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My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

The temperature you select for your furnace must be maintained during its operation. Your home will get chilly in the middle of winter if your furnace cycles on and off every few seconds. What specifically causes this problem, as you cannot possible repair it without understanding why it occurs?

A furnace that cycles on and off every few seconds is most likely short cycling, which could harm your appliance. There are various causes for brief cycling, some of which are as follows:

  1. Unclean air filter
  2. Thermostat issues
  3. Faulty insulation
  4. Effective furnace parts
  5. Unsuitable-sized furnace

Insufficient heat is produced by a short-cycling furnace, which frequently shuts off. Which approach will best address this problem? Learn more about the causes of short cycling, the causes of your furnace’s on/off cycling, and potential solutions by reading on.

How To Tell If Your Furnace Isn’t Cycling For Long Enough

If you’re still confused about whether your furnace is short cycling or if the chilly temperature is merely a product of winter, there are a few other indicators you may look for.

Short-cycling furnaces normally start up for four to seven seconds before turning off. However, the following additional symptoms should be taken into consideration in order to determine that short cycling is the problem:

  • Low room temperature: Your furnace may be short cycling if it has been on frequently and you have set the thermostat to provide you with adequate heat but the house still seems too cold.
  • Too many heating cycles: How long it takes for your furnace to reach the temperature you require will depend on where you are. For instance, if you don’t use a house during the winter, the furnace will run nonstop. On the other side, houses with efficient heating and insulation have quick heating cycles.
  • Difference between the temperature in the room and the setting set on the thermostat: This indicates that your unit is definitely short cycling, even if your home doesn’t feel that cold.

Short Cycles In A Furnace: Causes And Solutions

My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

You can move on to learning about its causes now that you are certain that your furnace’s problem is solely short cycling.

There are several causes of short cycling, and there is a remedy for each. The following is a summary of the reasons why a furnace short cycles, along with solutions:

1. Unclean Air Filter

My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

The airflow to the heat exchanger is hampered by a blocked air filter. The result is an overheated furnace. When your furnace notices this overheating, it knows the equipment needs to be turned off.

After a few seconds, it cools off and restarts. Depending on which of these your manufacturer advises, you should frequently clean or replace the air filter in your furnace to stop the short cycling.

Keep in mind that there are distinct instructions for cleaning or replacing filters for each furnace as you work to find a solution.

2. Issues With Thermostats

My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

Your furnace may short cycle as a result of the thermostat not functioning properly. Replace the thermostat’s batteries and turn it off to examine it. After some time, turn on your furnace. If the appliance stops short cycling after an hour of use, the issue will be fixed.

Check the position of your thermostat if batteries are not the problem. Your furnace’s heat cycle may be impacted by a thermostat placed close to a heat source.

Since thermostats regulate your furnace and are heat-sensitive, a nearby heat source will cause them to malfunction.
Verify that the temperature in the area is high enough to shorten the furnace’s cycle. To fix this problem, you will need to reposition your thermostat.

3. Lack Of Insulation

Your furnace will switch on early again if it has already heated your home, but the heat it produces leaks outside due to untreated windows. To stop warm air from escaping around your window frames, caulk the area.

4. Unreliable Furnace Parts

If none of the other options mentioned above apply, your furnace’s components may be the source of the short cycle.

Here are some malfunctions that may be the cause of this problem so you can determine if that is the case:

If the flue or flame sensor in your furnace blower is malfunctioning, your heat exchangers won’t warm the air or will get too hot, which will cause your furnace to shut off too frequently. Your vents won’t be able to circulate air if this occurs. If it does blow air, it will only be very little. To check if the vent is the source of the brief cycle, place your palm in front of it.

Another potential cause of your furnace’s problem could be blocked flues. Heated gases may not be able to escape if flues are blocked. In order to prevent overheating, this will cause the flue limit switch to turn the furnace off.

Your furnace may switch off if it senses that the ignitor isn’t producing a flame within four seconds due to a malfunctioning igniting flame. This lack of ignition could be brought on by a clogged or damaged thermocouple or damaged ignitor.

These malfunctioning furnace parts, in contrast to issues with the thermostat and air filter that result in short cycling, need to be fixed by a professional because they can be quite difficult to fix on your own.

5. Unsuitable Sized Furnace

Due to its system’s higher heating capacity than what you want, a furnace that is too large for your space will short cycle. It produces heat inside your home more quickly and shuts off right away.

Your furnace’s lifespan may be shortened as a result of this excessive use. Additionally, because your system consumes too much power, your electricity bill will increase.

To make sure your furnace suits your room, see a professional and replace it.

How Can A Furnace Be Prevented From Short Cycling?

Furnaces that short-cycle can be uncomfortable, especially if you need to keep your house warm in the winter. Follow these instructions if you don’t want to waste time attempting to research and repair your furnace:

  • Once a month, inspect and replace the air filter in your furnace.
  • Make sure the air vents in your home are open and unobstructed by furniture.
  • Have your machine tuned up annually by a professional.

By doing this, you will avoid the inconvenience of a cold house and save money on pricey furnace repairs.

How Much Does A Short-Cycling Furnace Cost To Repair?

Depending on what causes the short cycling, the average cost to repair a furnace ranges from $100 to $400.

Costs for furnace repairs can generally run between $125 and $480. The brand, size, state, and product warranty of your furnace will affect how much you might pay to fix it.

Final Thoughts

Short cycling is preferable to overheating as furnace issues because the latter doesn’t result in the appliance turning off. However, this does not imply that a short-cycling furnace should be disregarded.

By keeping an eye out for a few symptoms, you can confirm that short cycling is to blame for your furnace’s frequent on/off cycles. Short cycling is likely the root of the issue if your home feels chilly even while your furnace is running or if your furnace cycles through its heating cycle frequently.

A furnace may short cycle for a number of causes. While problems with the thermostat and air filter can be fixed to halt brief cycling, a professional repair is required if the device’s other components are broken.

However, replacing your furnace with one that is the right size for your room is your best option if an enormous furnace is the problem. A furnace that is the improper size will increase your power costs, which can cost you a lot of money.

My Furnace Turns On And Off Just About Every Second: Why And How To Fix It?

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Written by HVAC Contributor

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