In winter, keeping the interior of your Dallas, GA home warm is a full-time job. Although your furnace does the bulk of this work, your windows, doors, walls, and insulation play an important hand too. With a sufficiently tight home envelope, you can expect fairly short heating cycles with lots of long pauses between them. However, if there are leaks throughout the building, holes in your ducting, or other issues, your heater will run longer or cycle on more frequently. The following is everything you need to know about your furnace’s heating cycles and the breaks that it should be taking between them.

The Length of the Average Heating Cycle

In general, most furnaces run for approximately 10 to 15 minutes before cycling down. With an effective air delivery system and a well-insulated home, this should be long enough to establish your preferred temperature throughout the building. After resting for approximately five to 10 minutes, your furnace will likely cycle on again. Each successive heating cycle restores heat that’s lost through windows, walls, and doors, and through other inefficient building elements. On exceedingly cold winter days, most furnaces run between two and three heating cycles each hour.

Signs Your Furnace Is Too Large or Too Small for Your Home

Longer or shorter than normal heating and cooling cycles are an indication that your furnace is too large or too small for its service area. This happens when HVAC equipment is purchased by homeowners themselves, unlicensed handymen, or HVAC contractors that cut corners. To ensure accurate furnace sizing, we use the Manual J Load Calculation. This calculation accounts for all factors specific to the individual home envelope. It also accounts for household sizes, ceiling heights, and the layout of building interiors.

Great care is taken when sizing furnaces because accurate sizing is essential for optimum performance and a long and relatively problem-free lifespan. Furnaces that are too small for their service areas have longer heating cycles with shorter breaks in between them. Sometimes, undersized furnaces have to run non-stop.

Oversize furnaces cycle on and then rapidly cycle back off. They use massive amounts of heating power and energy in very short periods of time, but they never create even, uniform temperatures throughout homes. Worse still, short cycling causes these units to wear down rapidly and frequently leads to recurring problems with overheating.

The good news is that, if your furnace just started running shorter or longer heating cycles but has provided otherwise consistent performance in the past, sizing is an unlikely culprit. The only time when incorrect sizing suddenly becomes a problem is when major renovations or other structural changes are made to homes.

Leaky Air Ducts and Other Ductwork Problems

Longer than normal heating cycles with limited breaks between them may be the result of problems with your ducting. When HVAC air ducts have leaks, much of the heated air that furnaces produce winds up being deposited in remote, unused areas. For instance, you may have one or more walls that are warm to the touch when your furnace is on, even while the remainder of your home feels cold. This means that the heated air coming from your furnace is being deposited behind your drywall rather than in your living area. If you have leaky air ducts in your garage, basement, or attic, the same could be true for these spaces as well.

To avoid this energy waste and the extra furnace stress that comes with it, you should have your HVAC air ducts inspected annually. For optimum performance, it’s also a good idea to have these features insulated and sealed and to schedule professional duct cleaning every two to three years.

How Having a Dirty or Damaged Heat Exchanger Impacts Furnace Performance

Extended or exceedingly short heating cycles can also be the result of a dirty, damaged heat exchanger. In oil-fired and gas-fired furnaces, this is where exhaust gases go just after fuel combustion. The heat exchanger is where heat is extracted before these gases are routed out of the building. Having an excessively dirty or damaged heat exchanger could cause your furnace to shut down as a preventative safety measure. However, if the heat exchanger is warped, cracked, malfunctioning, or has a light accumulation of debris, you may notice your furnace’s heating cycles becoming much longer.

Many furnace manufacturers issue heat exchanger warranties that last the entire lifespan of their heating equipment. For instance, if your furnace is expected to provide 20 years of service, its heater exchanger is likely warranted for two decades. However, for assured safety, when heating exchangers fail, it’s sometimes best to simply have furnaces replaced.

You May Have Thermostat Problems

Sometimes, changes in the duration and frequency of heating cycles can be attributed to problems at the thermostat. For central HVAC systems that aren’t zoned for customized air delivery, there’s usually a single thermostat that controls temperatures throughout the entire building. This device should always be installed in a neutral, central location. If it’s too close to any heat-generating appliance, it won’t be able to read temperatures accurately. Ovens, open windows, and even certain gaming computers can throw thermostat readings off. If you recently set up a portable heater or added any other nearby sources of heat, you may need to make adjustments in the placement of these things or relocate your thermostat.

Check Your HVAC Air Filter

Another common cause of longer or shorter than normal heating cycles is a dirty, debris-covered air filter. You should check your furnace’s air filter every 30 days and change it every one to three months. When this all-important HVAC maintenance is overlooked or neglected, furnaces have an increasingly high likelihood of malfunctioning and failing.

During heating cycles, furnaces draw in cool, indoor air and pull it through their air filters for particulate removal. HVAC air filters extract loose carpet and textile fibers, lint, pet hair, dust, and other large-sized particulates so that they don’t wind up on sensitive interior components. When air filters are covered with thick, lint-like mats of debris, furnaces have a hard time moving air, and they struggle to get their jobs done. Having a dirty filter can increase or shorten heating cycles. It can also cause furnaces to overheat and shut off.

You can solve the problem by simply replacing your HVAC air filter. However, you should also check for buildups of loose debris at and around your air vents and grilles. Heavy coatings of filter debris are often blown off during heating. These buildups travel through HVAC air ducts and eventually land on vents, grilles, and registers. If you see similar accumulations of debris around these features, wipe them down with a damp cloth and vacuum just behind them.

If you’ve made the mistake of running your furnace with a dirty filter for several weeks or months, turn your heater off and schedule maintenance service. HVAC technicians can remove all trapped materials that have blown off your dirty filter to restore normal furnace functioning. When this maintenance is complete, your furnace should maintain 10- to 15-minute heating cycles with modest breaks between them.

Call the Professionals for All Your Furnace Needs

We help residents of Dallas, GA maintain safe, comfortable living environments. We offer furnace, air conditioner, and heat pump installation, maintenance, and repairs. We also provide water heaters, dehumidifiers, and indoor air quality solutions. If your furnace is running non-stop or barely runs at all, call Precision Heating & Air now to schedule an appointment!

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