Short-cycling is when your furnace turns off and on too often and is a common problem many Duncan, South Carolina, homeowners face. It drives up utility bills and puts a tremendous amount of strain on your furnace, so it’s important to determine why it’s happening. Many issues can cause short cycling, including an oversized furnace, a malfunctioning thermostat, and closed or blocked supply vents.

Oversized Furnace

An oversized furnace is a common cause of short cycling. If your furnace is too big for your home’s square footage, it’ll heat your home too quickly before turning off. Then, it’ll cycle back on shortly after shutting down. Without intervention, this pattern will continue all day and night, leading to wear and tear that will damage your furnace and possibly cause it to break down.


Overheating is another common cause of short cycling. When your furnace overheats, it turns itself off to prevent damage. Overheating is often caused by a relatively minor issue, such as a dirty air filter or blocked supply vent. However, a cracked heat exchanger, which is a serious issue that requires immediate attention,  can also result in overheating, so it’s important to determine the cause and resolve it as quickly as possible.

Malfunctioning Thermostat

When something goes wrong with your thermostat, your entire heating system can be affected. If you suspect your thermostat is causing your furnace to short cycle, replace the batteries. If that doesn’t help, you might consider replacing it. You can also have an HVAC company come out to check the wiring and your sensors.

Closed or Blocked Supply Vents

Check your supply and return vents to make sure they’re all open and air is flowing. Closing just one vent can cause a pressure imbalance in the ducts, which can result in numerous problems including short cycling. Dusting your vent covers a couple of times a year will also help, as will making sure no vents are blocked by furniture, boxes, etc.

If your furnace is short cycling, give George M. Hill & Sons, Inc a call today to make an appointment.

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