If your furnace keeps turning off and on, your thermostat may be the culprit. A malfunctioning or improperly placed thermostat can cause your furnace to short cycle. Common issues include: Old wiring or dead batteries: Replace batteries or old wiring to ensure accurate temperature readings.
You Have a Clogged Air Filter
One common explanation for a furnace starting and stopping repeatedly/furnace short cycling is that your air filter is clogged with dust and dirt. When this occurs, the airflow to the heat exchanger becomes restricted, and the component overheats.
First check to see if your vents or ductwork are clogged with dust and debris. This slows down the airflow into your home. With less air, your furnace needs to work harder and run longer in order to heat your home to its desired temperature. And this overwork can lead to your furnace turning on and off ad infinitum.
You may simply have a malfunctioning thermostat, for instance, that is registering temperatures wrong and needs to be replaced. A very dirty air filter in a forced air heater is actually a very common cause, too, with the increased airflow resistance leading to overheating and, in turn, causing the system to shut down.
A furnace cycling on and off repeatedly can be caused by various reasons, from dirty filters and obstructions in ducts and registers to incorrect thermostat settings and faulty limit switches. By following the steps above, you can help prevent your furnace from cycling too frequently and save energy costs.
There are several common reasons your boiler might be short cycling, which we've broken down below: Your boiler is more powerful than it needs to be. Boiler pressure is too high or too low. Your thermostat is faulty.
The simple solution: Turn your furnace off and check the filter. If it's dirty or it's been 3 months or more since you changed it, put a new, high-quality filter in place.
If your furnace keeps turning off, check for issues such as: Dirty Air Filters. A clogged filter restricts airflow, causing the furnace to overheat. Replace air filters every 60 to 90 days to prevent this problem.
When a furnace is short cycling, it's working hard to produce heat but isn't making any, causing strain on your furnace. If left unchecked, this could cause major issues for your furnace resulting in hefty repairs.
Turn your thermostat on and wait 15 minutes before comparing temperature readings. If the difference between what your thermostat says and what the thermometer says is more than a degree, your thermostat may need to be recalibrated.
Heat Exchanger Obstruction – When the coils inside the heat exchanger are blocked by dust or other debris, the restriction of airflow could cause the short cycling you're experiencing. Thermostat – If the thermostat has shorted out or is set to the wrong settings, you could experience some short cycling.
The most common problems are: Power outages - Power surges or outages remove power to the thermostat, causing it to restart or reboot. Sometimes, the outage can last just a second or two, and not be noticed. Dead batteries – Some older thermostats aren't hard-wired into the electrical system and run on batteries.
Other Possible Causes of Short Cycling
If you've ruled out a dirty air filter or a malfunctioning thermostat, the problem may be caused by one of the following: Corroded flame sensor. Improperly sized heating system. Foreign objects lodged in the chimney or air vents.
Some other reasons your HVAC system won't stay on due to short cycling are incorrect sizing, frozen coils, low refrigerant due to a leak, a faulty compressor, or malfunctioning control board. These issues require the help of a professional HVAC technician to fix through heating repair.
A furnace may short cycle when the heat exchanger is overheated, likely due to a lack of airflow. The heat exchanger is where the air gets heated. It will trip the furnace's safety switch when it gets too hot, which shuts down the operation to protect the system from dying.
Oversized furnace
This is the most common cause of furnace short cycling. If the furnace has been short-cycling since it was first installed, it may have been improperly sized for your home.
There are four common reasons why a furnace would short cycle; It has a dirty air filter inhibiting airflow to your blower motor, your thermostat is malfunctioning, you have poor insulation, or your furnace is oversized.
The typical heating cycle lasts 10-15 minutes. If your furnace shuts off after a few minutes and starts more than eight times an hour, it may require repair. Common causes of furnace short cycling include restricted airflow, a malfunctioning flame sensor, or a poorly placed thermostat.
Generally, a furnace cycle lasts anywhere between three to 10 times every hour; however, the frequency changes depending on several factors. If your furnace is cycling on and off more frequently than it should, there could be a problem with one of its internal components.
Dirt, dust, and debris may block the bearings, and when this happens, odd noises are common. Are bad bearings your issue? If the furnace starts clicking but still heats normally, rusty or corroded bearings are a likely problem. Lubricating sticking parts and replacing any worn-out bearings should stop the clicking.
Thermostat Troubles Can Cause Short Cycling
Your furnace or central air conditioner spends a good amount of energy simply turning on and off, which is why you want yours to run for at least 15 minutes at a time before shutting off.
In the heating, ventilation, and air conditioning (HVAC) business, short cycling is a phrase used to describe when a heater or air conditioner cycles on and off too frequently. It signifies a problem in your heating system's proper functioning and efficiency, in which it is not completing its heating processes.