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4 Reasons Your Furnace Keeps Turning Off and On

Woman adjusting the thermostat in a Hicksville, NY, home.

If your furnace keeps turning on and off, you may feel frustrated trying to understand what’s causing the problem. When a furnace turns on then off after a few minutes, this is known as “short cycling.” Unfortunately, there isn’t one straightforward solution to this problem since there are several reasons why your furnace may be short cycling.

As a homeowner, it’s not a stretch to say that you want your heating system to work properly. During the winter months, especially when temperatures are at an all-time low, it can be concerning when your furnace keeps going on and off. You want your family to feel safe and comfortable, and this issue can threaten to get in the way of this simple goal.

Below, we’ll discuss the four most common causes of a short-cycling furnace and how to get your heating system back to its usual performance.

1. An Old Air Filter

Dirty air filters can create several problems for furnaces. For instance, a dirty air filter can restrict the airflow to and from your furnace, which can lead to the heat exchanger retaining an excessive amount of heat. As a result, your furnace may end up overheating — and shutting down.

If your furnace turns on then off after a few minutes, inspect your air filter. Cleaning or replacing an old HVAC filter can help keep your furnace (and air conditioner) energy efficient. When these systems are working correctly, you can worry less about wear and tear and avoid costly repairs.

One way to ensure you don’t have a dirty filter is to schedule heating maintenance. During this service, HVAC technicians perform various duties to ensure your furnace is at the top of its game. These maintenance tasks often include inspecting, testing, and cleaning the unit — with a furnace filter replacement included.

When you stay on top of regular maintenance, you can prevent this short cycling problem we’ve all come to know and dislike. So, if your furnace turns on and off, your unit might just need a little extra care.

2. A Faulty Thermostat

If your furnace keeps turning on and off, it’s time to check your thermostat. Old wiring, dead batteries, or improper programming could be causing your furnace to short cycle.

Also, if your thermostat is too close to a heat source, such as a heat register, this could cause your thermostat to think that your home is warm enough and doesn’t need heat. As a result, your furnace may shut off and on because of the wrong temperature reading. This can be an incredibly frustrating issue to deal with, especially if your home never reaches your desired temperature.

3. An Oversized Furnace

It’s crucial to ensure that your furnace is the right size for your home. If it’s too big for your home (or too small), this can lead to problems — including short cycling.

When you have an oversized furnace, your home will be heated at an incredibly quick rate, and the furnace will shut off once it’s completed its job. This may be why it seems like your furnace turns on then off after a few minutes. The constant on-and-off cycle can cause considerable damage to your furnace, potentially leading to a premature replacement.

Common Signs of Oversized Furnaces

When your furnace turns on and off, it’s pretty difficult to ignore this problem while it’s happening. You can usually hear and feel this issue. However, there are a few signs that your furnace is too big for your home that are a little less obvious.

Additional signs of an oversized furnace can include higher-than-normal energy bills, hot and cold spots throughout the home, and the need for frequent repairs. If your furnace is the wrong size for your needs, it’s important to address this problem as soon as possible. This way, you can prevent your heating system from failing prematurely and avoid needing costly repairs.

4. A Dirty Flame Sensor

Your furnace has several safety devices, including a high limit switch and flame sensor. The high-limit switch keeps your furnace from getting too hot, while the flame sensor keeps track of how much gas is entering the furnace. If your furnace keeps turning on and off, a dirty flame sensor may be to blame.

When the flame sensor is dirty or corroded, it will be unable to do its job properly and might not sense a flame. If the flame sensor cannot sense a flame, it may be why your furnace turns on then off after a few minutes.

5. Closed Air Vents

If your furnace keeps going on and off and you’ve checked all of the potential reasons above, you’ll next want to inspect your home’s air vents or heat grates. You may have closed some of your vents in the past and forgot to re-open them. Also, it’s possible that a few foreign objects have become lodged in these vents.

Whatever the case may be, you’ll want to ensure that your air vents aren’t obstructed in any way. When these vents are blocked, you can limit the airflow to your furnace, which can lead to overheating and may be why your furnace turns on and off frequently.

It’s a good idea to keep your heat grates and vents open whenever possible. This way, you can prevent the parts in your heating system from breaking and needing repair. If you think your furnace has sustained damage due to overheating, don’t hesitate to contact our technicians for help. We offer everything from hydronic heating repairs to furnace services to restore your household’s comfort.

6. Blocked Exhaust Flue

Do you have a gas-powered heating system? If so, it’s possible that your furnace keeps going on and off because of a clogged exhaust flue. When your furnace’s heat exchanger creates combustion gases, these gases are safely removed via the exhaust flue. Unfortunately, this metal tube can become blocked with debris, such as animal nests or ice.

Since the exhaust flue is an integral part of your heating system, you’ll want to fix the problem as soon as you can. This way, your furnace will be able to work correctly. Although this issue could be why your furnace turns on and off at irregular intervals, it can pose a danger to your family. You don’t want the combustion gases to seep into your home.

Does Your Furnace Keep Shutting Off? Call Our Furnace Pros

If your furnace is constantly short cycling, one of these common causes may be to blame. However, if your furnace keeps turning on and off after several repair attempts by a professional technician, it may be time for a furnace replacement.

Every heating system-related problem is frustrating to deal with. Whether your furnace keeps going on and off or the unit makes strange banging or rattling noises, it’s important to work with an HVAC company that can provide you with a dependable solution. Fortunately, our professional team can help with your furnace repairs or replacement.

Do you need a furnace or boiler repair in NY? We’re committed to providing our customers with five-star service. From air conditioning system maintenance to heater repair in Hicksville, NY, the experts at Gold Star have done it all. We have the experience and dedication to meet all of your heating needs.
Get in touch with our friendly team to schedule a furnace replacement in Hicksville, NY, today!

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