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Why Your Gas Furnace Won’t Work When the Power Goes Out

Gas Furnace Power OutWhen 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 Furnace

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.

Power Outage Gas Furnace

Will Gas Heat Work in a Power Outage?

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.

After a Power Outage With Gas Furnace

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

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.

*Last Updated 06/11/2021


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