Can You Run Your Furnace Without A Filter?

So, do you need a furnace filter for your HVAC unit? A furnace filter doesn’t just purify your air, it keeps the inner mechanisms of your HVAC system functioning properly.

If you run a furnace without a filter, it won’t cause immediate problems, but contaminants will build inside your heating unit and can cause long-term damage. Keeping a clean filter ensures it operates efficiently and can keep dirt, dander, and debris from circulating back through your home.

A furnace filter is critical to keep your indoor air quality pristine and maximize the lifespan of your furnace. These filters are easy to change, making this a quick, painless home maintenance task that drastically improves furnace airflow.

Importance of a Furnace Filter

The air in your home is first sucked into the furnace through a blower fan. Next, air passes through the air filter before it’s heated and recirculated back into your home. The filter consists of tightly woven fiberglass, paper, or cloth elements. This creates a semipermeable blockade that traps harmful particles. 

A clogged air filter prevents air from flowing through the system which can lead to:

  • Cold indoor temperatures even with the heat turned on
  • Poor airflow
  • Expensive utility bills
  • Worn-down HVAC system
  • Overheated furnace

Is it Bad to Run a Furnace Without a Filter?

So what happens if you don’t have a filter in your furnace? The answer to that is pretty straightforward: yes, you can, but you’ll most likely damage your unit if you do. If you’re wondering, “Do you need a furnace filter?” then just keep in mind that running a furnace without a filter temporarily, such as for one night, won’t affect your HVAC system detrimentally.

However, the longer you run your heating system without an air filter, the more contaminants accumulate inside your heating unit’s inner mechanisms.

The two main reasons you shouldn’t run a furnace without a filter are that your furnace could break down suddenly and that air will be filled with contaminants that are unsafe to breathe in. If your heater goes out in the middle of winter due to a clogged air filter, call the HVAC professionals at John C. Flood immediately.

Risks of Running Your Furnace Without a Filter

The purpose of a furnace air filter is to keep your HVAC system in pristine condition, especially the blower motor and evaporator coils. If you choose to run the furnace without a filter installed, several potential problems can arise and lead to the breakdown of your heating system.

Poor Air Quality

The most prevalent issue that stems from running a furnace without a filter is poor indoor air quality. Dust is stirred in a home when the furnace continually cycles the air. Debris is sucked back up through the intake, pumped back through the air vents, and remains suspended in the air until it is inhaled or accumulates within the HVAC unit.

Contaminated Ductwork

Without a filter, pollutants and air toxins will travel throughout the ductwork. The debris will accumulate inside the ductwork, becoming trapped by the ribbed aluminum tubes. This accumulation will harbor moisture within the ductwork, creating the ideal conditions for mold to grow. Mold spores will begin to circulate throughout your home whenever the HVAC system is running and be extremely dangerous to occupants within the household.

What Happens if you use a Dirty Filter?

So we’ve answered the question, “Can you run a furnace without a filter,” but what about running a furnace on a dirty filter? What will happen then?

Similar to running a furnace without a filter, running your furnace on a dirty filter won’t hurt it for a day or two, but it can have hugely negative effects over the course of time. The furnace filter performs integral duties in your furnace system, and when it’s clogged with air contaminants, dust, and other debris, it prevents air from circulating properly. That means your furnace system will need to work even harder for the air to circulate, stressing the system and collecting even more contaminants in the unit’s mechanisms.

Essentially, a dirty filter will restrict airflow and make your heating system work harder, which increases your utility bill and potentially damages your unit. A furnace that is overworked can easily overheat and break down, so inserting a clean, new air filter regularly will help protect the integrity of your unit. An air filter will keep contaminants out of your furnace, helping it run easier and smoother, extending your furnace’s lifespan and keeping your energy bill at a reasonable place.

How Often Should You Replace a Furnace Air Filter?

Check your HVAC filter once a month to ensure it’s not clogged, especially during the heavy-use winter months. Whenever the filter appears dirty, it’s important to replace it. At a minimum, change the filter every three months to improve heating efficiency.

How often to replace furnace filters depends on the size of the home. A clean filter will also prevent dust and dirt from building up in the system which can lead to expensive maintenance and your system breaking down prematurely. If your furnace is not blowing hot air, it’s important to check the air filter.

How To Change Your Furnace Filter

1. Locate your filter

Shut off your furnace to be safe before opening up your furnace. The furnace filter is either inside the furnace itself or inside the return air vent. Remove the service panel to view the filter. Check the furnace manual if you cannot locate the filter.

2. Identify the replacement filter type

Disposable filters usually have a flimsy cardboard frame, whereas filters with a plastic frame are typically reusable. The frame of the old filter should display the size, which can vary depending on the unit size and model. Reference your furnace manual to determine what type, size, and thickness of the filter you need for your home’s furnace.

3. Remove the old filter

If you have a new filter, throw away your disposable filter and replace it. If your filter is reusable, wash it off and replace it. Your old filter should have arrows noting what direction the air flows. This is to help you insert the new filter the same way.

4. Secure the new filter in place

Remove packaging from the new filter so the air can flow through. Slide the filter into place, ensuring the arrows on the frame point the same direction as the previous filter. Close the service panel and turn the furnace on.

Contact John C. Flood to Breathe Better and Stay Warm

If you choose to run a furnace without a filter, you leave your heating system susceptible to dirt and debris that will inevitably lead to expensive repairs and a premature death of your HVAC system.

It’s important to understand what heating system is best for your home in order to pick the best furnace air filter. Whether you want to know how much a furnace inspection costs or get your furnace filter replaced, contact John C. Flood for the best value and highest quality heating system maintenance.

Trust your home to the John C. Flood team to ensure your air quality is top-notch. Our HVAC professionals will take care of all your furnace filter maintenance. HVAC systems are complex and require routine inspections and annual maintenance. Call (703) 214-5611 or Schedule your HVAC inspection today!

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