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How to Maintain An Oil Furnace Heater in Big Bear, CA

Bear Valley Plumbing & Heating


On paper, your furnace should last for up to ten years. In reality, it can go in for 15 to 25 years depending on the usage level. This lifespan and the ruggedness you expect to come with your unit make it easy to forget maintenance.

Therefore, in this article, we show you the steps involved in maintaining your oil furnace. We also highlight the telltale signs of a hitch. We must emphasize that periodic cleaning is the best maintenance for your oil furnace. Read on to learn more.

Signs Your Oil Furnace May Need Maintenance

Before learning how to maintain your oil furnace, it is important you know the signs of a likely issue. Below, we explore just that.


It is natural for your furnace to make sounds. However, these sounds should not be irregular or unusually loud. If you hear rattles or vibrations within your unit, you may need to schedule a maintenance check.


You need to maintain your furnace when soot begins to appear on the outside. The presence of black soot might indicate issues with the burning of fuel.

Additionally, check your chimney for smoke. The emission of black smoke could mean that the oil is not properly burned.

How to Maintain Your Oil Furnace in 7 Steps

To maintain your oil furnace yourself, you need to have a checklist.

  • Turn off the power on your oil furnace
  • Clear the unit of soot and any other dirt
  • Examine the flue pipe
  • Change the oil filter
  • Replace the air filter
  • Adjust burner and test for efficiency
  • Do a cleaning of the floor vents

Each process is explained below:

Step 1: Turn Off the Power on Your Oil Furnace

This is a safety measure. Shutting off the power means you can maintain your furnace while protecting yourself and your family. For you to stop the system, simply flip the switch to ‘off.’

The power switch is often located at the top of the stairs in your cellar or next to the burner. Its distinct red color makes it an easy component to find. Also, you can stop the fuel inflow using the shutoff valve near the oil tank. The valve is equally easy to identify and operate.

Step 2: Clear the Unit of Soot and Other Dirt

Cleaning the dirt from your furnace’s combustion chamber can indeed take some time. However, it is a highly fulfilling task. When you remove debris such as water vapor, soot, carbon monoxide, and any other surrounding dirt, you enjoy smooth functionality for a long period.

Your combustion chamber guarantees the release of gases from the burning process through a flue pipe for better understanding. Its walls also secure your home from the gas the burner emits.

A cleanup of the combustion chamber helps to remove debris that has collected on the chamber’s walls. When left unattended, the dirt can result in corrosion, which damages the structure.

To clean the chamber, you can procure a wire brush to clear any material on the wall. However, you will need an industrial shop vacuum to get a thorough cleaning job.

It is important that you examine the chamber for any holes or cracks. The presence of these may require you to replace the entire chamber for a hitch-free operation.

Step 3: Examine the Flue Pipe

As stated earlier, the flue pipe channels gas produced during combustion from your home. Examining it means that you try to spot holes, cracks, and other leaks for quick maintenance.

When checking the pipe, pay close attention to where it joins with the furnace. If you discover small holes in the structure, you may be able to fix them in the short term with foil tapes. However, when the damage is extensive, you might need a complete replacement of the pipe or furnace.

Also, keep an eye out for the barometric damper. This component serves to control the draft in the furnace. You will find the damper on a furnace with a Category I vent and a lower than 83% annual fuel utilization efficiency. Often, the barometric damper will be found in the flue vent connector between the chimney and the furnace. With the adjustable weight of its round door, you can work the damper to ensure your furnace runs without issues.

You can do this by adjusting the weights and scale on the barometric damper. For the appropriate number to follow, consult the manufacturer’s guide. There you will find instructions on maintaining a steady temperature using this device.

Adjusting the barometric damper helps you to conserve fuel and reduce energy loss. A call to your manufacturer will provide further guidance if you are uncertain on how to implement it.

Step 4: Change the Oil Filter

The filter prevents clogs in the furnace’s oil-burner nozzle. When debris finds its way into the nozzle, the furnace may malfunction and shut down. Fortunately, you can replace your filter in a matter of minutes. This is something you should do a minimum of two times in every heating season.

Because the oil filter purifies fuel before it enters the furnace, you will find it close to the system itself. To replace it, shut the oil valve and remove the old filter. Attach this appropriately and dispose of the old one.

Step 5: Replace the Air Filter

Like the oil filter, replacing the air filter is easy as well. It is important to ensure that you have the right fit for your furnace as no air filters are the same.

To make a replacement, you will find the air filter either in the furnace or the furnace’s return air vent. Check for an arrow that indicates where the air flows. Determining this helps you to install your filter in the correct direction. You can note the path with a permanent marker of your own to identify it quickly.

Remove the old component and install the new air filter. Make sure you note the date you replaced it. Normally, you should change your air filter every three months or less, depending on your home size and whether you have pets.

Step 6: Adjust Burner and Test for Efficiency

Testing your burner’s efficiency requires you to measure the gases in the flue pipe and derive its efficiency. This process, called combustion analysis, helps you increase your furnace’s efficiency while ensuring it functions safely. You will need to measure the concentration of gases in the flue pipe, the temperature, the furnace’s soot level, and its draft pressure.

To begin, extract a gas sample from the flue using a probe. You can then measure this with a thermocouple to know the highest temperature of exhaust gas. You can also determine the differential pressure between inner and outer parts of your system’s flue, measure draft, and calculate soot, all based on a sample from the flue.

After the analysis, you are equipped with various data to understand your furnace’s safety and efficiency. You can utilize these data to determine excess air and efficiency in the combustion cycle.

When doing analysis, a combustion analyzer can help with collating measurements. This electronic tool enables you to take samples from a flue using a vacuum pump and examine this sample with electrochemical sensors.

Step 7: Do a Cleaning of the Floor Vents

This final part may seem a bit intense. It is, however, important to understand that removing dirt from the floor vent will keep your furnace running at an optimal level.

A short period of cleaning can ensure you have a more efficient furnace and better air quality.

Why You Should Maintain Your Oil Furnace

Oil furnace maintenance should occur at least once a year. Below, we explain a few benefits of maintaining your oil furnace.

Saves Money

Periodic maintenance saves you the costs of extensive repair or buying a new furnace. Through routine fixes like replacing a filter, you spot problems long before they develop into major technical issues.

Makes It Safer to Operate

A crucial part of an oil furnace’s work is combustion. A poorly maintained unit can result in a collection of fuel, which can, in turn, ignite explosively. Maintaining your oil furnace, therefore, helps to keep your property safe.

Increases the Service Life

When you maintain your furnace frequently, you can increase the period of use.  Additionally, spending time and energy on annual maintenance projects saves you the higher cost of purchasing a new one.

Protects Air Quality

Similarly, maintaining your oil furnace protects the quality of your indoor air. With clean emissions, you can rest assured of a healthy living environment.

Hire a Professional in Big Bear, CA

Doing your oil furnace maintenance yourself for the first time can be tricky. If you feel uncertain about the steps, you may want to employ a professional technician. This prevents the problems from compounding and creating even higher costs.

To determine which maintenance service is best for you, you can check online reviews of the service. You can also investigate the company’s licenses and its technical competencies.

In addition to this, while you can maintain your oil furnace at any time, there are seasons when it is easier to do. These include fall, before the cold season, and spring, after it has ended. During the season itself, HVAC services are often engaged in other repair needs.

Bear Valley is a Call Away!

In the sections above, we have explained how to maintain your oil furnace, signs that your furnace needs maintenance, the benefits of maintaining your furnace, and when to hire a professional. You can include cleaning your oil furnace in your routine cleaning activities to achieve consistency.

For efficient HVAC technicians, you can reach out to Bear Valley experts for customer-focused and high-quality services at all times. Place a call to schedule a free case evaluation!

If you are looking for a Big Bear plumbing, heating & air conditioning contractor, please call (909) 584-4376 or complete our online request form.