Why Is My Minneapolis Furnace Running Short Cycles?

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It’s getting to that time where the furnace should come on to prevent the chill in the air from getting in your home. Turning on your furnace is one thing, but finding out why issues are happening is another thing. If you want to learn more about how to safely start up your furnace, check out our blog on the six steps to starting up your furnace. Once your furnace is turned on, there are some issues you will want to watch for. One of those is if your furnace is running short cycles. If that happens, there could be several issues that could be causing it.

What is a short cycle?

A short cycle is when your furnace only runs for a short time without getting up to the temperature your thermostat is set at. In most cases, a furnace will run often as it short cycles because it never reaches the programmed temperature. This leads to various problems with your furnace and your comfort. Fixing the issues that cause short cycling are important and should be addressed promptly. There are some issues that you can fix on your own before calling an HVAC professional.


Dirty air filters

There are a lot of issues that dirty air filters can cause and short cycling is one of them. When the air filter is clogged, the air is blocked before it can get to the heat exchanger. Because there is not enough warm air getting into your home to heat it, the sensors will indicate that your home is still cold and turn up the heat exchanger. If that keeps happening, the heat exchanger will overheat and turn off for your safety. Thankfully, this is easy to fix. All you have to do is change your air filter.

Thermostat problems

Your thermostat records the temperature in your home to tell your furnace how much to heat the air that goes into your home. When it is not working properly, the information from your thermostat to your furnace is wrong or cut short so that your furnace short cycles. Depending on the issue with your thermostat, there are a couple of different ways this can be fixed. Start by checking the batteries. Short cycling can mean that your thermostat is low on battery, so changing that out can help. Another issue your thermostat could be having is that there is a vent or heater right by your thermostat, making the temperature seem higher than it is in your home. Remove the heater or close the vent to fix the issue. The last issue could be that your thermostat needs to be rewired. If your thermostat needs to be rewired, make sure to hire an electrician like our master electrician.

Bad flame sensors

In a natural gas furnace, the flame sensor detects there is a flame for the gas to be ignited by. When that sensor is damaged or dirty, it blocks the flame from getting to the sensor, shutting off the gas so that the flame doesn’t heat up the air as well. As the dirt on the sensor moves or as it malfunctions more the gas will come on and off. That makes the furnace heat and cool frequently and short cycle. This can be cleaned off or replaced depending on the issue it has.

Clogged pipes

Similar to dirty air filters, clogged pipes restrict the airflow in your furnace. There are a couple of places you’ll want to have checked if you are concerned about airflow. You’ll want to check the exhaust vent, air ducts, heat grates, and flue. Your HVAC contractor will easily be able to check out more areas to make sure everything is cleaned thoroughly. Our HVAC technicians make sure to check the air flow in your furnace during the 21-point inspection.

Oversized furnace

A furnace that is too large for your home heats up your home quickly, but it will have to frequently turn off to keep the temperature of your home from going over the one programmed on your thermostat. This can also cause short cycling and put more stress on your furnace. If you have any questions about the size of your furnace, give us a call.

Furnace inspections are important for making sure there aren’t any issues when turning on and running your furnace. Give us a call to schedule an appointment to get your furnace ready for the winter.