A furnace doesn’t run continuously when it’s powered on. It works in a process called “cycling” in order to be effective as well as energy efficient. It kicks on when the thermostat detects that the indoor temperature is lower than desired, then turns off when it has reached the right level. This helps it maintain a balanced temperature to ensure your comfort.
How Long Is a Heating Cycle?
A normal heating cycle commonly runs several times in an hour, but the exact number depends on several factors that are unique to your situation; for example, how cold it is in your location and how big your home is. The kind of furnace you have in your home — one-stage or two-stage — and the location of your thermostat also have an influence on how many cycles it takes over an hour to keep your home warm.
The architecture of your home also plays a role in the cycling of your furnace. The amount of insulation it has and the type of windows that are installed, together with your choice of window treatment and even the age of your furnace, also play a part. Some other variables may also be at play, such as how many people are in your home at any given time, what appliances are running and contributing heat and whether or not your attic is properly ventilated.
A furnace can complete two to three cycles in an hour, though at times this number may range anywhere from three to 10 if it’s especially cold outside.
What If It Seems to Cycle Too Frequently?
Depending on how many of these influencing factors are in the right or wrong condition [not enough insulation, windows aren’t at least dual-pane with an inert gas fill between panes, attic vents are covered during the winter (this is bad), the furnace is too big or too small for your home, etc.], your furnace shouldn’t cycle too frequently.
You should call a professional to determine whether or not your furnace is cycling normally. However, these factors surrounding your furnace alone can give you some idea:
The furnace is too small, so it needs to turn on more frequently to heat up the space.
The furnace is too big, so it heats up your home too quickly, forcing it to stop almost immediately. However, it can’t heat your home evenly, so it has to turn on more frequently.
The furnace is old and inefficient, so it doesn’t cycle normally anymore.
The thermostat has an issue or is positioned next to a window where it’s exposed to the sun’s heat.
The thermostat’s flame sensor is dirty, leading to cycles that last only a few seconds at a time.
Whatever is causing your furnace to cycle abnormally, it’s bad for your indoor comfort and health, the furnace’s lifespan and its energy consumption. It’s best to hire a professional HVAC technician to check your furnace and schedule it for repairs or perhaps even a replacement.
Call Climate Systems Heating and Air Conditioning at (724) 935-3900 or tell us about your air purification or HVAC requirements here.