Why Is My Thermostat Short-Cycling or Turning Off?
Thermostat short-cycling is one of the most annoying HVAC problems for homeowners. It keeps climate-controlled air from properly mixing, leading to warm and cool spots throughout your house. Short-cycling can also wear out HVAC components faster. How do you identify and deal with HVAC short cycling, though?
What Is Short Cycling?
A normal HVAC heating or cooling cycle tends to run about ten minutes on and then ten minutes off. HVAC technicians consider a cycle short if it runs for less than ten minutes and restarts sooner. In many cases, systems can cycle as frequently as three or more times in a ten-minute span if there’s a thermostat issue or an HVAC problem.
Common Reasons Your Thermostat Is Short Cycling
Placement
A thermostat’s placement may cause it to receive more cooled or heated air than it should. Keeping a thermostat near a register that blows on it, for example, may cause the sensors to indicate that heating or cooling has hit the target. Likewise, proximity to a refrigerator, stove, or south-facing wall can also convince the thermostat that it has completed a cycle. Blocked or missing return vents can cause climate-controlled air to accumulate near a thermostat, leading to short cycles.
Restricted Airflow
Clogged air filters are particularly notorious for triggering short cycles. If air backs up inside the HVAC unit, a safety shutoff may trigger. In some instances, the solution is as simple as replacing the filter with a clean one.
Blocked vents can trigger short cycles, too. Likewise, dirt evaporator coils on air conditioners and heat pumps may create icing that forces early cycle shutoffs.
Thermostat Wiring Issues
Loose connections between the thermostat and the HVAC also cause short cycles. A signal interruption leads to an immediate cessation of operation. Corroded HVAC wiring can cause a similar issue. Likewise, a dead battery in the thermostat will lead to cycling problems.
Mechanical Problems
The HVAC itself might have mechanicals issues.
Common trouble sources include:
- Leaking refrigerant
- Failing fans or blower motors
- Stuck dampers
- Damaged coils
Improperly Sized HVAC
An HVAC unit with too great a capacity for your home can lead to short-cycles. Strictly speaking, this isn’t an operational problem. Your house just cools faster. However, it does cause the HVAC to perform less efficiently, costing you money.
Thermostat Malfunction
A thermostat might malfunction for a variety of reasons. Dirt or debris in the housing could prevent air from getting to the sensors. Faulty sensors can also trigger short cycles. A thermostat that isn’t compatible with the HVAC may still communicate with it, but the results could be unpredictable. Age is another factor. Generally, you should consider a thermostat replacement if your home’s current one is older than ten years and causing problems.
How to Prevent Short Cycling
Scheduling an annual tune-up is easily the best solution. Our technicians can visit your home before summer starts to inspect the HVAC and verify that the thermostat is working properly. Oftentimes, the solution to short-cycling is just recalibrating the thermostat during a tune-up.
You should also:
- Keep vents and return registers open to ensure airflow
- Replace HVAC filters on a regular schedule of at least every three months
- Move furniture and curtains away from vents and air returns
- Choose a central location for your thermostat installation
Upgrading your home’s thermostat is also a good idea. We can match your thermostat to the HVAC model in your house. This ensures that the two systems will be compatible.
Especially if you’re moving into a house you recently bought, a new thermostat installation is a good idea. You can choose the features you want, such as scheduling, smart capabilities, geofencing, and connectivity. Also, you will have the peace of mind that comes with knowing that the thermostat is brand new. A programmable thermostat usually offers better accuracy, too.
Pro Tips from Lakeland One Hour AC & Heating
Monitor Cycles
More than anything, paying attention to your system’s rhythms is the best way to catch short-cycling before it costs you money. Even if the solution is as simple as replacing the thermostat, you don’t want a malfunctioning cycle to have time to wear down HVAC components. Track your system’s cycles during moderate weather. If you’re seeing cycles significantly shorter than ten minutes, talk with us.
The Two-Degree Rule
To prevent systems from short cycling, HVAC manufacturers build a two-degree buffer into the cycle. In other words, the AC doesn’t kick on for a thermostat setting of 72°F until the temperature hits 74°F. Likewise, the heater won’t kick on for a 72°F setting until the temperature hits 70°F. If your HVAC is short-cycling within these limits, there is likely a problem in the system rather than the thermostat.
Get a Smart Thermostat
Some models of smart thermostats track system runtimes and can alert you to undesirable cycling patterns. This gives you an earlier warning, improving the odds that you can schedule a fix before the cycling problem harms your HVAC.
A smart thermostat installation is highly cost-effective, with most models paying for themselves within 18 months through improved efficiency. If you have an older smart thermostat, your home may benefit from the additional features that some with a smart thermostat replacement.
Enjoy Consistent Year-Round Comfort
Lakeland One Hour AC & Heating is the trusted local name for HVAC work. We handle issues with air conditioning and heating units, including heat pumps and ductless mini-splits. Our technicians have the training and resources needed to quickly deal with installations, repairs, maintenance, upgrades, and replacements. You can also relax knowing that we’re on time or you don’t pay a dime.
If you believe the thermostat in your Lakeland, FL, home is short-cycling your HVAC, contact Lakeland One Hour AC & Heating right away.