Understanding Furnace Maintenance

Just like with any other mechanical system, proper furnace maintenance is crucial to keeping the system performing properly and ensuring a long service life. Maintenance for furnaces isn’t necessarily complicated or difficult, but there are steps to follow and a schedule to be mindful of. We’ll talk about some of the steps involved in annual furnace maintenance, and how it can pay off in terms of reliability, safety, lower utility bills, and longevity. It’s something that saves service calls and enhances the comfort and peace of mind of the homeowner.

Gas Furnace Maintenance

Here’s a quick rundown of a typical process for maintenance on a gas furnace:

  • Flip the electrical switch to Off and remove the furnace’s access door. Remove the burner cover, if applicable (usually held in place with two screws).
  • Flip the switch back to On and activate the burner by turning up the thermostat. Inspect the flames from the burner — they should be even in height and blue. A yellowish flame indicates a dirty burner. Don’t blow on the flames or breathe on them, since the extra oxygen will turn a flame yellow. Dirty burners should be serviced by a professional.
  • Use the wand attachment of a vacuum cleaner to thoroughly clean the combustion area of fuzz and soot. You can access some of the more hard-to-get-to parts of the furnace by taping a 20-inch length of PVC drain line to the vacuum’s hose. It’s important to keep an eye out for soot as well; an excessive amount of soot is a sign of poor combustion.
  • Remove the squirrel cage blower for cleaning. If you have to remove the control panel to get the blower out, remove the screws that hold it in place and then suspend it by a piece of wire rather than letting it dangle from its own electrical connections. The blower is usually mounted with a couple of bolts that are easily removed with a socket wrench.
  • Carefully clean the blower and squirrel cage with a brush and vacuum, being sure to not damage or move any counterweights on the fan blades. Only clean the blower if you can do it thoroughly – a partly cleaned blower could be put out of balance.NuComfort Gas Furnace Maintenance
  • Change the filter; a cheaper fiberglass filter will be fine. A more restrictive filter can impede air flow, putting stress on the blower motor and making the system less efficient.
  • If the system is equipped with a pilot rather than a hot surface igniter or electronic igniter, clean the pilot by blowing on it through a drinking straw or using “canned air” for cleaning computer keyboards. A dirty pilot can cause the system’s flame sensor or thermocouple to deliver a false reading that indicates the pilot isn’t lit.
  • Locate the flame sensor, remove it from its mount and carefully clean, using fine emery cloth. Don’t use any chemicals or soap to clean this delicate part.
  • Hot surface igniters are common on modern furnaces, rather than pilot lights. To clean the igniter, use the straw method without removing the igniter; this is a very fragile part that’s easily damaged.


Other Maintenance Details


Of course, there’s more to your HVAC than just the furnace’s combustion chamber. These are other details you shouldn’t overlook in the course of a furnace tune-up and maintenance:

  • Many furnaces still use a belt-driven blower, just like the fan belt on older vehicles. Check the belt for fraying, cracking or other signs of wear and damage. If the belt’s pulleys are adjustable for tension, make sure that the belt has ½” to ¾” deflection – if there’s more slack in the belt than that, it may be worn to the point of needing replacement.
  • Some older blowers have a port or fitting for lubricating the motor’s bearings. If your furnace is so equipped, remove any seals or plugs and lubricate with a few drops of light machine oil, such as 3-In-1. Replace the seal or plug.furnace ductwork repair
  • Some systems feature furnace ductwork that doubles as A/C ducts as well. Check to see if there are any dampers that need adjustment; many have a Winter setting and Summer setting. Two-story homes are often equipped with separate supply trunks for upstairs and downstairs. Adjusting the damper handle on each supply trunk can enable you to direct more warm air downstairs and less for the second story.
  • Inspect all the ducts for leaks. Locate the furnace’s draft hood and hold up a lit stick of incense; the smoke should be drawn up through the hood. If you find any leaks in the ductwork, cover them with special metallized adhesive tape that’s available for just that purpose. When the exhaust pipes and vent stacks are cooled off, get a look at them for any powdery white residue that could indicate corrosion. Give the water heater’s vent stack a squeeze; it should be firm but slightly flexible and yielding.
  • Inspect all the registers and floor vents in all rooms for good flow and lack of obstruction (including dust and fuzz).


Signs of Trouble

These are all indicators that something’s amiss and you might need a call from a service tech:

  • Short cycling: Short cycle is when the system only runs for three to five minutes at a time. A system that’s short cycling might have a thermostat that’s out of adjustment, or a heat exchanger that’s overheating and shutting off the burner automatically to prevent any damage.
  • Irregular flames: As mentioned above, the flames from the burner should be blue and a uniform height all the way across. Flames that are uneven, yellow or leaning toward the back of the unit could indicate a burner that’s in need of cleaning, or even a cracked heat exchanger.
  • Soot deposits: As mentioned above, soot deposits inside the unit can indicate poor combustion.
  • Odd noises: If the homeowner hears buzzes, rumbling, vibrations and other unusual noises from the ductwork and furnace, that’s a sign of trouble that needs inspection.
  • Respiratory problems: Symptoms like a chronic sore throat, headaches, sneezing or asthma-like shortness of breath can all indicate poor indoor air quality and a heightened level of particulates in the home. The causes can be as simple as a dirty filter, or something more involved.

Additional Help

If you have any questions or would like to consult with our team, we’re here for you. We strive to go above and beyond to service our customers. We dedicate ourselves to fostering close, ongoing relationships in order to help customers grow their business. While offering only the highest-quality HVAC equipment and parts, we can provide you with the advice and expertise you need. Contact Us!

NuComfort LLC is a wholesale distributor of both commercial and residential HVAC systems. We also stock a full line of accessories and replacement parts. We have a long history of satisfied customers, and are ready to serve you from our three Chicagoland locations in Glendale Heights, Chicago and Crestwood.