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. If you notice your furnace turns on and off frequently, it’s called short cycling. And that can make your home less energy efficient.
In general, short cycling is caused by one of three things.
Your gas furnace has a heat exchanger that heats the air supply that flows into your home. If this overheats, it will shut down to protect the components from further damage. As the heat exchanger cools, it’ll turn back on to attempt to heat your home. This creates an endless cycle of turning on and off.
The problem lies with creating too much heat inside the furnace. With this amount of buildup in your furnace, it runs the risk of ruining the heat exchanger, which can run into the thousands of dollars depending on your system. This is usually caused by:
- Dirty air filters
- Closed registers or vents
- Blocked registers or vents
- Blocked exhaust pipes
All can be potentially dangerous to your furnace, so it’s important to get them fixed as soon as possible.
The thermostat controls how often your furnace will turn on and off. Think of it as the brain of your system to tell it what temperature your home should be. If it malfunctions, it may cause your furnace to operate incorrectly.
Take a look at your thermostat - does it appear to be working correctly? Does the display light up? Does the temperature readings change as the furnace turns on and off?
You should also look at the thermostat location. Is it near a register? Is it near a window that allows sunlight to filter onto it and cause false readings? If you have a question, a professional can help you determine if it’s set up correctly.
Do you have a new furnace? If the contractor installed a unit too big for your home, it could be short cycling.
Furnaces are sized according to how much heat it can put out in an hour. If the system is too big, it will heat that level too quickly, short cycling as it reaches the desired temperature.
This often happens with “good deals” - where a technician doesn’t perform proper testing to make sure they install the correct size of furnace.
Unfortunately, if you don’t have a proper warranty in place that allows the company to come back out and install the correct size, the cost may be on you. But in the long run, a proper sized furnace will operate better, provide proper energy efficiency, and heat your home to a comfortable level.
Have additional questions about how frequently your furnace runs? Give us a call today.