Common issues include: Old wiring or dead batteries: Replace batteries or old wiring to ensure accurate temperature readings. Thermostat location: If your thermostat is too close to a heat source (like sunlight or a heat register), it can misread the temperature and cause your furnace to keep shutting off.
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.
There are multiple reasons why your furnace is short cycling. These could include a dirty filter, blocked vent, or malfunctioning flame sensor. You can switch for a clean furnace filter, or have your HVAC technician resolve a more complicated issue.
One possible issue for a furnace running only for 5 minutes could be a malfunction with the thermostat. The thermostat is responsible for regulating the temperature in your home and communicating with your furnace to turn on and off as needed.
This can be caused by a couple of possibilities. It's not that you're blower is out of sync, it is either going bad or if this is an older furnace with a fan-limit switch, it is cooling down the heat exchanger too fast (or the unit is underfired) and the fan switch is turning it off.
To begin, ensure that all the filters of your furnace are clean. Also, get the filters replaced every few months to ease the burden on your HVAC system and ensure that fresh air comes filtered into your home. Another common cause of your furnace turning on and off after a few minutes is a faulty pressure switch.
Common issues include: Old wiring or dead batteries: Replace batteries or old wiring to ensure accurate temperature readings. Thermostat location: If your thermostat is too close to a heat source (like sunlight or a heat register), it can misread the temperature and cause your furnace to keep shutting off.
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.
With an effective air delivery system and a well-insulated home, this should be long enough to establish your preferred temperature throughout the building. After resting for approximately five to 10 minutes, your furnace will likely cycle on again.
Short cycling is a common sign of a bad flame sensor. The sensor thinks that there isn't a flame, so it shuts off the gas as a safety mechanism. Except, there is a flame and without the gas to supply it, it dies. This is a frustrating problem, but an HVAC technician can fix it.
Insufficient airflow or insufficient gas pressure. A defective, malfunctioning ignition board, flame sensor, light switch, thermostat, thermocouple, fan limiter, or draft inducer fan. The drainage line is blocked, resulting in a full condensate pan. Temperatures are so low that the furnace cannot stay lit.
On your thermostat, look for the fan settings. There should be two, “ON” and “AUTO.” If it seems like your furnace won't turn off, the thermostat may be set to “ON” for the blower. Toggle the switch to “AUTO” so your furnace's blower fan only runs during a heat cycle.
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.
What Causes Short Cycling? Furnaces have built-in safety systems that prevent dangerous situations like fires, carbon monoxide leaks, or gas leaks. The most likely cause of short cycling is the fan limiter, which prevents fires and furnace damage by shutting the system down if the heat exchanger becomes too hot.
Luckily, a few causes of short cycling are easy to fix yourself. An incorrectly sized unit, refrigerant leaks, and other issues demand a professional repair. If your short cycling issues are due to air filter problems or a frozen evaporator coil, you can address the problem before calling the professionals.
Having a dirty air filter in your furnace can cause short cycling. While a faulty flame sensor will lead to an immediate shut-off, a dirty filter will allow your furnace to run for several minutes and then shut down. You might notice that the air being pumped out of the heat grates is significantly hotter than normal.
One of the leading causes of short cycling is an oversized furnace. If your heating system is too powerful for your home's heating demands, it will quickly heat your living space, causing the thermostat to reach the set temperature and signal the furnace to turn off.
Slowly turn the thermostat from off to heat and increase the temperature. Both the thermostat and furnace should make a sound. The problem lies in the appliance that does not make a sound.
Flame Sensor Is Corroded Or Soot-Covered
A dirty flame sensor could be why your furnace keeps shutting off. The flame sensor is a safety device designed to turn off your furnace if no flames are detected, protecting you against dangerous gas fumes.
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.