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Proudly Serving the Conway Area

Proudly Serving the Conway Area


Dewees HVAC Blog

The Nonstop Furnace: Why It Runs for So Long


A common problem homeowners may face with their furnace is when the furnace keeps shutting off early, failing to complete a full heating cycle. 

But the opposite problem can occur as well: a furnace that runs for too long, seeming to never cycle down. This creates a huge energy waste, makes a house to hot, and puts so much strain on the furnace that it will wear down rapidly. If you’ve encountered a “runaway furnace,” you’re right to feel concerned. In most situations, a furnace that’s running for too long will need professional furnace repair in Maumelle, AR.

We’ll look closer into this problem and the reasons it occurs.

How long should a furnace run normally?

There’s no set time for a furnace’s heating cycle; it will vary depending on how cold the house is and how the thermostat is set. The average running time under standard winter conditions is around 15 minutes. In colder weather, the furnace may run through cycles more often, but it shouldn’t run much over 20 minutes. If it does—and your home is getting noticeably warmer than usual—you may need to call for professionals.

What can cause this longer running time?

We’ll list the most common culprits for a furnace that’s running too often:

  • Thermostat trouble: The thermostat controls when the furnace and blower fan turn on and off, so if the thermostat malfunctions, it can throw off the furnace’s normal cycling. This can be due to the thermostat sensing incorrect indoor temperatures, or losing its connection to the furnace.
  • Clogged furnace filter: This is a common source of the trouble, and thankfully one you can fix on your own. A clogged filter lowers the blower’s ability to draw sufficient air into the furnace to heat it, and this can lead to the furnace running for too long. Please change the filter every 1 to 3 months to prevent this from happening.
  • Heat exchanger problems: The heat exchanger is the metal part in the furnace that transfers heat from combustion gases to the air moving into the ventilation system. Heat exchanger problems can cause the furnace struggle to provide enough heat. Heat exchanger issues are potentially hazardous and need professional attention right away. 
  • Wrong sized furnace: If you have a relatively new furnace, the problem may be that whoever installed it did not properly size it for the house. An undersized furnace will have to run much longer to heat a house. The only repair for this problem is to replace the furnace with one that’s accurately sized. This is one reason to always go to experienced professionals for a new furnace installation. 

Call us for furnace help

If the furnace problem isn’t a simple case of a clogged filter or the wrong settings on the thermostat, we recommend you shut down the furnace and call our technicians. You don’t want to place any extra strain on the furnace, and you want to make sure there isn’t a safety concern. We’ll be out to solve the problem. We won’t do the job unless we do it right, no matter how hard it is!

Dewees HVAC proudly serves the Conway area—we’re here to keep you comfortable! Schedule help for your home’s furnace with our team. 

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