What causes a furnace to keep cycling?
Another common cause of a short cycling furnace is that the furnace itself is overheating and it’s turning itself off to prevent damage. This causes the hot air in the furnace to become trapped. Restricted airflow is often the result of interior vents being blocked, a blocked exhaust vent, or a dirty air filter.
Why does my furnace cycle on and off frequently?
So, if your furnace keeps turning off and on too quickly, your thermostat might be malfunctioning or broken. If your thermostat is placed close to a heat source such as direct sunlight or a heat register, it will skew the temperature reading causing the thermostat to turn on and off irregularly.
How often should a furnace cycle on and off?
On average, furnaces should kick on and turn off anywhere from three to eight times per hour. However, if your furnace turns on and off more frequently, don’t assume the furnace is short cycling just yet.
What is considered short cycling for a furnace?
A furnace “short cycles” when it turns off before reaching the desired temperature. This means that if your thermostat is set to 72 degrees, the furnace may shut down at 65 or 68 degrees, but will never reach 72 degrees.
Why does my furnace shut off before reaching temperature?
A lack of airflow can cause your furnace to stop heating before reaching the set temperature. Ensure there is nothing impeding airflow around your furnace, within your furnace and through your ducts. Inside your furnace should be clean and free of debris, especially around the blower motor and the heat exchanger.
Why does my furnace cycle in the winter?
Check the thermostat – if the thermostat is not set at the correct temperature, that may be a cause of short cycling. In general, summertime temperatures should be set at 78 degrees Fahrenheit, and winter temperatures at 70 for maximum efficiency. If it is a digital thermostat, try replacing the batteries
What happens when you stop the ignition cycle on a furnace?
If the sensor does not detect the shaft spinning properly, then it will stop the ignition cycle. The next step does not have a sensor to check. The computer will just send a signal to the ignition source, whether it be a hot surface igniter, an intermittent pilot, or an electronic spark system.
Why does my furnace reset itself after it cools?
If the switch gets over a design temperature it will open and signal to the computer the furnace has exceeded the designed high temperature limit. This switch does reset itself after it cools because it can be triggered by dirty filters or other issues that are not a gas safety issue.
Why does my furnace keep running at a high temperature?
Another issue that could cause your furnace to heat constantly is a house that isn’t weatherized properly, allowing cold air to enter the home as hot air escapes. If your furnace continues to heat constantly but can’t reach your set temperature, have a professional inspect your system and home and provide possible solutions.
Check the thermostat – if the thermostat is not set at the correct temperature, that may be a cause of short cycling. In general, summertime temperatures should be set at 78 degrees Fahrenheit, and winter temperatures at 70 for maximum efficiency. If it is a digital thermostat, try replacing the batteries
How often should you run your furnace cycle?
If your furnace is operating correctly, it should cycle about 2 to 3 times per hour. How long it operates depends on how cold it is outside. In milder temperatures, it may run for 10 to 15 minutes. The colder it gets, the longer the run cycle will be. If your furnace isn’t working correctly, it may start running more frequently.
What causes a gas furnace to short cycle?
Low airflow means the heat exchanger can’t transfer enough heat, and when that heat builds up, it could cause your furnace to short cycle. Here’s what to do: Make sure you keep ALL your vents open—even in unused rooms. 3] Blocked exhaust vents —A gas furnace exhausts certain gases during normal use.
When do you turn off the Furnace Fan?
So, when the switch is working correctly, your furnace fan should turn on several minutes after thermostat calls for heat and turn off several minutes after the heat cycle ends. But if the furnace fan runs continuously, regardless of whether the furnace is heating or not, your furnace fan limit switch is either: