignore. After all, this doesn’t happen for no reason, and it could be a warning sign of a larger issue in your house. By investigating this problem, you can save yourself from future months of high bills, as well as help your home to run a little more smoothly and efficiently.

For more information about your home’s heating and cooling systems, as well as what you can do to improve their performance, contact us at Oasis Heating, A/C & Refrigeration. We’re happy to answer your questions on the topic and help you get the energy-efficient home you deserve.

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When the weather outside is cold and windy, there’s nothing as enjoyable as a nice warm furnace inside your home. After all, it’s much more reliable than a baseboard heater or other form of electric heat, right? If you lose power in a storm, those electric types of heat will falter and leave you with a cold house. Your natural gas furnace would never do that, right?

Unfortunately, that’s not entirely true. If you’ve ever asked yourself if a gas furnace works during a power outage, the answer is that it is just as susceptible to power outages as electric heaters. While it might seem counterintuitive and confusing, your gas furnace still depends on electricity to power itself and heat your home. If the power is out, the odds are good your furnace will be out as well.

There are plenty of reasons why your furnace works the way it does and how you can interpret what’s going on in your current situation. There are also many options you can try if it seems like the power has returned, but your furnace hasn’t. If you’re experiencing a gas furnace with no power and wondering what to do when the power’s out, we’ve compiled this quick and easy guide just for you.

Modern vs. Traditional Gas Furnaces During Power Outages

Does a gas furnace use electricity? And, will a gas furnace work in a power outage? To answer these questions, it’s crucial to understand the difference between modern and traditional gas furnaces. In old-fashioned gas furnaces, there was something called a pilot light, or a pilot flame — a standing flame that burned at all times.

This little and constantly lit flame was responsible for igniting the natural gas and causing your furnace to work, allowing heat to flow through your home. If this flame were ever to go out, the furnace would turn off. In other words, there was no electricity involved. This explanation is an oversimplification, of course, but it serves our purpose for now.

Having one tiny flame controlling the entire furnace led to problems, such as the pilot light going out and turning the furnace off at inconvenient times. To fix these issues, innovators figured out how to do away with this older system, and modern gas furnaces rely on new methods of operation. Our current system is typically called electric ignition. As the name suggests, this system uses electricity to kickstart a flame and get the natural gas flowing. Therefore, if there’s no electricity, modern furnaces won’t start, as opposed to the traditional furnace that could likely continue without issue.

What a Power Outage Means for a Modern Gas Furnace

Does gas heat work when the power goes out? We’ve established that the answer to this question is most likely no. But what exactly is going on inside your furnace that causes this? How does a power outage affect gas heat? Let’s get some quick answers.

  1. The Gas Valve Shuts Off
    In most modern furnaces, it isn’t as simple as being unable to function without electricity. With some furnaces, it’s a failsafe mechanism, not a malfunction. Because it’s not safe to try to light many furnaces without electricity, the furnace will sense when there’s no power, and the gas valve will close, cutting off the flow of gas and preventing the furnace from functioning. This safety feature is something you should appreciate, not tamper with.
  2. The Heat Stops Working
    Because the gas valve has shut, the gas cannot flow and ignite, meaning the heat will stop working. There is an exception to this rule, however. If you have a generator, you will likely be able to use your gas furnace during a power outage. Without a generator, however, this is unlikely.
  3. You Will Not Have Hot Water
    Will a gas water heater work without electricity? The answer is no. If the heating systems in your house are connected, a gas furnace with no power will affect your water as well. The furnace will be without power, meaning your hot water heater won’t be working either. You’ll be limited to strictly cold water.
Why Doesn’t a Gas Furnace Work During a Power Outage?

There are several reasons for this, a few of which we’ve touched on. But the truth is that this is a question with multiple answers, so let’s look at all the reasons separately.

  • The Ignition System: This system essentially switches the furnace on and gets the gas flowing. Without electricity, this won’t be operational, and the gas won’t be able to turn on. You should never attempt to restart this manually, as doing so could result in serious accident or injury.
  • The Gas Valve: As we’ve mentioned, this valve is a safety feature installed in most modern-day furnaces, so even if the ignition system was to work and the gas was to ignite somehow, it couldn’t flow throughout the pipes. It’s vital because if gas were to escape into the system without electricity to guide and control it, any number of accidents could occur, resulting in damage to the furnace, as well as potentially to your building and to anyone in the vicinity.
  • The Blower Fan Motor: This part of the furnace guides the hot air and the gas, moving it through the pipes and preventing it from sitting still, building up under mounting pressure. If the fan isn’t working, the gas will either sit or rise naturally, and will potentially lead to a dangerous buildup in the pipes.
  • The Digital Thermostat: The thermostat is the part of the furnace you interact with the most every day, as someone who isn’t a technician or heating professional of any type. Without electricity, however, the thermostat will cease to function, meaning you have no control over the amount of gas in the furnace, and the temperature of the heat in your home. That is inherently dangerous, as it cuts off your ability to control the gas. For this reason, the gas valve shuts down when there is no power, to prevent this eventuality from becoming a reality.
How to Handle a Gas Furnace After a Power Outage

Even though gas heat doesn’t work when the power is out, this won’t usually be something you have to worry about. Most power outages are occasional blips that only last a few seconds or minutes. In cases like these, you’ll likely barely even notice your heat ever switched off.

However, there are rare events when the power is out for days or even weeks, perhaps as the result of an intense storm or a flood. In cases like these, as your home begins to grow cold and the furnace refuses to turn back on, what should you do?

  1. Don’t Experiment With the Furnace
    If you’ve ever had experience with furnaces, fixtures, electronics or heating equipment, you may think you have the know-how to tinker with your furnace and get it working again. We strongly discourage this.Remember, when there is no power, the gas valve shuts off for safety reasons, cutting off the flow of gas to prevent the furnace from working. Even if you were to get the gas flowing, you would have no way to control it. The entire process would be extremely hazardous and has the potential to result in disaster.No matter how much experience or technical know-how you may have, do not tamper with your furnace in an attempt to bypass these safety features.
  2. Cut off the Power
    The electricity is out, but that doesn’t mean there might not be odd spikes and surges of power if the power lines have become damaged somewhere. To prevent these power spikes from damaging your furnace — or any other sensitive electronics, for that matter — unplug the item in question. This way, even if the power does fluctuate, it will have no way to reach your furnace and damage it.
  3. Use a Generator
    If you have a generator, this is one of the only courses of action you can take during a power outage that has the potential to safely get your generator running again. You can hook it directly up to your furnace, powering it with electricity and getting it running.This process is not as simple as it may seem from the outside, however, and you should not attempt it blindly. Read the instructions carefully. If you don’t have an instruction manual, look up a tutorial or instructions online. Even then, complete the process with extreme caution.If mechanics and technology are not your strong suit, perhaps it might be best not to attempt this process at all. If these are the types of jobs you’re much more comfortable passing off to someone else, there’s no harm in doing so. Ask a friend or family member with strengths and a background in this area. Or, even better, you can always…
  4. Call a Professional
    Furnaces are often highly tricky and temperamental pieces of equipment that are usually best to leave in the capable hands of trained professionals. Rather than tinkering with your furnace and trying to connect a generator on your own, you are likely far better off calling a professional and letting them connect it for you.If you attempt to do this yourself, but are unsure of the correct way to do it, it’s possible something could go wrong and potentially damage the furnace or the generator. It’s always better to get something done right the first time around, to save you from having to do it twice. If that means calling a professional, there’s nothing wrong with that. They’ll be able to do it quickly and correctly, or, if it’s impossible, they’ll be able to tell you this as well.
What to Do After a Power Outage

So your power was out. Maybe it was for a few hours or a few days. Either way, it’s back on now, and your furnace should be working just fine. Except maybe it isn’t. What if your heat doesn’t automatically come back on? How do you restart a gas furnace after a power outage?

Before we even begin to troubleshoot, it’s worth noting this eventuality is unlikely. In most cases, your furnace should turn back on automatically as the power comes back online. Things should continue without a hitch. Think of it the same way you would think of a light bulb. If the power went out when a light was on, that light should automatically turn back on as soon the power gets restored, provided no one turned the switch off.

If this doesn’t happen, however, there’s no need to panic. Here are a few things you can try.

Furnace Checks After Power Outage:
  1. Make Sure the Furnace Is On
    We mentioned earlier that it might be a smart idea to cut off the flow of power to your furnace during an outage. If you did this, remember to check that this connection has been restored, allowing the now-working power to reach your furnace.
  2. Check the Control Panel
    In many cases, the control panel may be flashing with an error message, alerting you to the need for a replacement or repair. If this is the case, your furnace will not work, and you’ll need to call a repair professional.
  3. Check for Blown Fuses
    Was the power outage the result of a severe lightning strike? If so, it’s possible a fuse has blown. Again, it’s best to call in professionals to fix this type of problem.
  4. Check the Safety Lock
    When you attempted to restart your furnace, did you hit the reset buttons multiple times in quick succession? That has the potential to engage a child-safety lock. Essentially, the furnace designers built in a mechanism that assumes if someone is hitting the button many times, it may be a child, and the furnace will shut down as a safety precaution. Wait a while, then hit the reset button once firmly.
  5. Check the Thermostat
    Did your thermostat switch off during the power outage as well? Check to make sure it is back online, and turned up high enough to engage the furnace and start warming your home again. Set it at least five degrees hotter than the current room temperature and see if that makes a difference.
  6. Check Your Breaker Panel
    Occasionally, power outages can result in a tripped breaker. The good news is, this is a straightforward fix. Visit your breaker panel — usually in the garage, laundry room or other out-of-the-way space — locate the correct breaker, and flip it back on.
  7. Check the GFI Outlet
    If your furnace is relatively new, it may be connected to a GFI outlet. These are protected outlets, designed to trip if they get overloaded with power. This outlet may have become tripped during the power outage. If this is the case, all you need to do is reset it by pressing the reset button.

Contact Oasis Heating, A/C & Refrigeration Today

Are you struggling to get your furnace working after a power outage? Don’t tough it out alone. If you’re in the Northern Virginia area, contact Oasis today, and we’ll help you get your furnace up and running again. We’re a family-owned and -operated business with multiple generations of experience in the industry, so you can be sure you’ll receive the high-quality help and know-how to get your furnace running again in no time.

Fill out our contact form today or give us a call now.


  1. http://www.oasiscooling.com/contact/contact
  2. https://www.hunker.com/13415625/how-to-restart-a-gas-furnace-after-a-power-outage
  3. http://www.oasiscooling.com/blog/problems-with-your-electric-furnace-lets-look-into-it/
  4. http://www.oasiscooling.com/blog/why-most-modern-furnaces-use-electronic-ignition/
  5. https://extension2.missouri.edu/gh5117
  6. http://www.oasiscooling.com/blog/why-your-gas-furnace-wont-work-when-the-power-goes-out/
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When it’s cold outside, we want to stay comfortable inside. To ensure comfort during the winter months, nothing is as essential as 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 wrong furnace size for your home is an all-too-common mistake that can lead to uncomfortable temperatures and unnecessary expenses. To avoid these headaches, follow our detailed guide on how to accurately calculate the furnace size that is most suitable for your home.

The size of a furnace is based on how much heat it can produce in an hour, as measured in BTUs, or British thermal units. A BTU is the energy required to heat a pound of water by one degree Fahrenheit. The higher the BTU rating a furnace has, the more warmth it can provide.

What’s the Right Size Furnace for My Home?

If you’re building a house, you may be wondering how many BTUs you’ll need to heat it. The first factor you should consider is your home’s square footage. Bigger homes, generally speaking, require more BTUs to heat. Keep in mind, however, that this is just a starting point. Below are the BTUs required for homes of certain sizes.

  • 1,200-square-foot house: 36,000 to 72,000 BTUs
  • 1,500-square-foot house: 45,000 to 90,000 BTUs
  • 1,800-square-foot house: 54,000 to 108,000 BTUs
  • 2,100-square-foot house: 63,000 to 126,000 BTUs
  • 2,400-square-foot house: 72,000 to 144,000 BTUs

As you can see, the BTU usage recommended for each house size is not a single number but rather a broad range, so square footage alone is not particularly helpful. To get a more accurate idea of the BTUs it takes to heat your home, you’ll need to consider several other factors, which we will discuss later on in the article. First, we will explain why getting the right size furnace is so important.

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 you a slew of problems.

If Your Furnace Is Too Big

Some may assume an oversized furnace will ensure their home stays warm, but this is not the case. A furnace that is too big can lead to the following problems:

  • 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 house to warm up too quickly and become uncomfortably hot. That will, in turn, cause the heater to shut off, resulting in some parts of the house feeling like an oven and others like a freezer.
  • Less energy efficiency. Frequent turning on and shutting off makes oversized heaters inefficient.
  • Short lifespan. Constant cycling on and off of the heater will cause wear to the system and premature failure.
  • You will have to repair it often. Not only will your system have a shorter lifespan, you’ll likely have to repair it as well — and this can be expensive.
If Your Furnace Is Too Small

If your furnace is too small, you’ll also run into several problems, many of them the same:

  • You’ll feel uncomfortable. This is especially true on the coldest days of the year, when your furnace will be unable to keep up with the low temperatures. Undersized furnaces cannot make up the difference to make your home feel comfortable.
  • High energy bills. Because your furnace will be running nonstop, your monthly energy bills will be higher than they need to be.
  • Short lifespan. This constant running will also cause your furnace to wear out sooner.
  • Uneven heating. There will be cold or hot spots around the house.
The Right Size Furnace

A furnace that is the appropriate size for your home will warm up your house gradually. By doing this, it will be much more energy-efficient, and your equipment will last much longer. If you’ve noticed your furnace is running practically all the time, it may very well mean your furnace is too small. And if you notice it’s starting and stopping all the time, it could indicate your furnace is too big.

With an adequately sized furnace, you shouldn’t be dealing with any cold or hot pockets. It is important to remember, though, that on exceptionally cold nights, even the right size furnace may not be able to keep you comfortable. This is nothing to worry about — it just means you may still need to bundle up occasionally.

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.

  1. Calculate the square footage of your home.Add up the areas of all the rooms in your home you would like to heat. Your calculations will usually include all rooms, but it is possible the ducts in your home do not connect to the basement or the attic.Here’s a guide for calculating the area of rooms of specific shapes.
    • To measure the area of a rectangular room, multiply the length and width.
    • To measure the area of a triangular room, multiply the length and width, then divide the product by two.
    • For the area of a circular room, start by measuring the radius r, which is the distance from the edge of the room to the center. Then calculate πr2. If your calculator does not have a pi (π) function, use the number 3.14.
    • For unusually shaped rooms, divide them into smaller sections and measure each one separately.
  2. Find out What Climate Zone Your Home Is InClimate is another factor that helps determine how many BTUs you need to heat your home. Generally speaking, the farther from the equator you’re located, the more BTUs it will take to heat a square foot of your home. However, some geographic factors such as elevation and ocean currents cause BTU requirements to vary at any given latitude. Below are the five climate zones in the United States.
    • 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 west to Missouri and Kansas. It has a heating factor of 40 to 45 BTUs.
    • Zone 4: This zone includes Boston, New York and Chicago. Its heating factor is 45 to 50 BTUs.
    • Zone 5: This is the northernmost zone in the continental United 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 example, Chicago and New York are both in Zone 4, which has a heating factor of 45 to 50. If you live in either of these cities, you will need a heater that produces 45 to 50 BTUs per square foot. Los Angeles and Atlanta, on the other hand, are in Zone 2, which means you’ll need 35 to 40 BTUs per square foot.

    If you live in a new home or one with good insulation, you should use the lower of these two numbers. If your home is older or your insulation is poor, go with the higher number. If you’re not certain, it is always safer to go with the higher number, but try to come as close as you can so you don’t end up buying a furnace with more capacity than necessary.

    For example, let’s say you live in a well-insulated 1,900-square-foot home in Zone

  3. Multiply your square footage by 40, the lower number recommended for the climate zone. This calculation will give you 76,000 BTUs, which should comfortably keep your house warm in that climate.
Other Factors to Consider When Sizing a Furnace For Your Home

It is necessary to consider more than just square footage, climate and insulation, however. Here are some other things you should factor in.

  • Windows: If your home has a large number of windows, heat is more likely to escape. It may require you to choose a number near the upper end of your heating factor range, especially if they’re older windows.
  • Exposure to sun: The amount of sunlight that hits your home will also help determine how many BTUs you need. If you have rooms that are almost always shady, reduce the necessary capacity by 10 percent. If the house gets a lot of sun exposure, increase the capacity needed by 10 percent.
  • The number of dwellers: The human body dissipates heat into the surrounding air, so if a certain room regularly hosts several people, it will require fewer BTUs to heat.
  • Kitchen: For the kitchen, add 4,000 BTUs.
  • The number of floors: If you live in a two-story house, you will require slightly fewer BTUs because the second floor helps insulate the house.
  • Age: Newer homes tend to have better insulation and fewer areas for the heat to escape.
  • Desired temperature: Most people prefer temperatures between 70 and 80 degrees Fahrenheit, although if you prefer to keep the thermostat unusually high or low, this will affect your BTU requirement.
  • Ceiling height: If your ceilings are exceptionally high, your home will require more BTUs to heat comfortably.
  • Ceiling fans: Ceiling fans can improve circulation in your home, which can help lower BTU usage. They do this by distributing temperatures evenly throughout the entire house.
  • Ductwork: If your ductwork and furnace size don’t match up, it could cause problems. For instance, if your ductwork isn’t big enough for your furnace, this will shorten the furnace’s lifespan because the air the furnace produces won’t have enough space to travel through. That will restrict the flow of air and may cause the furnace to overheat. Make sure your furnace is appropriately sized for your ductwork.
  • Color of your roof: Darker-colored roofs absorb more energy from the sun than lighter ones. Even roofs that are dirty absorb significantly more energy than new, clean white roofs, which results in noticeably different BTU usages.
  • Shape of your house: A house that is long and narrow will require more BTUs to heat than a square house that has the same square footage. That is because a long, narrow house has more exterior walls and will experience more heat loss as a result.
Furnace Efficiency

When you go furnace shopping, you’ll notice two important numbers: a listed input rating, in BTUs, and an efficiency rating percentage. This second number indicates how effective the furnace can convert air to heat. You must look at both numbers to get a good idea of a furnace’s actual capacity.

Let’s go back to our hypothetical 1,900-square-foot house: If you find a furnace with 90,000 BTUs and an 80 percent efficiency rating, your output will be 72,000 BTUs. This furnace would be suitable for, say, an older home in Atlanta or Los Angeles, and would be more than sufficient for a new home with good insulation. If this 1,900-square-foot home is in Washington, D.C., however, and the furnace you’re looking at has an 80 percent efficiency, the input rating should be 100,000 BTUs.

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

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

Leave It to Our Expert Furnace Size Estimators

Even now that you understand all the factors that can affect your BTU requirements, sizing your furnace may still feel like a daunting task. If you’d like to be sure your furnace is the right size, leave 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 need.

If you live in Northern Virginia and need an installation, repair or maintenance for your heating, cooling or air quality systems, we are the professional team you can rely on to get the job done. We make sure to install the right equipment for your home, and do every job properly and to code. We believe every customer deserves valuable service, and we won’t sell you products you don’t need.

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


  1. https://www.hunker.com/12613355/how-big-of-a-furnace-do-i-need-for-a-1600-square-foot-house
  2. https://www.wikihow.com/Calculate-BTU-Per-Square-Foot
  3. https://www.inchcalculator.com/calculate-many-btus-needed-heat-home/
  4. https://www.calculator.net/btu-calculator.html
  5. https://santafeair.com/help-guides/buyers/what-furnace-size-should-i-get-for-an-1800-square-foot-house
  6. https://www.lennox.com/help/faqs/equipment-size
  7. https://www.fountainhillsair.com/articles/how-do-i-know-what-size-furnace-to-buy/
  8. http://www.lcsheatingandcooling.com/2017/10/signs-your-furnace-is-too-big-or-small-for-your-home/
  9. http://www.oasiscooling.com/
  10. http://www.oasiscooling.com/contact/contact
  11. http://www.oasiscooling.com/heating
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