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What Is Short Cycling?

What Is Short Cycling? 

November 29th, 2021


In our previous blog post, we talked about how often and for how long a furnace should cycle on and off. We also dove into some reasons that could cause your furnace to go off this schedule. A common problem that plagues older furnaces, or even improperly installed furnaces, is a process called short-cycling.

Short-cycling is when your furnace, or air conditioner, cycles on, runs for a very short period of time (think 5 minutes instead of the preferable 15), and shuts back off for a few minutes, only to cycle back on yet again. During this time, your furnace is never completing a full heating cycle.

Short-cycling is both the sign of a potential problem with your furnace and will cause further problems. Read on as we explain!

What Causes Short-Cycling?

There are a few different things that cause short-cycling in your furnace, some with easy fixes, and others that will require a phone call to our professionals.

Clogged Air Filter: Did you know that the air filter that comes standard with your furnace needs to be changed out every 1-3 months? There aren’t many maintenance tasks that we recommend homeowners attempt on their own, but this is a small task that you can and should get done.

How often you change this air filter depends on the type of air filter it is and the level of contaminants in your home. But when it gets too clogged up, it restricts airflow and thereby disrupts the communication between your thermostat and your furnace, which is when short-cycling happens.

An Electrical Short: Another possibility is that there is an electrical short somewhere within your furnace or the thermostat. This is a repair need that definitely requires a professional, so be sure to give us a call if you’ve changed the air filter and yet your system is still short-cycling.

Your System Was Improperly Sized: As we discussed in our previous blog post, your furnace should cycle on and off about 2-3 times an hour, and run in 15-minute increments. If your furnace has never followed this structure and has always short-cycled, then we hate to be the bearer of bad news but this means that it wasn’t properly sized, to begin with. The best thing you can do is give our team a call and see what your options are.

Is Short-Cycling Bad for Your Furnace?

Yes, short-cycling is bad for your furnace. It exacerbates wear and tear, reducing the efficiency and lifespan of your furnace and increasing repair needs. In other words, you’ll be paying more for repairs and utility bills and paying for a replacement system far sooner than you should have to.

Can Short-Cycling Be Fixed?

As we alluded to above, yes, short-cycling can be fixed! It may be an electrical issue that needs to be addressed. Or if it’s the case of a clogged air filter, you can “fix” the issue on your own. The only time short-cycling doesn’t have an easy fix is if the system was improperly sized and too overpowered for your home, to begin with. In which case, we’re happy to talk to you about your replacement options!

Look no further than Dayco Systems when you need furnace repair in Kennesaw or one of our surrounding service areas. Contact us today!