What is Short Cycling? What Causes a Short Cycle and How To Fix It?

Short cycling is an HVAC term used to define a situation where a furnace or air conditioner turns on and off too frequently. The term “short-cycle” describes the period of time that your HVAC equipment is actually running, and the shorter this cycle, the harder your system needs to work.

Since we at Minnick’s love to educate homeowners on their HVAC equipment, we hope that by the end of this article you will understand what causes short cycling, why it can be harmful to your HVAC equipment, and what you can do about it.

What Causes Short Cycling?

If you notice your home’s HVAC system is turning on and off more frequently than normal, your home may be having a short-cycling issue. Before you can correct your short cycling issue, you’ll need to first figure out where the root cause of the problem is. In our 60+ years of helping Maryland homeowners, here are some of the most common causes for short cycling that we find in residential homes:

  • Incorrect Unit Size. If you have a furnace or air conditioner that is too large for your home’s ductwork, it will cause a short cycle. An oversized furnace or air conditioner will use a lot of energy to heat or cool your home, which can cause the distribution of conditioned air in your home to be uneven. Uneven air distribution can lead to the room(s) housing your thermostat to warm up or cool down quicker than the rest of your house. This will cause your furnace/AC to turn on and off frequently in order to compensate.
  • Needed Maintenance and/or Repair. Homeowners who fail to regularly maintain their HVAC equipment are more likely to experience short-cycling issues. For example, a dirty air filter can restrict airflow, which may lead to short cycles. Other common examples that can lead to short cycles are condensated switch issues, a corroded flame sensor, or objects stuck in your vents.
  • Poor Thermostat Placement. If you’ve recently installed a new thermostat, it’s important to be aware of its placement within your home. For example, thermostats that are in direct sunlight, near heat-generating appliances, or vents may misread your home’s actual temperature and signal for your HVAC system to turn on and off prematurely. 

​Now that you understand what short cycling is and what can cause it, let’s examine the impact it can have on your HVAC equipment, home, and wallet…

Is Short Cycling Bad For Your Furnace and AC?

If your home’s HVAC equipment is short cycling, the constant cycle of on-and-off will put a strain on your equipment’s electrical and lubrication systems which reduce the overall life of your furnace or AC. The constant shutting on and off will also contribute to higher energy consumption and a spike in your utility bill. In fact, below are the three most common consequences for not fixing a short cycling furnace or AC unit.

  • Damaged Equipment. Constantly turning on and off puts stress on the parts in your furnace or air conditioner, causing them to wear out faster. 
  • Higher Energy Bills. Larger motors, like your furnace fan motor, use more energy starting up and shutting down than they do when they’re running. So a furnace that’s constantly turning on and off works much harder to heat your home and will require more energy, which raises your monthly utility bill.
  • Uneven Room Temperatures. If your furnace is turning on and off all the time, it won’t run as long, which means you’ll have uneven temperatures throughout your home.

​Now that you know how harmful and expensive short cycling is, let’s talk about what you can do to fix it…

Furnace Ignition

How to Fix Short Cycling?

The simplest and easiest thing you can do to prevent short-cycling is to regularly maintain your HVAC system with frequent inspections and cleanings. During this process, a trained technician can spot potential problems and correct them before they can lead to short-cycling problems. Short cycling, if ignored, will slowly degrade the health of your HVAC system and cost you more money in the long run.

Is your home’s furnace or AC short cycling? Since 1954, Minnick’s has helped thousands of Maryland homeowners restore their home comfort. Contact us online or call us at (301) 327-3038  and let us help you get to the root cause, so you can forget about your heating and cooling problems for good.

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Minnick’s is an industry leader in providing Heating, Cooling, Plumbing, Insulation, Indoor Air Quality, and Whole Home Energy solutions to Montgomery County, Howard County, Prince George’s County, Anne Arundel County, Baltimore County, and Baltimore City