There are multiple reasons why your furnace is short cycling. These could include a dirty filter, blocked vent, or malfunctioning flame sensor.
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. Turn the furnace on again.
Dirty air filters are one of the most common reasons behind furnace short cycling.
Blocked vents or a clogged air filter may cause your furnace to run and then shut off too early. It's easy to fix these issues on your own. You should change your furnace filter at least once every three months. Follow our guide to do it yourself.
If your thermostat isn't working right, your furnace won't work right either. A malfunctioning thermostat can lead to short cycling, no heat, and rooms that never quite feel warm enough. That's why it's important to address common thermostat problems before they turn into big, and expensive, headaches.
Something as simple as a dirty air filter can cause your furnace to short cycle. Contaminated air filters block airflow, and eventually, cause a backup. This means that warm air will remain in the furnace instead of distributed to the different areas of your home.
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.
HVAC maintenance companies explain that a furnace will normally perform an average of two to three cycles in an hour, with each cycle lasting 10 to 15 minutes. But to keep temperatures at a comfortable level during cold weather, a furnace might need to increase this range to three to 10 cycles.
There is a work-around to waiting. If there is no safety risk (like a gas leak), a furnace can be reset to bypass this wait. Turn off the furnace's power switch and wait 10 seconds before turning it back on.
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. Short cycling can also be used to describe a furnace that turns on and off too often.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
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.
A clogged furnace air filter will negatively affect the airflow throughout your house and HVAC system. The lack of fresh air in your furnace will cause the heat exchanger to become too warm and deactivate. Dirty filters indirectly cause short cycling issues and will make it hard to keep your home warm.
Your furnace may be turning on and off quickly due to issues like a dirty air filter, overheating, a malfunctioning thermostat, or a clogged vent. These problems restrict airflow, causing the system to short cycle and not operate efficiently.
Short Cycling Causes
Here are a few problems that may cause furnace short cycling: Air Filters – Severely dirty air filters may cause this issue because they restrict the airflow to your system. Replace the filter and set a reminder to do this regularly. Blocked Vents & Registers – This is another easy fix you can try.
No fixed duration for how long a furnace should stay off between cycles. But, aiming for three to six cycles per hour in cold weather conditions is a good guideline.
Ask twenty professional HVAC contractors the question, “How Much Does A New Furnace Cost?” and you'll probably get the same answer... “It depends.” On average, the cost of a new furnace can range from $2,000 - $14,2001. However, factors like furnace efficiency, type, size, and much more can impact this range.
If your furnace is having trouble igniting or maintaining a consistent flame, it can lead to short cycling. Common ignition issues include: Dirty or malfunctioning flame sensor: A dirty flame sensor can't detect the presence of the flame correctly, causing the furnace to shut down as a safety measure.
Most furnace flame sensors cost less than $20, but if you opt to have a professional HVAC technician make the repair, you can expect to pay between $75 and $250. Need help replacing your flame sensor?
If it's still not operating properly, you should call for furnace repair. How Often does it need cleaned? Most experts recommend cleaning the flame sensor once a year.
If your air conditioner's short cycling problems are not solved by fixing the evaporator coils, the filters, or the refrigerant levels, this could be the root cause. You should have an HVAC professional replace the low-pressure control switch with a brand new one.
First, turn off the power supply to the furnace by turning off the breaker in the circuit box. Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious, as the housing may be hot.
The thermostat may be improperly set, the batteries may be weak or dead, or the thermostat itself may be defective. To fix this, start by changing out the thermostat's batteries with fresh batteries. Check the lower end of the thermostat's temperature settings. If set too high, the furnace will frequently cycle on.