A Simple Guide to Gas Furnace Maintenance

Key Points

• Preventative furnace maintenance is crucial for efficiency, consistency, and safety. Properly maintained systems save money and improve air quality.
• Perform routine furnace maintenance annually. The best time to schedule furnace servicing is in autumn, before heavy use in winter.
• Many parts in your furnace may need repair or replacement, even if performance has remained stable.

When was the last time that you had a licensed furnace technician take a look at your furnace? Even if your heating system is running as expected, don’t be complacent. You should have a qualified professional perform routine maintenance. Routine maintenance improves efficiency, ensures safety, conserves energy, and maximizes savings. Neglecting regular furnace maintenance, even if your system is operating as intended, is a recipe for costly repairs or replacements. Curious about what goes into gas furnace maintenance? Use this guide to learn about furnace inspection and maintenance so you can feel confident about what it involves, when to seek help from a qualified furnace technician, and why it matters.

Why Is Preventive Furnace Service Essential?

If you want a safe, effective, and quiet furnace, maintaining a regular service schedule is non-negotiable. You may be wondering: Why should I call in a technician if my furnace isn’t raising any red flags? Annual preventive maintenance isn't about fixing problems that already exist: it's about preventing future issues from developing. Preventive furnace servicing has several advantages, including the following.

Preventive Maintenance Saves You Money

Waiting until noticeable issues appear can be more expensive than performing regular maintenance. Preventive furnace service reduces the risk of severe breakdowns and extends your furnace’s life. In most cases, simple upkeep is much less expensive than emergency repairs. Regular maintenance also keeps your furnace running at peak efficiency longer, saving you money on your energy bills in the long run.

• • Preventing costly emergency repairs
  • Extending your unit's lifespan
  • Saving money on your energy bills
  • Keeping you and your family safe from harmful gases like carbon monoxide
  • Filtering out contaminants for clean airflow

Preventive Maintenance Boosts Your Air Quality

On average, Americans spend 90% of their time indoors, but air pollutants can be two to five times more concentrated inside. Substandard indoor air quality is a grave health concern for everyone, though those with asthma, respiratory problems, or immunodeficiencies are the most vulnerable. Dust, pet dander, mold, smoke, bacteria, and viruses can enter our homes at any time, working their way into the HVAC system and circulating through the air ducts, eventually entering your body with each breath. Preventive maintenance protects your health by mitigating how many of these allergens and pollutants manage to exit the furnace. An HVAC professional will ensure your furnace air filters are clean and functioning, making your indoor air as pure as possible.

Preventive Maintenance Keeps You Cozy All Year

Gas furnace maintenance ensures your system delivers even, steady airflow throughout your home. An effective furnace and clean ductwork will withstand extreme temperatures, guaranteeing every room is comfortable.

Preventive Maintenance Protects Your Home and Family

A malfunctioning furnace can mean disaster for your home, including frozen or burst pipes, flooding, and even structural damage. Catch issues before they become emergencies with regular inspections and preventative maintenance, which will also reduce the risk of carbon monoxide, keeping your family safe.

Preventive Maintenance Is Beneficial for the Environment

Preventive maintenance ensures your HVAC system can uphold its full efficiency. An inefficient system wastes fuel and releases more harmful fumes into the air. Operating on as little fuel and electricity as possible lessens your furnace's impact on the environment while saving you money on monthly energy bills.

How Often Should Furnaces Get Maintenance Checks?

If you have a gas furnace, you need routine checkups. Ideally, you should seek maintenance once a year in the fall. As the leaves change and the temperature starts to drop, your furnace could be in for a shock. Depending on where you live, it might have been months since your furnace last kicked on. Winter is on the horizon, and the coldest season of the year in the northern hemisphere will put your system through its paces almost every day.

Think about how you would handle a vehicle in a similar situation: If you let a car sit unused in a garage all winter, you'd want to get an inspection before taking it across the country on a summer road trip. The same principle applies to your furnace– a professional should ensure everything is in top shape before winter approaches.

What Gas Furnace Parts Need Regular Inspections and Maintenance?

For an in-depth breakdown of what servicing looks like, check out our furnace maintenance guide. Keep in mind that some components require extra attention during the process. Here are parts of your furnace you may need to have tuned up or replaced during routine maintenance.

Heat Exchanger

The heat exchanger is an essential element of your furnace that keeps combustion gases separate from the air you breathe. This component releases warm air inside and vents any fumes created in the process safely outside. Continuous heating and cooling expand and contract this component's metal walls. Over time, the metal can wear thin. Imagine bending a paper clip back and forth until it snaps — the same happens to your heat exchanger over several years. A worn heat exchanger can mean combustion gases, including carbon monoxide, are released into the home. Breathing these fumes can be fatal, according to the CDC, or the Centers for Disease Control. To keep you and your family safe, you need a professional to check for invisible gas leaks, cracks, or deterioration in the heat exchanger.

Burner

Gas combustion occurs in the burner, producing heat for the heat exchanger. An unclean burner can result in inefficient combustion, soot buildup, or condensation. The flame coming out of your heating unit should be steady and blue. If the flame is yellow, the burner may be dirty. These issues can drive up your energy bills and shorten your furnace's lifespan. At least once a year, a professional should remove and clean the furnace's burner. They'll also test the quality of the burner flames and make adjustments as needed to maintain efficiency.

Pilot Light or Ignition

Older furnaces have pilot lights, whereas modern furnaces use automatic ignition systems. An automated ignition system uses either an electrical spark or a resistance heating element to ignite the fire when needed. Since it only burns on command, modern furnaces using automated ignition conserve fuel and mitigate some of the safety concerns created by pilot lights.

A pilot light is always burning, requiring a small but steady stream of gas to stay lit. Several issues can arise with the ignition. A weak flame can quickly extinguish, shutting down the furnace. A faulty or dirty flame sensor will fail to detect a flame. The gas valve or pilot opening can clog. In any of these instances, a professional will need to clean elements and make adjustments.

Gas Line

As their name suggests, gas lines transport gases in and out of the furnace system. These gases are flammable and dangerous, so it's essential to check for leaks often. Since these gases are undetectable to the naked eye, a technician will use an electronic leak detector.

Flue Pipe

The flue pipe directs exhaust gases to release outside of your home to guarantee your indoor air is clean and safe to breathe. Corrosion on the metal flue pipe can result in hazardous gas leaks within the home. During maintenance, it's vital to check the flue pipe for signs of potential leaks. The furnace maintenance professional will keep an eye out for possible corrosion.

Fan and Blower

The fan or blower on your furnace moves hot air where it's needed. The low-power motor that operates the fan can run into issues, causing system malfunctions, connecting belts to slip out of place, or dirt build-up, reducing the unit's efficiency. It's crucial to have your furnace's fan and fan motor serviced during the routine check.

Combustion Air

Combustion air is the air supply that is used in the combustion process. The furnace needs a steady air supply to function. Any blockages in the intake vents or pipes can cause the furnace to stop working. These areas need regular cleaning and unclogging to ensure efficiency.

Air Filter

Filter blockages decrease the furnace’s lifespan, forcing it to work a lot harder than is normally necessary. You'll need to clean or replace your filters about once every one to three months. A clean filter makes for an efficient system, conserving energy and saving you money. One filter cleaning during an annual checkup is often insufficient — luckily, you can replace the air filter yourself, or schedule professional filter checks for each season.

Bearings and Motors

Motors and bearings are central to any mechanical system. Bearings reduce friction during operation while motors power essential elements like the fan. Your technician will ensure all furnace components are ready to perform their respective tasks. They might apply lubricating oil to smooth its operation and check that all connecting belts are securely in place.

Electrical Connections

An electrical shortage can cause furnace failure. When a fuse blows, your furnace cannot produce heat, resulting in discomfort and furthering the risk of damage due to freezing temperatures within your home. A professional will check for faulty wiring, overloaded circuits, nearby water leaks, an unclean fuse, and other possible causes of electrical failure.

Before taking any steps to maintain your furnace, make sure that you have eliminated your chances of getting electrocuted or causing gas leaks. Your unit will need to be on to inspect the flames, but for all other tasks, make sure that you turn off the power and gas to your furnace.

Before you do any actual maintenance, you should survey your furnace. Make sure you know what type of heating system you have and look up the manufacturer’s recommended safety precautions. Different systems will have different safety precautions to keep in mind. For instance, electric furnaces require a significant amount of energy to operate, but they are dependable and low-maintenance thanks to their overheating prevention features. Gas and oil furnaces tend to be cost-effective and energy-efficient, but the trade-off is that they have a higher likelihood of issues arising due to the number of components.

When you examine your heating unit, keep in mind that the surrounding area should be devoid of debris, dust, and dirt. Remove any flammable items from the vicinity, then sweep or vacuum around the outside of the furnace to ensure a safe, efficient inspection. Unless you're verifying that a specific component in the furnace is functioning as expected, make sure you power the whole thing down. After you power down the system and any circuits it connects to, check your unit for gas leaks. Gas leaks can be dangerous or even fatal, so if you notice any, immediately contact a professional to help you fix the issue.

Remember: If you aren't comfortable or capable of performing maintenance on your home’s HVAC system, you should not attempt it. You risk voiding your warranty by performing any maintenance tasks more intensive than inspection and cleaning by yourself, so always call in a trained professional to handle furnace repairs.

If your furnace has run recently, give it ample time to cool down. Once it’s safe, take a vacuum with a hose attachment and suck up any dust and dirt around the burners and base. If your hose can’t reach the far back of the burners, tape a half-inch drain line to your vacuum hose to give it a little extra length. Removing any debris near the burner ensures adequate gas flow throughout the unit.

Once you've opened the furnace, take a flashlight and examine the inside for soot buildup. This fine black powder is usually a signal of incomplete combustion, low combustion, or an inadequate airflow of toxins out of the combustion chamber. You should also lift the blower door and vacuum the blower compartment.

Removing the blower from the unit makes it easy to remove any debris the air filter might have missed. If there's a control panel blocking access to this component, loosen two of the screws and let it hang while cleaning. Use a socket and ratchet to remove the two bolts holding the blower in place and gently remove it from the unit.

After you've removed the blower, use a vacuum and a small brush to clean its blades. Be careful not to apply stress to the wiring or counterweights on the fan blades, as this could damage or break the hardware. Thoroughly remove dirt and dust from the blower with a damp cloth and vacuum to prevent the blower from becoming off balance. Along with the blades, clean any of the pulleys and belts that have accumulated debris. Make sure the fan blades are fully dry before reinstalling the component in your furnace.

The furnace's filter is supposed to keep dust and other allergens out of the heating unit. Without regular replacement, your filter will accumulate too much debris and spread the excess contaminants throughout the HVAC system and your home. Standard filters usually aren't expensive, but choosing a high-efficiency option that fits your system is a worthwhile investment if your family members have allergies or other health concerns.

Consult your owner’s manual to determine how often you should change this critical furnace component. If the filter isn’t due for replacement, you can still use a vacuum to clean out debris, and you can use a little warm, soapy water to remove stubborn contaminants. If you have a cheaper filter, change it out instead of trying to clean the thin fibers. Keeping up with air filter replacements is one of the best ways to maintain your furnace properly.

If you have a belt-driven blower, check the belts for tears and cracks to determine whether they need adjustment or replacement. A new belt only costs a few dollars, so don’t hesitate to replace a worn belt the moment you notice damage. If the belt is intact but loose, it may just need tightening to maintain safe, reliable operation.

If your furnace needs a new belt, increase the tension to run in accordance with the manufacturer's instructions. You can check the belts at any time during maintenance, but we suggest examining the felt belt while you're cleaning out the filter for expediency. If your furnace doesn't come with a belt-driven blower, skip this step.

The furnace ducts circulate hot air through your home, but time can create gaps in their airtight seal. Ducts collect dust and debris if the air filter isn't working correctly or isn’t replaced often enough. To ensure air flows freely and cleanly, you can use a high-powered vacuum to remove the debris. After cleaning the ducts, seal any leaks or gaps with high-temperature silicone or metal tape to restore efficiency.

If you have a gas furnace, resealing the ductwork also helps when performing a backdrafting test to verify that any combustion gases travel up the flue system and out of your home. To test for backdrafting, simply reconnect power to your furnace, adjust the thermostat to activate the burners, and hold a small flame next to the draft hood to ensure the smoke goes toward the hood. If the smoke isn't pulled toward the hood, combustion gases could be leaking into your home. This indicates that the flue system requires repairs to ensure proper carbon monoxide safety. 

After the backdrafting test, you should let the system cool down and then inspect the exhaust vent pipes on your water heater and furnace. If you notice any white powdery residue, you should consult a professional to replace the pipes, as this substance is a sign of corrosion. Since corrosion weakens metal parts, the exhaust vent pipes could deteriorate and leak harmful gases from the system into your home.

We know that gas furnaces and central heating systems use ductwork to blow hot air throughout your home. Along with ductwork and exhaust pipes, the vents will also require cleaning and inspection to verify they’re in good condition. Before you turn on the furnace, walk around your house and inspect each vent. Make sure these vents are accessible by removing any pet hair, scraps of paper, or other obstructions. If any of these contaminants enter the vents, they could travel throughout the ductwork and spread through the air.

Take off the registers covering your vents and use a vacuum to remove the debris. It's especially important to clean these components if you've recently renovated or completed any other home improvement projects. Once the vents are free of debris, be sure to keep furniture a safe distance away. Chairs, couches, and other heavy furnishings block airflow, which can put extra pressure and strain on your heating system.

The flame sensor is an important safety feature on your furnace. The sensor verifies whether a fire is present when the gas valve is open. If your furnace emits gas without an ignition source, the dangerous buildup of unburned gas can lead to an explosive disaster. When the burners activate, the flame sensor should shut off gas release if it does not detect a flame to keep your furnace and home safe. Regular use may cause carbon residue accumulation on the flame sensor that prevents your furnace from turning on the burner. To clean the carbon off the flame sensor, follow these steps:

1. Remove the flame sensor by pulling it out of the bracket.
2. Lightly wipe the surface with fine emery cloth.
3. Carefully wipe the metal rod with very light sandpaper to ensure it can accurately check for the presence of a flame.
4. Use a paper towel to wipe away any dust that accumulated from the sanding.

Furnace fan hardware, such as the belt, motor, and blades, needs to be inspected for signs of wear and tear. Moreover, they need to be cleaned to remove dust and debris. After the unit has been powered down for roughly 30 minutes, confirm that the furnace fan isn't overloaded by pressing the reset button. Repeat this process until the fan is functioning as expected.

Some furnaces come with a motor that will need oil lubrication to continue running efficiently. Once you’ve confirmed your motor is in good working order, you can apply a few drops of oil based on the manufacturer’s recommendations. Be careful not to over-lubricate; this could cause the oil to overflow and stain the floor.

The thermostat activates your furnace based on the temperature you input. When the unit is faulty, setting the temperature to a high level could leave the room cold and uncomfortable. This kind of issue often indicates a problem with the thermostat, especially if it’s an older model. Thermostats can stop working, so replace yours if it isn’t doing its job.

You should always check your furnace in the fall before cold weather hits, so be sure to add your thermostat to that system inspection. Thermostats don’t contain as many moving parts as a furnace, but proper thermostat care is critical for consistent performance. Other than system failure from old age, issues can arise due to improper installation, dirt buildup, and corrosion caused by loosened switches. If your decades-old thermostat finally gives out, consider upgrading to a smart thermostat for better efficiency.

Replacing Your Furnace

If your furnace is hitting the edge of the average furnace life and you’ve done all you can to troubleshoot a furnace that has stopped working, it’s time to face the facts: you need to replace your furnace.

For a high-efficiency powerhouse that can handle homes between 1000 and 1200 square feet, the 60k BTU 96% AFUE Goodman Gas Furnace is a great option. 55,000 to 60,000 BTUs, or British Thermal Units, of primary heating capacity quickly and efficiently heat your home using multi-speed functionality that conserves energy during normal operation. Setup is equally effective in upflow and left or right horizontal orientations, meaning most home layouts can benefit from this Goodman Gas Furnace.

Need something with low emissions without compromising on efficiency? The 90k BTU 96% AFUE MrCool Signature Gas Furnace is the perfect choice! Ideal for homes between 1500 and 1800 square feet, you’ll be cozy with a primary heating output of 85,000 to 90,000 BTUs. When you can have all of this power backed by an extensive warranty that includes 10 years of coverage on parts and a limited lifetime on the heat exchanger, the only thing keeping your home from consistently toasty temperatures is you!

Yearly maintenance is recommended for gas furnaces, with fall being the best time to do it.

There are certainly elements you can do yourself, but for maximum safety we recommend calling in a professional.

Maintenance for a gas furnace should include:

• Observing the burner flame and cleaning the burners
• Cleaning the blower blades, furnace filter, air ducts, furnace vents, and the flame sensor.
• Check and inspect the belts and the furnace fan
• Monitor the thermostat

Get Yourself a Furnace Today at IWAE

Eliminate the struggle to keep your home cozy during wintertime with a furnace designed specifically for your needs. Browse our wide selection of gas furnaces from major brands like Goodman and MrCool, or whittle down the pool by choosing a new, powerful system from our furnace options with an AFUE rating of 96% or higher. Figuring out the perfect furnace for your home can seem overwhelming, but you don’t have to do it alone. With the customer service experts at IWAE only a call or message away, you can breathe easy knowing someone is in your corner from start to finish.