When the colder weather arrives, there is nothing quite like the feeling of relaxing in a warm and comfortable home. At this time of year, we rely on our furnace to keep our homes warm without breaking the bank. But, what if your furnace isn’t running as it should or the energy bills seem to be too high? Do you understand how long your furnace should be running and the frequency of the heating cycles? In this article, we will take a closer look at these topics to help you gain a greater appreciation for the needs of your furnace.

Understanding “Average” Furnace Running Cycles

As you may notice from the title of this section, there is no real “average” length of heating cycle that we can cite as a definitive figure. The reason for this is that the length of your heating cycle can vary a great deal and this is based on two external factors.

The most important factor will be the external temperature and this is true even if you have adequate home insulation. Although insulation minimizes heat loss, it doesn’t prevent it entirely. So, when the air is colder outdoors this causes the indoor temperatures to drop earlier and this will extend the running time of the heating cycle to compensate.

The second key factor is temperature settings on the thermostat, which you can think of as the brain for your entire heating and cooling system. As the temperature reaches the operating limits of your furnace, it will need to run for longer. This happens because the furnace needs to maintain that temperature throughout the home. So, when you set  the temperature on the thermostat higher it extends the heating cycle length.

Both of these factors play a part in the length of the heating cycle even if your furnace is working at optimal efficiency. But, as a benchmark you can consider a rough average heating cycle length of approximately 10-15 minutes if neither of those extreme factors was involved. This is unlikely, but to put this into real terms your furnace will probably need to be running for 2-3 times per hour to keep your home at the desired temperature. This is true if your home has at least an average level of home insulation.

If you notice that your furnace tends to run for shorter or longer times than this average, don’t panic. The furnace may not necessarily have a problem or you may need to schedule some professional maintenance for the unit.. But, if the furnace is running with short or long heating cycles when the weather conditions are milder it’s time to contact your local HVAC specialist to investigate.

6 Potential Heating Cycle Problems Explained

If there is no obvious cause of the aberrant heating cycle lengths then there could be an issue that needs to be identified and fixed. A furnace that is behaving in this manner is more prone to failure and it will consume more energy which drives up your utility bills. Let’s take a look at six potential reasons why the furnace may be behaving this way, they are:

1.   A Dirty Furnace Filter

The furnace filter is an often overlooked and yet critical component that must be clear for the heating system to work efficiently. The filter can become clogged with dust and debris which forces the system to work harder to push the air through. This can even cause the heat exchanger to overheat because the airflow is required to regulate the temperature. This is a fix for anyone with very basic DIY skills and the full instructions are detailed in the owner’s manual for your furnace.

2.   Exceeding the Heating Capacity

Every furnace is designed to produce a set amount of heating capacity during each and every heating cycle. If this heating capacity is not used, it can cause the furnace to overheat which triggers the safety systems. The furnace will turn-off early to protect the components in your heating system.

3.   An Incorrectly Sized Furnace

If you’ve recently had the furnace installed, this phenomenon may be the result of a unit that is incorrectly sized for your home. If a furnace is too large or small, it can heat or cool the home too quickly which confuses the system. This can lead to “short cycling” which is when the HVAC system turns on and off again rapidly. This can place a great deal of extra strain on heating and cooling equipment leading to frequent failures.

4.    A Faulty Heat Exchanger

If you have a gas furnace the heat exchanger takes the heat from the flames and transfers that to the incoming airflow. This treated air is then distributed throughout your home via the ducts to make each room warmer. If the heat exchanger is cracked, warped or failing for some other reason it will extend the heating times considerably. This will consume more energy, but more importantly it’s also a fire risk and it should be looked at by a local HVAC specialist.

5.   A Malfunctioning Thermostat

The furnace cycles can be affected by the thermostat, if it’s relaying the wrong information to your heating system. The thermostat contains a sensor that may sense the wrong indoor temperature if it is dirty or failing. If your thermostat has a failing battery this can also cause it to send the wrong signals leading to intermittent heating cycle times.

6.   Badly Designed Ducts

If the ducts are badly designed or poorly installed, it can lead to an incorrect flow of air to the heating vents. This can affect the timings for the heated air to travel throughout your home to bring it to your desired temperature. This is inefficient, but the main problem is that it can cause the furnace to overheat which could turn the unit off to protect the components.

What is the Right Course of Action?

If your furnace has shorter or longer heating cycles, it can lower the performance, drive up your energy bills and damage the components. Avoiding high utility bills and expensive repairs is possible if you adopt a proactive approach to the problem. If you are worried about your furnace, check and change the furnace air filter. If this doesn’t work, investigate the thermostat, clean the sensor and change the battery. If the problem persists, contact your local HVAC specialist and get them to investigate the problem.