If your furnace keeps turning on and off repeatedly, cycling too quickly between the heating cycle and the resting or cool-down period, you have a short-cycling problem. Short-cycling wastes energy and actually damages the furnace by causing it to run at above normal temperatures for an extended period of time. This can lead to breakdowns and costly repairs.
As you might have noticed, the furnace in your home turns on and off several times per hour, sometimes even more frequently. Depending on how cold it is, it may do so even more often—even hourly. This cycling is necessary because climate control isn’t like flipping a switch, and a “constant” temperature doesn’t really exist as far as your furnace is concerned. When it happens too frequently, though, your furnace is likely out of whack.
The furnace in your home is just like any other machine, in the sense that it has moving parts that need to work in a certain way for your home to be warm. When something goes wrong with the way it operates, problems are bound to arise. This can lead to gaps in heat or hot and cold spots in your home. Having regular service performed on your furnace can help prevent short cycling from happening and other serious issues from developing within the system…
Causes of short-cycling
Short-cycling is a natural result of improper furnace operation, and there are many reasons why it happens. Improperly sized HVAC systems, air leaks, and dirty air filters are only a few of the most common causes of short-cycling. Let’s examine a few of the problems you might encounter below.
Filthy air filters are often the cause of short-cycling. Dirty filters restrict airflow to your furnace’s heat exchanger, which can cause it to overheat and shut off prematurely. The furnace will restart when it has cooled, causing the short-cycling problem to continue.
Like any piece of mechanical equipment, your thermostat is fallible, and may need attention periodically. If your thermostat isn’t working properly, it may be telling the furnace to shut off prematurely.
A common cause of short cycling is poor insulation or air leaks that allow heated air to escape, so check your windows for any signs that they’re open or need maintenance.
You should also check the seals around your windows. If air is leaking out, you may need to apply caulk and/or weather stripping around the frames.
Some causes of short-cycling may be the blower motor, the flue, or the flame sensor. If the blower is not working, your heat exchangers will not be able to warm the air and they could become too hot, causing the furnace to shut off.
HVAC systems that are mismatched to the home they serve waste energy and wear out more quickly, which will cost you money in the long run. An HVAC professional can help you identify the problem and fix it.