When the weather turns colder, we rely on our furnaces to keep our homes warm and comfortable. In many cases, the furnace has not been used for a while and strange behavior may be observed. For this reason, we recommend an inspection before the start of each heating season to ensure that the performance and efficiency are optimal. One of the more annoying problems to arise is when the furnace turns on and then off again rapidly and this is known as “short cycling”. In this article, we will explore this subject in more detail and explain how to fix the problem.

Understanding Short Cycling

Short cycling can occur in your heating and cooling systems and fixing this should be a priority. Aside from the obvious annoying nature of this problem, it is also very hard on your HVAC system. When the components are turned on and then off again rapidly and repeatedly it can cause damage to sensitive components. This can lead to an unexpectedly high repair bill and in extreme cases, you may need a system replacement. Another reason for concern is that short cycling consumes a lot of energy for no reward and so it will drive up your utility bills. When short cycling occurs, it is often accompanied by a clicking noise and there are a number of possible causes. It’s important to realize that the components are attempting to function and that is a comforting thought. The only way to identify the cause of your short cycling problems is to contact your local heating and cooling specialist. They have the training and experience to find the fault and fix it for you.

5 Common Causes of Short Cycling Explained

If you’re unsure about contacting an HVAC specialist immediately, there are a few things that you can do with a few basic DIY skills and the owner’s manual. Troubleshooting may help you to fix the problem without professional intervention if you’re lucky. Let’s take a look at five common causes of short cycling in more detail, they are:

1.   A Dirty Furnace Filter

The furnace relies on a steady supply of air to keep the internal components cool and working efficiently. In fact, the furnace has a safety system in-place that will turn the furnace off if the internal temperatures are too high. This may be the reason why your furnace is turning on and then shutting off every five minutes or so. The good news is that this problem is very easy to fix with no special skills and it only takes a couple of minutes. The process is detailed in the owner’s manual for your furnace, locate the filter, check it and if it’s dirty replace it with a same model number unit. Remember that the primary purpose of the air filter is to protect the system and any improvements to the indoor air quality (IAQ) are secondary in importance. Establish a new routine with a monthly check of the furnace air filter and you can avoid a number of problems.

2.   Inspecting the Thermostat

The thermostat is the central brain of your entire heating and cooling system. If the problem lies in your thermostat, it could be sending false messages to the rest of the system. A common issue is a malfunctioning or dirty thermostat sensor that sends the wrong temperature settings to the furnace. This can also occur if the thermostat has been placed in a place that’s too warm such as a sunny window where it may feel warmer. When the furnace receives this information, it may short cycle as it attempts to bring the home up to the correct temperature and then realizes that it isn’t necessary. Another possible culprit is a failing battery and replacing this may correct the problem. If the problem persists, call a local heating specialist and ask about a thermostat upgrade.

3.   Check the Furnace Blower

This is the component that pushes the treated air through the ducts and out of the heating vents. This fan is also a critical part because if it fails the heat will stay inside the furnace. As we mentioned earlier, when the furnace gets too hot it will shut down automatically and this is a built-in safety feature. There is an easy way to test that the furnace blower unit is working properly. When the system is running, place your hand over the heating vent and if you cannot feel much airflow the problem may be the furnace blower. Replacing this unit is the best approach and the work should be carried out by your local licensed and certified heating specialist.

4.   Inspecting the Flue

The flue is that vent that you may notice on the roof and its purpose is to remove excessive hot air from inside the furnace. This can be checked if you have good DIY skills, a tall ladder and you are familiar with working on rooftops. If you decide to continue, make your way to the roof and check the flue for signs of heated air and steam as the furnace is running. If you cannot see any signs of vented heat, take a look in the flue for any indications of a clog that is blocking the pipe. This could be leaves, twigs, litter, or other debris that seems to collect in many locations outside your home. Take care, the flue may be hot and you may want to let it cool down before you reach inside. If you are not comfortable performing this task yourself, contact your local HVAC specialist for expert help.

5.   Check the Furnace Size

Many people install the largest furnace they can afford because bigger is always better. But, when it comes to HVAC systems, this is the wrong approach because the units need to be carefully matched to the size of your home. There are other factors to consider too, such as the orientation of the home, the insulation levels, the number of windows, and more. These factors are included in a complex load calculation that should be made by a qualified heating specialist. When the HVAC system is too large or small, it can cause short cycling because the heating or cooling is too fast or ineffective.

If you are experiencing short cycling problems, contact your local HVAC specialist today.