How to Check Furnace Filter: Expert Tips and Tricks!

Rima Chatterjee

A furnace filter is essential for your HVAC system. It traps airborne particles, like dust, pollen, and pet dander. Over time, the filter gets dirty. This affects the performance of your HVAC equipment. Here are the steps to check your furnace filter and know if it needs changing.

  1. Turn off the AC unit or heating system.
  2. Locate the blower compartment door. It’s usually near the base of the furnace or air handler.
  3. Open the door. Carefully take out the old filter. Note which way it was installed.
  4. Check the filter. Is it dirty or clogged? If yes, it needs to be changed.

The frequency of changing filters varies. It depends on the home size, type of filter used, number of pets, allergies, etc. A general rule is to change them every 1-3 months.

When purchasing a new filter, make sure it fits properly. Check the size. Furnace filters come in various MERV ratings. This shows their filtering capacity. Consider your needs when buying a new one.

Put the new filter in the same way you took out the old one. Follow any arrows printed on its frame. After reinserting the filter and closing the compartment door, turn back on the HVAC system!

My friend John learned the hard way. He only changed his furnace filters every year. His furnace struggled to run. The air filter was clogged with dirt and debris. By regularly changing his filters, his equipment ran more smoothly. His home had better indoor air quality! So, don’t forget to change your filter. Otherwise, you’ll be breathing a dust bunny army!

how to check furnace filter

Importance of checking furnace filter

Checking your furnace filter regularly is an absolute must for a working HVAC system. A clogged filter can reduce airflow, weaken heating and cooling efficiency, and even harm equipment. Here are 6 reasons why it’s essential to check the filter:

  • Better Air Quality: Traps particles such as dust, pollen, pet dander, mold, and mildew.
  • More Efficient: Clean filters guarantee better airflow, which boosts HVAC system efficiency and reduces energy costs.
  • Extended Equipment Life: Dirty filters may cause blower motor problems or another type of heating system issues, leading to early replacements.
  • Pets and Allergies: Replacing air filters helps people who suffer from allergies or asthma by taking out airborne irritants from pets or pollens.
  • Decreased Maintenance Costs: Taking care of a small maintenance project like replacing an air filter is much cheaper than paying for expensive repairs that could’ve been prevented.
  • Keeping Warranties: Consistent maintenance shows you’ve cared for appliances when filing any warranty claims.

It’s important to note different filters serve different purposes, depending on their material type or MERV ratings. Also, make sure to follow the manufacturer’s instructions when putting new filters in-home AC units.

Remember to check your filter each month during seasons with more HVAC usage (winter/summer). When checking, the airflow arrows should face the ductwork. Get a washable filter for less landfill waste! It offers quick protection from dust contaminants with reusable cardboard frames; check if it fits before buying.

Got it? Then let’s play – ‘Who Wants to Breathe Clean Air?’

How to Check and Change Furnace Filter

To check and change your furnace filter, follow a step-by-step guide with sub-sections including how to locate the furnace filter, determine the filter type, check the MERV rating, turn off power to the furnace, remove the old filter, inspect the filter for dirt, replace the filter with a new one, checking the air handler and blower motor. Lastly, reinstall the access door to ensure the furnace filter change is complete.

Step-by-Step Guide

Maintaining a filter for your furnace is essential for fresh air and lower energy bills. Here’s a guide on how to check and change it:

  1. Find Location: Find the spot where air enters your furnace, near the thermostat or return vent.
  2. Turn Off the Furnace: Before doing anything, turn off the heating system from the electrical panel.
  3. Remove Old Filter: Slide the old filter out with care to avoid spreading dust.
  4. Check Condition: See if there’s dirt, debris, or discoloration on both sides.
  5. Install New Filter: Put the new filter in with arrows pointing toward the blower motor.
  6. Turn On & Test: Close everything up, turn on the furnace, and enjoy your improved air!

Changing filters every 1-3 months is not just cost-effective but also extends system life. Dirty filters can damage components and mess with indoor temp, so take action now!

Locate the Furnace Filter

Locating the furnace filter is key for a healthy and clean atmosphere indoors. It captures dust, molds, and bacteria that can affect your well-being. Here’s a four-step guide to finding your filter:

  1. Turn off the furnace – This is for safety reasons. You don’t want to touch hot surfaces.
  2. Find the air duct – The filter is usually between or at the air ducts.
  3. Open the access panel – After finding the air duct, unscrew or unlatch it.
  4. Remove the filter – In the exposed panel, you’ll find a filter.

It’s essential to know the size of your air duct before replacing the filter. Get advice from HVAC professionals or manufacturers.

Checking your air filters is important. Dirty ones can block airflow, making motors, springs, and fittings wear out faster. Change your filters every three months. If you have pets or high pollen levels, you may need to switch more often. Look into electrostatic filters or HEPA filters for better performance.

To sum up, locating a furnace filter takes a few minutes but has a big effect. It reduces allergens, helps you breathe easier, extends the life of your HVAC equipment, and saves energy. Consult an expert if you’re unsure about how to find or change your air filter. 

Finding the perfect furnace filter is like finding the one – make sure it fits and won’t cause problems.

Determine the Filter Type

Figuring out the filter type is a key part of keeping your furnace efficient! There are three main filter types: disposable fiberglass filters, pleated filters, and electrostatic filters.

  • Disposable fiberglass filters are basic and low-cost, made of spun glass. They capture large particles such as dust and lint.
  • Pleated filters are made of polyester or cotton paper blend, folded accordion style. They trap smaller particles such as pollen and pet dander.
  • Electrostatic filters are usually made of metal mesh or paper fibers with a special electrostatic charge. They can catch even the smallest pollutants, so they are great for allergy sufferers.

Remember to check the size and type of filter for your furnace before you buy a replacement. Additionally, investing in high-efficiency filters can boost air quality in your home.

Merv ratings are a way to compare filters – not all are equal, just like not all exes are worth keeping around!

Checking the MERV Rating

It’s essential to frequently check and change your furnace filter. An important part of this process is checking the MERV rating. A higher rating doesn’t always mean better filtration. Respect your furnace’s manufacturer’s recommendations for suitable MERV ratings. Purchase multiple filters at once, so you always have a replacement ready. Finally, turn off the power and give your furnace the cold shoulder.

Turn off Power to the Furnace

When it comes to changing or checking your furnace filter, safety is key. Follow this 3-step guide for turning off the power:

  1. Find the breaker panel and switch off the circuit that powers your furnace.
  2. If there’s no label, refer to the owner’s manual or call in a pro for help.
  3. Test the furnace to make sure it doesn’t generate heat or air.

Remember, furnaces can have multiple breakers. So switch off every one connected to your furnace before you start.

For extra safety, wait about 30 minutes before approaching the furnace after you’ve completely turned it off. Doing this will help make sure any residual charge in the system has gone away. Taking these precautions will keep you safe while also avoiding damage or accidents during repair or replacement work.

Time for a fresh start – bid farewell to your old filter!

Removing the Old Filter

Replace that furnace filter and stay warm! Here’s the process:

  1. Locate the filter compartment – usually inside a furnace cabinet or behind a grate.
  2. Turn off the power supply to prevent accidents or shock.
  3. Take off the removable cover with either latches or screws.
  4. Gently slide out the old filter and dispose of it.

Need to remember something? Pets and allergies mean frequent checks and replacements are a must. Neglecting this can lead to expensive maintenance down the line. Keep your furnace filter in check and get fresh air. Don’t let neglectful maintenance lead to costly repairs. 

Do it now! Better call a hazmat team before inspecting that filter!

Inspect the Filter for Dirt

When it comes to furnace maintenance, inspecting the filter for dirt is vital. This can help your furnace perform better and last longer. Follow these steps:

  1. Turn off your furnace and let it cool down.
  2. Look for the air filter – usually near the blower motor or return air duct.
  3. Take out the filter and hold it up to the light.
  4. If dirt, grime, or debris is visible, it needs cleaning or replacing.
  5. Consult your furnace manual for guidance if unsure.
  6. Clean or replace your filter (check ‘How to Change Furnace Filter‘ for instructions).

Inspecting the filter regularly can keep indoor air quality healthy and protect your HVAC system. Signs of too much dirt are reduced airflow and musty smells.

Choose the right replacement filter for your furnace, as recommended by the manufacturer. A high-efficiency pleated option can capture more debris and allergens than a standard fiberglass filter. 

Don’t wait until it’s too late – get a new one now!

Replace the Filter with New One

Changing your furnace filter is essential and mustn’t be ignored. A dirty filter can affect air flow and reduce the furnace’s energy efficiency. Replacing the filter regularly will keep your home’s heating system at its peak performance. Here’s how to do it:

  1. Find the old filter – usually in a slot near the blower motor.
  2. Gently take out the old filter.
  3. Check the size and type of filter needed for your furnace – this is on the old filter or in the furnace manual.
  4. Buy a replacement filter from a local hardware or home improvement store.
  5. Insert the new filter into the slot, making sure it fits well.
  6. Set any alerts or reminders on your thermostat or furnace control panel, so you remember to change the filter again in a few months.

Note that if you have pets or allergies, you may need to change the filter more often. Disposable filters should be discarded properly. It can also be helpful to keep track of when you last changed the furnace filter. Put it on a calendar or set reminders on your phone.

One homeowner neglected their furnace filter and paid the price: increased energy bills and poor indoor air quality. Don’t make the same mistake – take care of your heating system by changing the filter regularly! Check your air handler and blower motor too – you don’t want them to break down in the middle of winter!

Checking the Air Handler and Blower Motor

To guarantee your furnace is running optimally, it is essential to inspect the air handler and blower motor periodically. Here’s what to do:

  • Switch off the electricity: Before assessing the air handler and blower motor, turn off the electricity to your furnace.
  • Locate the air handler: The air handler is usually near the blower motor on the inside of your furnace.
  • Search for debris: Check the air handler for any debris that could prevent it from working properly. Take away any big debris manually or with a vacuum cleaner that has a hose attachment.
  • Clean or replace filters: Clean or substitute your furnace filter every three months or as stated in your owner’s manual.
  • Examine wiring and connections: Carefully examine all electric wiring and connections leading to the blower motor. Guarantee all connections are secure and that no wires are loose, frayed, or damaged in any way.
  • Lubricate moving parts (if necessary): If there are any lubrication points visible, put lightweight machine oil to keep moving parts running smoothly.

It’s essential to be aware that depending on your furnace model, these steps may be different. If you are not sure about anything related to your furnace’s upkeep procedures, don’t hesitate to contact an expert HVAC technician. Keeping a regular maintenance schedule for your furnace can not only make it more efficient but also increase its life expectancy.

Time to put the furnace back in the closet. But, don’t forget to cover it up with its access door first.

Reinstall the Access Door

After you change the furnace filter, it’s important to put the access door back correctly. Here’s how:

  1. Fit it into its frame.
  2. Tighten screws and latches.
  3. No gaps around the edges.
  4. Test the furnace.

A loose access door can cause problems; like malfunctioning, energy loss, and costly repairs. So, reinstall the door after changing the filter. If there’s an issue after that, call a technician.

Don’t forget – neglecting your filter is like not having a Tinder profile – you’ll be left with nothing but a cold, lonely night! Be sure to properly reinstall the access door on your furnace after replacing its filter.

Furnace Filter Maintenance Tips

To keep your furnace running smoothly, you need to maintain the furnace filter. One of the most important things you need to do is choose the right size and type of filter for your furnace. In addition, understanding the right frequency of filter change is also crucial. You need to choose between washable and disposable filters, and efficiency ratings may impact air quality. In removing airborne particles and allergens, you can improve indoor air quality. Don’t forget to consent to HVAC system maintenance for optimal furnace performance.

Choose the Right Size and Type of Filter

Size and type of filter are key for furnace efficiency. Knowing what to choose can save cash and time. Here are 3 steps to get the right one:

  1. Measure Up!
    Check the current filter, as size is often printed. Or get help from an HVAC professional.
  2. Types Vary
    Options are electrostatic, pleated, HEPA, fiberglass and washable. Choose based on your needs.
  3. Don’t Cut Corners
    Cheap filters may seem like savings but might not filter out debris or need replacing more often, costing more in the long run. Plus, stick to manufacturer and local guidelines when choosing a filter.

In 1902, Willis H Carrier invented the first air conditioning unit and a basic air filter system to improve indoor air quality – improving health!  

Change your furnace filter regularly, just like taking vitamins – it’s essential for a healthy system, even if it’s not fun.

Frequency of Filter Change

Maintaining your furnace filter is key to make it last and keep your home air clean. Here are some tips on how often you should swap your filter:

  • Normal filters should be changed every 1-3 months.
  • If you have pets or allergies, consider changing your filter monthly.
  • High-efficiency filters can last up to 6 months. Check them each month to make sure they’re not blocked.
  • Reusable filters can be washed every 1-3 months, depending on use and the manufacturer’s instructions.

Various factors can affect filter replacement frequency, like the size of your home, number of occupants, and indoor air quality. If you’re unsure, ask a pro. Mark your filter with the installation date. This small step will save you time and money.

Swapping a disposable filter may be easier, but washing a reusable one can give you a sense of pride… and save you money. #winning

Washable Filters vs. Disposable Filters

When it comes to furnace filters, homeowners have two choices – washable or disposable. Both come with their own pros and cons. To help you decide, here’s a comparison of the two.

  • Washable filters have a higher upfront cost, but they can be reused for up to 10 years if maintained properly.
  • Disposable ones have a lower upfront cost, but need to be replaced every 1-3 months.

The EPA states that dirty air filters are not only inefficient, but also dangerous to health. So, it’s important to keep your filter clean regardless of which type you choose. The worst part? Having to explain to your guests why the air smells like a musty basement.

Efficiency Ratings and Air Quality

You need an efficient furnace filter to ensure top air quality at home. Its job is to trap airborne particles, such as dust, pollen, mold spores, and pet dander. The higher the MERV rating, the better it captures these particles.

Check out the table:

MERV ratingParticles captured
1-4Pollen, carpet fibers, dust mites
5-8Mold spores, pet dander
9-12Fine dust, smoke
13-16Bacteria, allergens

Family members with allergies or respiratory problems? Use a filter with a MERV rating of 9-12. Make sure your HVAC system can handle the extra airflow resistance, though.

Did you know the first furnace filters were made of furnace slag. Arthur Gossner invented them in the early 1900s. These primitive filters weren’t great and needed frequent replacing. Thanks to time and materials, today you have high-rate efficiency options.

Say goodbye to sneezes, hello to pleases!

Removing Airborne Particles and Allergens

Change your furnace filter every two or three months to keep your furnace running smoothly and to help it remove airborne particles. Vacuum or dust your home to get rid of any dust, pet hair or pollen. Use an air purifier to further reduce allergens. If someone in your home suffers from allergies, upgrade to a high-efficiency filter that captures up to 99% of allergens.

Check with your manufacturer about recommended replacement schedules and cleaning methods for your filter. Regular maintenance and minimum pollutants will prevent frequent HVAC repairs and prolong their life cycle.

Take care of yourself and your family by changing furnace filters regularly, vacuuming or dusting, using an air purifier, and upgrading to a high-efficiency filter if allergies are an issue. This way, you can ensure you all breathe clean and healthy indoor air. 

Skipping HVAC maintenance is like agreeing to a blindfolded tightrope walk without checking the rope first.

Consenting to HVAC System Maintenance

Maintaining HVAC systems is vital for peak performance, energy efficiency, and lengthy life. Here are five tips to keep your HVAC system maintained:

  1. Inspect the air filter regularly and replace it every 90 days, or more often if needed.
  2. Check the thermostat settings and adjust them to suit the conditions.
  3. Get HVAC pros to do routine checks and preventive maintenance on your system annually.
  4. Make sure all vents in your home are open and not blocked by furniture or items.
  5. Keep an eye out for any unusual smells or noises coming from your system.

Doing regular maintenance can help your HVAC system run well, but extra care can greatly increase its longevity. Clean outdoor aluminum fins using a soft brush or pressurized air, without damaging the fins’ movement. Mark the replacement date on your new filter to remember when it needs changing again.

Never overlook your furnace filter, unless you want to breathe in more dust than a hoarder’s basement.


1. Why is it important to check the furnace filter regularly?

Regularly checking the furnace filter is important because a dirty or clogged filter can restrict airflow, reduce efficiency, and potentially cause damage to the furnace.

2. How often should I check my furnace filter?

It is recommended to check your furnace filter at least once a month, especially during periods of heavy use, such as winter months.

3. How do I locate the furnace filter?

The furnace filter is typically located near the blower motor or in the return air duct. Consult your furnace’s manual or contact a professional if you are unsure.

4. What are the signs of a dirty or clogged furnace filter?

Signs of a dirty or clogged furnace filter include reduced airflow, increased energy bills, uneven heating, excessive dust in the home, and potential burning smells.

5. How do I remove and inspect the furnace filter?

Turn off the furnace and locate the filter. Slide it out of its slot and inspect it for dirt, dust, or debris. If it appears dirty or clogged, it is time to replace it.

6. What type of filter should I use for my furnace?

The type of filter you should use depends on your furnace’s specifications. Common types include fiberglass, pleated, electrostatic, and HEPA filters. Consult your furnace’s manual or a professional for guidance.

7. How do I know if my furnace filter needs to be replaced?

If the filter appears dirty or clogged, it needs to be replaced. Additionally, if it has been more than three months since the last replacement, it is recommended to install a new filter.

8. Can I clean and reuse my furnace filter?

Some filters are designed to be reusable and can be cleaned according to the manufacturer’s instructions. However, most filters are disposable and should be replaced when dirty.

9. How much does a furnace filter cost?

The cost of a furnace filter varies depending on the type and size. On average, disposable filters can range from $5 to $20, while reusable filters may cost between $20 and $50.

10. What are the benefits of regularly changing the furnace filter?

Regularly changing the furnace filter improves indoor air quality, reduces allergens and dust in the home, extends the lifespan of the furnace, and helps maintain energy efficiency.


Your home’s heating and air conditioning system is unique, so you need to know what type of filter will fit best and what MERV rating is best for your home. Low MERV ratings let more particles pass through, while high MERV ratings will catch more particles, but could affect airflow and efficiency. Don’t ignore your furnace filter maintenance! It’ll harm your HVAC system performance and your indoor air quality. Check your filter monthly and replace it when needed, as instructed by the manufacturer. Protect yourself, your family and pets from bad air! Clean and maintain your furnace filter regularly. Dust, pollen, mold, mildew and more are dangerous airborne particles that can affect people with allergies or pets in the house. Keep everyone safe and healthy by caring for your furnace filter.

About the author

Debarghya Roy: A heating systems author, Passionate about energy efficiency and sustainability, Sharing insights and empowering readers through informative blog articles.