Running a Furnace Without a Filter: Is it a Good Idea?

September 21, 2023

While running a furnace without a filter may not seem like a big deal, neglecting to use an air filter or failing to replace it regularly, you risk damaging your furnace. 

What happens if there is no filter in the furnace is that contaminants accumulate inside the unit, which can result in extensive furnace damage and poor air quality. These contaminants, such as debris, dander, and dirt, can exacerbate allergies. 

By using a filter, you’re helping ensure that your heating equipment functions optimally and lasts longer and treating yourself and your loved ones to cleaner, fresher air.

Read our detailed guide to what happens if there is no filter in the furnace and the steps you can take to maintain it for a more hygienic and healthier living environment.

What Are the Consequences of Operating an Unfiltered Furnace?

How long can you run a furnace without a filter? You can run the furnace without installing a filter, but only temporarily (such as overnight, awaiting a new filter). If you let it run for very long without filtration, contaminants will build up. 

The dangers of running a furnace without a filter for an extended period can lead to serious problems. Here’s what happens if there is no filter in the furnace:

1. Poor Indoor Air Quality

Indoor Air Quality (IAQ) plummets when there is no filtration. Your family may experience health problems as contaminants and dust move through the ductwork into the home. Mold spores could proliferate in the ducts, causing breathing issues and sleep problems. Without an HVAC filter, poor indoor air quality can pose real health risks to you and your family, and you should take these risks seriously. 

2. System Damage

Filters act as a barrier that prevents dirt and debris from reaching critical furnace components. Without a filter, buildup accumulates on blower fans, coils, and motors, reducing lifespan and increasing the likelihood of breakdowns. 

Clogged furnace components caused by a lack of a filter can cause your furnace to overheat, suffer from motor failure, or experience system malfunctions. Not only can your furnace suffer, but your entire HVAC system may stop working. Regularly replacing the filter is a simple, cost-effective way to prevent expensive repairs.

3. Decreased Energy Efficiency

When dust and debris clog HVAC components, your system must work harder to circulate air, leading to higher energy consumption. This can increase your utility bills and put unnecessary stress on your furnace. 

4. Uneven Temperature Distribution

A clogged or missing filter disrupts the balance of airflow in your HVAC system, leading to inconsistent heating throughout your home. Some rooms may feel too warm, while others remain chilly. Without proper airflow regulation, the furnace struggles to disperse heat evenly, making your home less comfortable and forcing the system to work harder than necessary.

If you’ve been running your furnace without a filter for an extended period of time, we recommend a professional inspection ASAP. Call Brothers at 704-620-6252!

The Role of a Furnace Filter and Why It Matters

A furnace filter is a device made from cloth, paper, or fiberglass that traps contaminants so they don’t circulate through your home and harm your health. 

The purpose of a furnace filter is to prevent unfavorable particles—dust, pet hair, pollen, allergens, and debris—from contaminating your living area and worsening your indoor air quality.

Maintaining proper airflow will also reduce the strain on your HVAC system and improve its efficiency. Regular filter replacement will help protect your furnace, improve your home’s air quality, and save money on energy bills and repairs. 

Need a furnace tune-up or want to save on repairs or installations? Check out the specials at Brothers.

The Impact of Running Your Furnace with a Dirty or Clogged Filter

While installing a furnace filter is a good first step, you’ll also want to make sure you’re scheduling regular replacement reminders. A dirty filter can be just as harmful as no filter at all. 

When a filter becomes clogged with pollution, airflow can become restricted, causing the furnace to labor excessively to maintain the home’s basic heat level. Under such inefficient conditions, you can expect your power bill to rise. Working harder than necessary can make the furnace overheat or malfunction.

Brothers offers a Pro Service Plan that will keep your HVAC system in shape all year long. The plan includes great discounts and two maintenance visits per year! 

Furnace Care: How Often Should Furnace Filters Be Replaced?

Although the frequency can depend on your filter type and climate, ideally, you should change the filter every one to three months. In winter, air filter replacement is a task you don’t want to ignore on your to-do list, since you’ll be running the furnace more often and spending more time inside. When a filter appears dirty, it’s time to install a new one. 

While “every 90 days” is a good general guideline, below are some more specific scheduling recommendations:

Filter Type

• 1-inch filters: Change every 1-3 months

• 4-inch filters: Change every 3-6 months

• 5 to 6-inch filters: Change every 9-12 months

Home and Climate Type

• Dusty or dry climate: Change every month

• Homes with pets: Change every two months

• Homes with multiple pets or people with allergies: Change every 20-45 days

• Vacation homes or vacant homes: Change every 9-12 months 

When you don’t replace your filters on time, airflow is restricted, which can add strain to your system. To prevent this, regular replacement using our guidelines above is important.

The professionals at Brothers can help you with furnace maintenance, including replacing your filter. Schedule an appointment with us today.  

Signs That It’s Time to Change Your Filter

How do you know when it’s time for a new filter? Here are some key signs to watch for:

• Increased dust and allergies: If you notice more dust collecting on surfaces or an increase in allergy symptoms, your filter may be clogged and no longer effectively trapping airborne particles.

• Reduced airflow: A clogged filter restricts airflow, making it harder for your furnace to circulate warm air. If some rooms feel cooler than others or your system seems to be struggling, check the filter.

• Higher energy bills: A dirty filter forces your HVAC system to work harder, increasing energy consumption. Your filter might be to blame if your utility bills have spiked without explanation.

• Unusual odors: Musty or burning smells when the furnace is running can indicate a dirty or clogged filter that needs to be replaced.

• Visible dirt and debris: If your filter looks dark, dusty, or clogged with debris, it’s time for a change. A clean filter should allow light to pass through it.

If you’re still unsure when to replace your filter (or even where it is), give Brothers a call at 704-620-6252. 

Choosing the Right Furnace Filter

Now that you know you shouldn’t be running a furnace without filter protection, let’s detail how to find the right filter for your home. When shopping for a filter, here are a few things to keep in mind:

• Filter size: Check your furnace manual or the filter you’re currently using for the correct dimensions. The correct filter size is important to keep your system working properly.

• Filter type: There are a few different materials to choose from, like fiberglass, pleated, electrostatic, and HEPA filters. Fiberglass filters are affordable but may need to be replaced more often, while pleated and electrostatic filters offer better air quality. HEPA filters are the best at trapping tiny particles, but they can be a bit pricier, and aren’t recommended for many home HVAC systems because of restricted airflow. Make sure to check with your manufacturer.

• MERV rating: The Minimum Efficiency Reporting Value (MERV) rating shows how effective the filter is at trapping particles. For most homes, a filter with a MERV rating between 8 and 13 will do the trick, balancing efficient filtration with good airflow. 

• Household needs: If you have pets, allergies, or any respiratory concerns, go for a higher-rated MERV filter or a HEPA one, if your system allows for it. A better filter will capture more allergens, dust, and pet dander.

Brothers can also help you find the best filter for your home. Call us today at 704-620-6252 or schedule an appointment—it’s that easy!

How Do I Change My Furnace’s Filter?

It’s relatively easy to change your home’s furnace filter. Here are the steps to take:

Step 1: Find the filter

Switch off the furnace’s power. Locate the filter in the return air vent or inside the furnace. If you can’t remember, check the furnace manufacturer’s instructions. 

Pro tip: Take a photo of the filter and how it’s placed in your unit, so you’ll have a visual reminder of the type of filter you need and how it should be installed.

Step 2: Determine if it’s reusable or replaceable

Disposable filters have cardboard frames, while reusable air filters have plastic frames.

Step 3: Verify the thickness and size of the filter

You need to match it precisely, so look at the filter instructions if you’re unsure about the dimensions for replacement.

Step 4: Take out the dirty filter

Throw out the filter if it’s meant for single use, and then put in a replacement filter. For a reusable filter, wash it per the manufacturer’s instructions before reinstalling it into the furnace.

Step 5: Check the orientation

Check that the filter is lined up so the air will flow in the correct direction. Typically, arrows are printed on the filter’s frame to guide you during installation. After placing the filter, close the panel.

Now, you can resume running the furnace, confident that the fresh filter will help eliminate contaminants and dust, improving indoor air quality. The furnace will run more efficiently, cost less to operate, and work longer than if you failed to clean or swap out the filter regularly.

If you have questions about your filter or need furnace service, call the professionals at Brothers Heating & Air in North Carolina and South Carolina at 704-620-6252 and we’ll take care of you

Is it Time to Call for HVAC Maintenance? Brothers Is Here!

Brothers Heating & Air are your trusted HVAC professionals. You can depend on us to look after your home’s furnace. We are standing by for all of your heating service needs, including filter replacements, ongoing maintenance, new furnace installation, furnace repairs, or even replacing your heat pump. 

Brothers Heating & Air hires certified, highly trained HVAC experts who follow industry best practices and use the latest equipment to do our work as efficiently as possible. Our team will help keep your home nice and warm during winter, even as the mercury plummets.

We’re proud of the reputation we’ve earned for being a furnace repair company that North and South Carolina homeowners can trust.

Call us to arrange service today if your furnace is on the fritz! We’ll diagnose the problem and provide a customized plan to repair or replace the system, so your family will stay comfortable and safe. Call us today at 704-620-6252 to learn more or schedule service!