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HVAC Education, Buying Tips, Furnaces, Technology

Furnace Maintenance Guide

Furnace maintenance is important to protect your system – the unit itself and the investment in it. Be sure to have an HVAC professional perform an annual furnace service visit in the fall, before the heating season begins, and complete your own maintenance in-between to keep your system in the best condition.

furnace maintenance

Why Is Furnace Maintenance Important?

Furnace maintenance is crucial to keeping your heating system running efficiently. And, one of the easiest maintenance tasks you can do yourself is replacing the air filter. All heating and air conditioning systems have some level of air filtration. From the most basic, 1-inch filter, to pleated 4-inch media filters, to more sophisticated air purifiers, all filter types require some basic maintenance. These filters help with indoor air quality by trapping airborne pollutants flowing through your system. They can also keep your system performing well by helping reduce accumulation of dust, dirt and other particles on internal components like the blower motor, burners and heat exchanger.

Cleaning a furnace and the its air filter is very important. When filters aren’t replaced or cleaned regularly, they can become clogged with debris that can restrict airflow, potentially affecting your comfort and your system’s efficiency. Dirty filters can cause extra wear and tear on furnace components and in more extreme cases cause the system to shut down completely. In extreme cases, a severely clogged filter can result in an overheated and possibly cracked heat exchanger, which can lead to a carbon monoxide leak.

The good news is, checking and changing furnace filters can usually be done in just a few minutes, often with no tools required. Of course, as a precaution, before cleaning your furnace filter, be sure to turn off the furnace either at the thermostat or using the power switch which is typically mounted on the side of the furnace.

In addition, it’s highly recommended to have a regularly scheduled furnace cleaning performed by a qualified HVAC professional. Your local dealer will do a more extensive cleaning of vital components, check furnace heating temperatures, and look for other signs of potential issues that could lead to trouble down the road.

Annual Furnace Maintenance Checklist

Annual furnace maintenance is important for the health of your system, which is why we’ve put together this handy furnace maintenance checklist. These are the steps that your local expert will likely take during your routine maintenance service call:

  1. Check and potentially replace or clean the air filter. For more information, check out our guide to changing furnace filters
  2. Check thermostat operation
  3. Run the furnace in heating mode and record temperature readings from both the return air ducts and the supply or heating ducts, to be sure the heating output is within manufacturer’s specifications
  4. In the combustion chamber, check and clean the burner, crossover, and igniter
  5. Check and adjust the gas valve
  6. On older furnaces, evaluate, clean, and tune the pilot light system
  7. Clean the heat exchanger and check for cracks, holes, or leaks
  8. Inspect and clean the blower and blower motor (your technician might need to remove the blower)
  9. Check for burned wires or high-temperature problems
  10. Inspect the flue pipe and ductwork
  11. Check for leaks in the gas line and other fuel supply components

If you are planning on doing some of the work yourself, most furnace manufacturers will provide guidelines for further information on how to clean your specific model.

furnace maintenance checklist


If your furnace is not working, there are a few things to check:

  • Check to be sure the power switch is turned on
  • Check the thermostat—adjust the temperature up by at least five degrees to see if the furnace turns on
  • Check the circuit breakers or fuse
  • Check and potentially replace or clean the filter
  • Check the fuel supply
    • Oil level in an oil furnace
    • Propane tank level for a propane furnace
    • Ensure gas supply to home and furnace is turned on

For more information, check out our guide to troubleshooting a furnace.

Signs You Need Furnace Maintenance

Sometimes your furnace will let you know it’s time to take a closer look. Whether you want to do your own furnace maintenance or hire a professional is up to you, but keep in mind some of the warning signs are easier resolve than others. Here are some of the more common signs that you need furnace maintenance:

  • Lack of comfort/no heat coming from registers -- if changing the temperature doesn’t help, the problem could be with the thermostat or the furnace itself
  • Higher than normal energy bills – dirty, dusty buildup on components like the air filter or heat exchanger can affect performance
  • Unusual smells coming from the furnace or the registers – the smell of rotten eggs can indicate a gas leak, or a burnt smell might either be dust burning off at the beginning of the season or a more pressing matter like a motor going bad or electrical wiring issues
  • The furnace is making loud or unusual noises – if it’s more than the usual “click and whoosh” of a burner firing up and air flowing through the ductwork, it might be time for a professional inspection
  • The furnace turns on and off frequently (short cycling) - Short cycling can occur if the system’s safety sensors trip, which can be a variety of reasons, including no burner flame detected with the gas valve open or overheating due to poor airflow. Short cycling also can occur if the system is oversized for your home. These are all issues that should be investigated.
  • Pilot light on older units is all yellow or orange, or doesn’t want to stay lighted – this could just mean the pilot needs a good cleaning, or it could be a fuel supply issue

Furnace Maintenance Cost

Furnace maintenance cost will not only depend upon the HVAC contractor, it may also vary according to local labor rates. Costs will also fluctuate depending upon the level of service provided. Many HVAC contractors will offer a more basic furnace cleaning package that might include cleaning and inspection of the filter, blower and combustion compartments, fan blades and condensate lines. These types of appointments are likely available for $100 or a little less. A more extensive maintenance package might also include heat exchanger inspection, checking for CO or gas leaks, checking the operational sequence of the furnace, checking burner alignment and more. These types of appointments will likely average closer to $200, but provide a more thorough review of the system’s condition. Either way, having your furnace regularly inspected and cleaned by a local HVAC professional will help keep your system operating efficiently and reliably for years to come.

Is Furnace Maintenance Necessary?

annual furnace maintenance

If you have asked yourself the question, “is furnace maintenance necessary?”, here’s something to think about: like any mechanical device, automobile or appliance, your furnace requires some basic maintenance to keep performing at its peak. Keeping your furnace cleaned and serviced regularly should result in fewer unexpected breakdowns and more reliable comfort each winter. To keep your home warm and cozy, be sure to inspect and change your furnace filter every 1-3 months (or, per the manufacturer’s recommendations) and stay observant to changes in how it sounds, smells and operates. While performing some DIY maintenance yourself might be convenient and even save you a few bucks, there is no substitute for having your system serviced annually by a qualified HVAC technician like your local Carrier expert. You can find a Carrier dealer in your area using our convenient dealer locator, found on our residential products website.

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