Homeowners who own oil- or gas-fired furnaces may experience instances where their heating system cycles on and off as often as every five minutes. This is known as short-cycling, and in this blog, All Climate Heating & Air Conditioning discusses the causes of short-cycling and what you should do if it happens.
What Causes Furnaces to Short-Cycle?
Forced-air heating systems, including furnaces and heat pumps, work by releasing hot air into the ductwork. Sensors in each room detect when the room reaches its ideal temperature, after which the furnace will cycle off. It then cycles back on again when the temperature drops below the set threshold. Furnaces shouldn’t cycle on and off too quickly, however, as heat doesn’t immediately leave a room that’s been properly sealed and insulated.
Short-cycling is usually caused by one of two things: a thermostat malfunction or an improperly- sized furnace. The latter is typically the work of a DIYer or an inexperienced HVAC technician. While a furnace that’s too small will always be red-lining in order to fulfill the heating requirements of a large home, a furnace that’s too large will heat the home too quickly, which later leads to the furnace shutting down much sooner.
Troubleshooting Short-Cycling Furnaces
Now that you know the possible causes, start with the simplest one: the thermostat. Resetting and/or replacing the batteries often “jogs” the heating system’s calibration, which is often enough to stop the short-cycling. Failing that, there are some additional troubleshooting steps one should try before moving on to other potential causes. Room sensors likewise need to be checked for defects.
If the heating system is still short-cycling at this stage, you’ll need to shut your furnace down for several minutes as instructed by the care and maintenance guide. Then turn it back on, set the thermostat temperature a few degrees higher, and see if that makes a difference. If it does, set the thermostat back to the original temperature and wait a few minutes. If it continues short-cycling, you’ll need the help of a certified HVAC technician to definitively identify and fix the problem.
Call All Climate for All Your HVAC Repair Needs
All Climate is your number one provider of all HVAC repair, installation and maintenance services. Give us a call at (425) 361-0126 or fill out our contact form.