What’s a Furnace Tune-Up?

Heating system maintenance is very important for keeping your system in tip-top shape. Annual maintenance is a great thing to do and it is not something you should forget about. But you’re likely wondering what a Furnace tune-up is. In this blog post, we’ll be discussing what it is and what to expect from it.

HVAC technicians come equipped with everything they need to get your system up and running and ensuring that your system is working correctly.

Types of HVAC Systems

Furnace Systems

There are several types of HVAC systems and each one determines how it receives a tune-up. Furnaces are the most common form of heating systems and often the most serviced. How a furnace works is pretty simple, it blows hot air through a duct in the house that will often transfer heat throughout the home.

Forced Hot Air

Another form of heating system uses “Forced Hot Air”. These systems will often work together with a compressor and cooling coils. They will provide heat during the cold winter months, but also provide cold air in the hot summer months.


Many homes nowadays will often use boilers to transport hot water throughout your home which will come out through baseboards in your home. The hot water will then come out through the baseboard radiators in your home. While the tune-up process is similar for both boilers and furnaces, boilers do not have air filters like a furnace does.

This is what an oil-fired furnace will often look like. They are used to send heat throughout your home and keep it warm.
Air ducts are often used to transfer both heat and cold air throughout your home depending on the time of year. They do this to both heat and cool the home.
If your home has baseboard heating, they will often look like this. This also means that your home will usually use a boiler to heat your home and transfer hot water throughout the home.

The Steps of a Tune-Up

The process of a heating system tune-up is similar to servicing your car. Like checking the fluid levels and filters on your car, an HVAC technician will do this for your furnace. The technician will often inspect, clean, and replace the following items if needed.

Checking Your Oil Supply Line: Your HVAC technician will check for incoming oil from your heating oil tank. They will usually disconnect the line to ensure that the burner is getting good oil flow from the tank. Sometimes there is some resistance in the line. This is usually due to a build-up of sludge. Usually, if this is the case, the line will need cleaning by pressurizing it from one end to the other. Alternatively, you can drain the other end of the line by hard-pumping the oil out of it.

The HVAC technician will normally disconnect the supply line from the filter to ensure that enough flow and oil are reaching the tank. If there’s a build-up of sludge, the technician will carefully and slowly use some pressure or a bit of suction to remove sludge from the line.

Changing the Oil Filter/Cleaning or Replacing the Strainer: The oil filter in your tank can get quite disgusting over time. In this instance, the technician will take out and replace the filter. He will also inspect, clean, and replace the system’s strainer if it needs it. The strainer will usually act as a second filter inside the system. It will catch anything that makes it past the oil filter.

This image shows how important it is to regularly change your oil filter. Over time, the filter can build up an incredible amount of sludge. To prevent the system from getting overfilled with sludge, it’s a good idea to clean it out every so often.
This is the strainer for your standard heating oil system. It will catch anything that the filter will not be able to catch. The strainer will also need to be replaced as needed.

Inspect, Replace, or Adjust the Components of the Burner: Before the combustion process, heating oil must go through a nozzle to become automatized. However, the nozzle can clog and wear out over time. But, the technician can replace it during the tune-up. After he replaces the nozzle, the HVAC technician will use a special template to match up the tips of the nozzle with the tips of the electrodes, as shown in the below photograph. The electrodes will then ignite the automatized fuel. If these electrodes show any wear and tear, the technician will promptly replace them. Finally, the technician will do a visual inspection of the system’s combustion chamber to ensure everything is working smoothly.

During the tune-up process, the technician will replace the nozzle and adjust the electrode as shown above. If the electrodes are too worn out to line up with their template, then the technician will need to replace them.

Check and Clean the Heat Exchanger. The cool air in your house will pass through the heat exchanger before going through a conversion process. That process turns it into hot air. Over time older furnaces will tend to fail, and this is often because of cracks in the heat exchanger. These cracks allow the burner’s exhaust to mix in with the clean air that is making its way into your home. Before they become a problem, the HVAC technician will be sure to take a careful look to find these issues and fix them.

This is a close-up view of the heat exchanger and shows what the technician will need to examine for any possible damage.

Perform a Combustion Analysis: There’s a special tool that the technician will use to measure the efficiency of your system. He’ll use it to perform a pump test that’ll help check the color of smoke to ensure that it’s adequate. Finally, the analyzer will check both the temperature and CO2 content. It will then use that information to effectively calculate the system’s efficiency.

The technician will use this analyzer to measure the CO2 content and temperature of your exhaust gases.

Change The Air Filters: The easiest part of your heating system tune-up is changing out your air filters. You can do this once per year yourself. However, it’s not a problem if you wait for your HVAC technician to replace them during your annual tune-up. Replacing the filters doesn’t require you to use any tools and they are very easy to replace! We go over how to replace them in this post here.

The Peace of Mind of a Furnace Tune-Up

As we continue to make our way through the cold months of the year, it’s good to be confident in your heating system to keep you nice and warm through this time of the year.

Having annual preventative maintenance on your HVAC system will ensure that your system is still running as efficiently as possible. Like changing the oil on your car, changing your system’s oil filter and worn-out items on your furnace should be done regularly. Just be sure to hire a qualified, licensed, experienced, and insured technician to do this for you.

Happy Heating,