Why Is My Furnace Heating Past Set Temperature?

Furnaces constantly work to serve you proper heat delivery when you want to heat your house. Until it reaches a certain thermal level the system will then have to revert to its default setup. However, sometimes it is not the case because it keeps running even if it's already past your preset temperature. We're here to help you figure out why this issue happens. Kindly read the answer below!

Generally, there could be several reasons why your furnace keeps heating even after reaching its preset temperature. Causes of a continually running furnace include:

  • the thermostat is set to "ON" mode
  • the thermostat battery is getting low on power
  • the thermostat is set incorrectly (too high or too low temperature for the area)
  • the furnace has a dirty air filter
  • leaking ductwork

That might seem straightforward. Well, keep on reading as we delve into how a bad thermostat affects your furnace working inefficiently. Also, we'll take a look at general furnace maintenance to keep the heat flowing with clean filters and sealed ducts. We will also teach you all the fixing procedures that you surely need in these situations. With that said, let's jump in!

photo of a man hand on the switch panel on the wall, Why Is My Furnace Heating Past Set Temperature?

Can A Bad Thermostat Affect The Furnace Operation?

The control system of your furnace unit would be the thermostat. You could decide when the heating or cooling system activates and what temperature your room will be at by setting the thermostat.

For instance, it doesn't cause any interference with your furnace system. No matter what your thermostat performs, the various parts of your furnace will continue to work as they should.

However, thermostat issues are just as problematic as having an issue with the furnace system itself because they interfere with your ability to regulate adequate heating throughout the house.

The furnace might also short cycle, or turn on and off quickly, as a result of a bad thermostat. The ideal cycle for a furnace to run before shutting its operation is at least 15 minutes.

photo of a man hand setting a switch panel attached on the wall

What Are The Causes Of The Furnace Running Constantly?

One of the most frequent complaints from furnace users is that their furnaces run continuously. Knowing what causes this problem is always a crucial thing to consider because the furnace is essential during colder times.

Typically, a furnace that runs constantly is due to damage or component that simply needs replacements.

Here are the lists of common causes we manage to dig in:

Dirty Air Filter

A dirty air filter can significantly affect the amount of air that your home's heating system can move. This implies that the hot air isn't reaching your living areas. You should replace the air filter as necessary once every 90 days.

You won't regret buying this Air Filter on Amazon.

Failing to do so, will lead to your furnace unit running constantly to meet your heating request.

Leaking Ductwork

Over time, fittings and seals in the ductwork in your home may become loose. Resulting in your furnace unit working much harder, longer, and more frequently to maintain your heating satisfaction.

Your best and most practical move to fix your inefficient ductwork is to inspect every potential leak and seal each area. It is said that a free from leaking ductwork system can increase its overall efficiency by as much as 20%.

Incorrect Thermostat Settings

The U.S. government advises to preset your thermostat to 68 degrees Fahrenheit in the winter. Doing so will allow and boost your comfort without sacrificing effectiveness.

Furthermore, the furnace will operate for a considerable amount of time if the thermostat is set to an incorrect setpoint. Just like setting it as high as the 70s or even into the 80s degrees Fahrenheit.

What To Do If Your Furnace Never Shuts Off?

Check your thermostat and ensure it is set in the "AUTO" mode, not "ON." Also, inspect the thermostat battery if it has enough power to supply the thermostat to properly assess the system's operation.

In addition, you also include inspecting your furnace air filter and changing it regularly. Setting your thermostat in a proper setup and replacing its battery regularly will help avoid this problem to show.

As per their average lifespan, thermostat battery replacement could occur every 8-12 months.

Check this thermostat battery on Amazon.

How Do I Replace My Furnace Air Filter?

Owning a furnace is indeed necessary in cold regions. It does involve some DIY upkeep that isn't usually enjoyable to follow, such as replacing a furnace filter. A lot of homeowners likely do not know how to handle a dirty furnace filter.

That's why when it needs replacement service, some of us resort to neglecting it rather than replacing it as recommended.

Throw your worries away! Here we purposely listed these easy simple replacing steps to guide you:

  1. Shut "OFF" your furnace unit's power supply.
  2. Remove the old dirty filter.
  3. Ensure that you buy the same air filter model and size that is compatible with your furnace unit.
  4. Securely reinsert your new filter and place it in line accordingly to where the arrow is pointing. A lot of furnace owners didn't pay much attention to where the arrow is facing so ensure to follow it.
  5. Now you can finally turn "ON" again the furnace unit's power source.

NOTE: These replacement steps may render irrelevant if you mistakenly install your furnace air filter.

Have a quick view of this visual tutorial on replacing your furnace filter on YouTube:

What Are The Signs Of A Bad Furnace Thermostat?

You should check the condition of your furnace system's thermostat as the winter season approaches to avoid freezing your house. The issue is that most individuals wait until it is too late to replace their thermostats.

Luckily, there are a few symptoms you can easily spot that indicate your furnace thermostat is going bad.

Here below are the checklist you can use to verify the signs of a bad thermostat:

Surges In Your Power Bills

You probably constantly hunt for methods to reduce your energy costs but an ineffective furnace can be the opposite outcome. If you discover that your energy bill is greater than usual then a bad thermostat is frequently to blame.

photo of an electrometer is measuring power consumption coins in foreground

Typically, an inaccurate thermostat reading will make your furnace unit work too hard. The unit's power consumption increases with the number of cycles it does each hour.

Thermostat Is Overly Old

Your thermostat will ultimately become obsolete, just like all other appliances in your home. The average home thermostat lasts 10 years. However, as years pass by your thermostat can become more susceptible to damage.

Thus, affecting the operation of your furnace unit's operational efficiency.

See this Dependable Thermostat on Amazon.

It Short-cycles Often

Short cycling is one of the primary reasons why you need to change your old thermostat. A problem arises when a cooling or heating cycle is not fully completed because the system shuts off earlier than necessary.

It's best to replace the thermostat if this problem continues to occur.

It Changes The Thermal Level On Its Own

Usually, a broken thermostat has trouble keeping its settings steady. It could abruptly and continuously change the temperature settings on its own. For a test run, try reducing the thermostat settings and observe the results.

The Furnace Unit Keeps Turning ON And OFF.

As we mentioned previously, a thermostat's main purpose is to communicate with your furnace unit. It instructs your furnace system to raise or lower the temperatures.

The thermostat likely has a problem if your furnace system has ceased responding to commands from the thermostat. This is due to your thermostat wiring being frequently susceptible to deterioration or fraying.

As a result, it compromises the contact with the furnace unit thus causing it to turn on or off more often.

How Long Should Furnace Run After Reaching Temperature?

A furnace can aid you more effectively control the humidity and thermal levels in your house. Even if you don't reside in a region with severely cold, harsh winters.

Even so, a cold house can be dangerous in addition to being uncomfortable. People who live in cold homes are more likely to get viruses, high blood pressure, and asthma. Generally, a furnace unit will cycle 3-8 times each hour.

Moreover, if it is working smoothly when set on auto mode, turning it off can cause you anything less stress. As long as your thermostat is not going bad or functioning well.

To Wrap Things Up

photo of a man hand on the switch panel on the wall

Your furnace unit is an integral part of achieving your home's desired temperature set point. It's critical to know why your furnace keeps on heating even though it's already past the preset thermal target.

Throughout this post, we address how a bad thermostat contributes to a negative impact on the way how your furnace operates. We've also talked about what causes this certain issue to show and how to avoid it.

You have also learned our detailed air filter replacement steps to prevent this from occurring again. We hope that reading all of this information will help you use your furnace unit effectively again.

Made it this far? Read our other useful article below!

Furnace Working But Not All Burners Lighting – What To Do?

Low Humming Noise In Furnace [Even When Off] – What To Do?

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