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How To Know When It’s Time To Change A Furnace Filter

Like most homeowners, you realize that your furnace and air conditioner require yearly maintenance and cleaning. You can’t just let them sit while they get oily and gross. Furnace filters are designed to keep dust and other particles out of the system so that everything in your home runs smoothly. While they look simple and contain no hazardous materials, there is a lot that goes into choosing and installing the right filter for your home’s needs.

How To Know When It's Time To Change A Furnace Filter

1. Check Your Filter Every Month

The furnace constantly filters the air in your home, but the filter can become clogged with dust, dirt, and debris. This buildup can reduce the furnace’s efficiency and, over time, cause it to fail. Therefore, checking your filter every month is essential to ensure it’s clean and functioning correctly. 

2. Look at the Condition of Your Filter

If you’re looking to change your furnace filter, the best way to know it’s time is to check the filter’s condition. If it’s dirty and clogged with dust, use a vacuum cleaner to clear out any debris that might be inside.

If you’re unsure whether your filter needs replacing yet, then start by checking for clogs in your furnace’s ductwork. This can be done using a small brush or even a Q-tip with a little bit of water mixed with it. If there are any areas where the ductwork has been blocked or damaged by previous attempts at cleaning it, those areas should be cleaned first before proceeding with more intensive efforts.

If, after doing this, you still have concerns about whether or not your furnace is ready for a new filter, then call an expert who can help you determine what kind of filter will fit into your home’s system best and whether or not any other problems need addressing as well.

3. Check How Long it’s Been Since You Replaced the Filter

One of the most common reasons to change a furnace filter is because it’s been too long since you replaced it. The filter should be changed every 90 days to ensure its effectiveness. If unsure when your filter was last modified, check the date on its box and compare it with the date on your furnace’s warranty paperwork. If you don’t have those documents handy, ask for them from your local service company or contractor.

4. Compare Your Utility Bills 

If you’re like most people, you check your utility bills regularly. But sometimes, even if you live in a state that has a utility grid that’s publicly regulated, your bills can go up without warning. That’s because of your furnace and the filter inside it.

If you want to ensure this doesn’t happen, especially if your bill has increased significantly, you should change your furnace filter regularly. This will help prevent any dirt or debris from getting into your system and causing damage.

5. Think About Whether Your Home is Being Heated or Cooled as Efficiently

If your furnace is working but not heating or cooling your home as efficiently as it could be, it’s time to change your filter. If you have a gas furnace and you’re noticing that your home isn’t getting as much heat as it should be, or if you’re noticing that your air isn’t as cold as it could be, chances are your filter needs to be changed.

6. Look for Dust on the Filter

If you see the dust on your furnace filter, it probably means that the filter needs replacing. Dust can get trapped in a filter and prevent proper airflow. So if you notice that dust is accumulating around your furnace, or if you’re noticing that your heating or cooling system is not working correctly, it’s time to get a new furnace filter.

7. Set a Reminder

Set a reminder on your phone or calendar, so you remember to change the filter every month or two. Then, you’ll be pleased with the results.

8. Look at the MERV Rating

If you want to change your furnace filter, it’s essential to know whether or not it’s time. The MERV rating helps you figure out when to replace your filter. First, look at the MERV rating on your furnace filter. This number measures how much air your filter can block before it becomes ineffective. The higher the number, the more air it can block. This means that if you want to get rid of dust, pollen, and other irritants from circulating through your home, you should change your filter every year or so.

If you have a high-end model with a MERV rating of 10 or better, you should be able to go for two years without changing your furnace filter. However, if it has a lower number (below 10), you’ll need to change it more often.

9. Change it as Necessary When Pets are Present

If you have pets, keeping their comfort in mind when trying to determine the best filter for your furnace is essential.

The main reason is that many pets shed hair and dander, making a filter clog up quickly. In addition, cats and dogs carry fleas, ticks, and other parasites that can cause allergic reactions in humans who come into contact with them. Therefore, it’s best to change your furnace filter every two months or so, no matter what kind of pet you have, as this will keep them safe from parasites in the unit.

10. Get Help from a Professional

If you notice a change in the smell of your air, or if you start to notice that your furnace isn’t as efficient as it used to be, it’s probably time to change your furnace filter.

You’ll want to contact a professional for this step because they can tell you if any other components in your system need changing, too. You can also try looking online for tips on how to DIY this process yourself, but if you’re not comfortable doing so or don’t have the right tools, it’s best to enlist the help of a professional on furnace air filters for sale.


The best way to keep your furnace running smoothly is by changing its filter regularly. While you don’t need to do it monthly, you should change its filter every three months. Knowing the signs that it’s time to swap out the old one will help make the process easier, and you’ll save yourself some headaches in the long run.


  1. Thank you for emphasizing the importance of heating maintenance! It’s crucial for ensuring good operation and clean indoor air quality.

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