A Beginner’s Guide to Maintenance and Repair on Your Furnace

Furnace maintenance and repair can be intimidating for DIYers and Homeowners who are unfamiliar with the process. This guide is designed to provide a step-by-step overview of the basics of furnace maintenance and repair so that you can make informed decisions about your furnace system.

Introduction to Furnace Repair

The purpose of this guide is to help DIYers and Homeowners understand the basics of furnace maintenance and repair. This guide covers the types of furnaces, assessing the condition of your furnace, beginner-friendly maintenance tips, scheduling professional maintenance, troubleshooting and repairs, identifying warning signs, and additional resources for further assistance.

It is important to note that this guide does not replace the advice of a professional. If you are unsure about anything related to your furnace system, it is always best to seek professional assistance.

Identifying Your Furnace

The first step in furnace maintenance and repair is to identify the type of furnace you have. There are two main types of furnaces: electric furnaces and natural gas furnaces.

man opening electric furnace

Electric Furnace

Electric furnaces are powered by electricity and use a heat coil and heat pump, sometimes referred to together as the “heat package”. This process of converting energy to heat is very similar to your toaster.

The heating coils are warmed to a very hot temperature, and air is blown across them and pushed out into your home. Imagine your countertop toaster, if it had a mini fan to disburse the heat. This furnace type is found most often in homes that are located in mild climates, or areas where it is difficult to transport natural gas to safely.

Gas Furnace

Natural gas furnaces use natural gas as their power source and often provide a more cost-effective heating option. These furnaces require more regular maintenance than electric furnaces because there are more steps in the heating process, and therefore more moving parts to the mechanics.

They are generally quieter than electric models but have some atmospheric dangers to keep in mind during your maintenance process. This type of system is found more often in homes that experience long or harsh cold seasons.

Once you have identified the type of furnace you have, you can assess its condition. Look for any signs of damage or wear and tear, such as cracks or corrosion in any pipes, vents, or cables. Check electrical connections for any loose wires or fraying insulation.

If you notice any signs of damage or wear, contact a professional for assistance. Rodents love the small spaces around your furnace, and will find ways to get into the casings. Be diligent in your assessment for chew marks and build-ups in places that could cause a fire.

furnace tubes

Routine Furnace Maintenance

Regular maintenance is essential for keeping your furnace in top condition. Beginner-friendly maintenance tasks are those that should be part of your seasonal cleaning and household maintenance seasonally. The most common maintenance and repair tasks include:

Cleaning or Replacing the Air Filters

This is the most frequent culprit of poorly functioning HVAC systems, and likely the easiest to handle. You can find the air filter in your furnace in most home improvement stores. More common furnace filters can even be found in general department stores, such as Kroger, Fred Meyers, and Walmart in the home improvement department.

Remove the vent panel in your furnace, and you’ll have quick access to your filter. Remove it and take a photo of the size and type you need, then replace it and head to the hardware store. When you’re there, you have all the info you need in that photo to purchase your filter.

Most filters are inexpensive, and you can often find discounts in buying more than one, and this will save you a trip to the store when you need to replace it again.

If your home has many people, or several furry family members, you may find that you need to replace your filter more frequently. However, typically, with a 1-2 inch filter, you’ll want to replace it every 2-3 months. The 3-5 inch filters can last around 3-6 months.

The largest and least common filter is 5-6 inches thick and only needs to be replaced (in ideal circumstances) every 6-9 months. If your family smokes near the furnace or has hobbies that cause more airborne impurities, you may find that your replacement period is more frequent.

Checking Electrical Connections

Even gas furnaces will have some level of electrical workings. Inside the main panel, you’ll often find an electronic motherboard or large computer chip. This portion of the furnace communicates with the thermostat and tells the furnace when to pump heat, and when to turn off.

Additionally, there may be blower fans and other aspects of the system that are controlled by electronics. Visually inspect these elements for chew marks, wear and tear from friction or heat, and other signs of damage. If they are damaged, you will need to call in a professional before it causes more severe damage.

Lubricating Motors

This isn’t a process that is accessible to all furnace owners, in some systems, the motors are in enclosed systems, and as long as there are no cracks in the casings, the lubrication is adequate.

However, in older systems, you may find that you will need to add a bit of machine oil around joints and moving parts to keep things fluid. It is important that you use the right kinds of oil, as some oils have a relatively low flash point, and can catch fire in your furnace.

Checking Safety Switches

In a gas furnace, the safety switch will turn off the furnace if something is wrong in the system. A faulty switch may cause your system to blow cold air, not turn off, or to turn on and off intermittently without a known cause. If you have a faulty switch, you should call in a service tech to replace it.

You can check the switch by removing the control panel casing, the looking for the raised red or yellow switch. Follow the electric cables at the side, and pull each cable free.

Using an altimeter, you can test the resistance in the system. If the reads are at or near 0, they are safe and functioning as needed and you can reattach the wires.

Inspecting Vents and Ducts for Blockages or Debris

Once you’ve ensured the working house of your furnace is functioning, it’s time to clean out the vents and ducts, removing blockages and debris. This is especially important if you’ve had a rodent issue anywhere in your home, and in children’s rooms.

If your heating system uses floor vents, the registers are typically removable, and you can run a vacuum hose inside to pull dust, debris, and any other detritus that has fallen into the vents. If you have a wall-mounted system that runs through the walls and floor, you can remove a vent cover and blow debris out with a leaf blower, or run a long vacuum hose through the pipes.

As you work on cleaning each section out, inspect to make sure there are no stripped bolts, broken vents, or spaces for rodents and pests to enter the system. Rats can get into space as small as the circumference of your thumb and will congregate in warm places.

Annual Professional Maintenance

In addition to regular maintenance tasks, it is also important to schedule professional maintenance at least once a year. Professional maintenance provides an opportunity for a technician to inspect your system and identify any potential issues before they become bigger problems.

They will also be able to provide helpful advice on improving the efficiency of your system.

Basic Repairs

If you encounter any issues with your furnace system, it is important to identify the problem and determine whether it can be repaired or needs to be replaced. Many of the most common repairs are easily avoided or handled during your seasonal maintenance routine.

Warning Signs to Consider

It is also important to be aware of warning signs that a repair may be necessary. Ignoring these signs could result in a fire inside the system, or inside your walls, or cause a build-up of Carbon Monoxide, which is a scentless, tasteless, lethal gas that can accumulate in your home without proper repairs and sensors.

These signs include:

  • Strange noises coming from the unit
  • Frequent cycling on and off
  • Uneven heating in different rooms
  • Higher than normal energy bills

If you notice any of these signs, contact a professional as soon as possible to assess the situation and recommend necessary repairs. The issues that cause these issues are often beyond what is safe for a DIYer to do on their own, and a professional will have a better hold on the situation and process.

Furnace FAQ


How do I know when I should replace my furnace?

The lifespan of a traditional furnace is typically 15 years or so, depending on the regularity of maintenance and repair. If you’re coming up on the end of your furnace’s lifespan, begin saving for the HVAC replacement costs (which vary from company to company).

Replacing your furnace is a job to be done by professionals only, as it involved a lot of potentially dangerous components.

What is the most common furnace issue that can cause poor function?

Clogged air filters. Many homeowners, and most commonly home renters, take their furnaces for granted and assume it will just keep chugging away. However, the air filter is the first form of defense for your furnace against debris and other things that cause it to work harder.

When the furnace has to blow harder to move the heat, it costs you more in heating bills, and creates a fire hazard.

How do I relight my pilot light or discover the cause of ignition problems?

If you have a natural gas furnace, and it is an older model, you’ll be able to take the panel off and see where the pilot light burns, this tiny flame should always be on, unless your system has an electric ignition.

If it is not burning, and you don’t have the electric spark start type system, you can relight your pilot light using a long match, or a long BBQ lighter. Ensure that you don’t smell excess natural gas before you light it.

If you have concerns about the safety of lighting the pilot, calling in a tech is never a bad thing. They may even be able to determine what caused it to go out.

How often should I schedule professional maintenance?

It is recommended that you schedule professional maintenance at least once a year. This will help ensure that your furnace system is running efficiently and identify any potential issues before they become bigger problems.

Is it safe to make furnace repairs myself?

If you are unsure about anything related to your furnace system it is always best to seek professional assistance. Attempting repairs yourself could result in further damage or injury if not done correctly.

However, basic maintenance doesn’t take much in the way of professional knowledge or skill. Primarily, your job is to keep the area clean and free of debris and keep a mindful eye on all cables and pipes for chewing or other damage.

What should I do if I notice warning signs that my furnace needs repairs?

If you notice any warning signs that your furnace needs repairs, contact a professional immediately for assistance. They will be able to assess the situation and recommend necessary repairs.

Additional Safety Notes

Always keep the space around your furnace paneling clear of things that could block you from accessing it. Never stack furniture or stored goods in front of the furnace access panel.

Keep dirt, debris, and rodents out of any part of your furnace that is exposed to heat or flame. Most importantly for gas furnace owners, keep your CO2 sensors on, and stocked with fresh batteries.

These little devices should be located on each level of the home to monitor CO2 levels and help save you and your family from injury or death.

Resources for Further Assistance

If you need further assistance with understanding the basics of furnace maintenance and repair, there are several resources available online. Video tutorials provide an easy way to learn more about your system and how to perform common maintenance tasks such as cleaning filters or checking electrical connections.

Manuals can also provide helpful information on how to identify common problems and how to make certain repairs yourself if you feel comfortable doing so.

When looking for a professional in your area to service or repair your furnace system, be sure to look at reviews, time in the business, and certifications. Ensure they are licensed, bonded, and insured in your state, and that they carry a good reputation.

Your furnace is one of the few systems that we depend on greatly while knowing very little about. It’s easy to take for granted until the moment it’s no longer working.