How often should I change my 4 inch HVAC filter?

Author: Prof. Jerry Deckow Jr.  |  Last update: Tuesday, September 23, 2025

For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.

How often should I change my 4 inch AC filter?

In general, experts recommend a simple rule of thumb for changing your air filter based on the size: Change 1- to 2-inch filters every three months. (Scheduling filter replacements with the start of each new season is an easy way to remember.) Change 4-inch filters every six months (summer and winter).

How long does a 16x25x4 air filter last?

16x25x4 air filter is designed to last for about 6 to 12 months. But this can vary depending on factors. Like the air quality in your home. And how often your HVAC system is in use.

Are 4 inch furnace filters worth it?

Higher MERV ratings work best when the filter is 4” thick or thicker because they trap extremely small particles, which means contaminants will build up quickly on the screen. If your system only fits a 1-inch or 2-inch filter, a high MERV rating could be detrimental.

How do I know when my HVAC air filter needs to be replaced?

5 signs your air filter needs to be replaced. 😷 1. Dust and Dirt Around Vents. 2. The Filter Looks Dirty or Clogged. 3. Rise in Electricity Bill. 4. It Takes Longer to Heat or Cool Your Home. 5. The AC Unit Is Hot.

How Often Should I Change My Home's HVAC Air Filter?

What happens if you don't change HVAC filter?

If you don't change your air filter, it can quickly become clogged with dust and debris, preventing proper air filtration. This leads to a variety of issues for your HVAC system including system inefficiency, higher energy bills, inadequate air quality, and ultimately failure.

How to know if a HVAC filter is dirty?

If the filter is still in good condition, light should shine through. If the filter is dirty or clogged with debris, the light will be obstructed, indicating it's time for a replacement. The presence of visible mold is another one of the dirty HVAC filter symptoms that indicates it's time for a replacement.

How long does a 4-inch thick furnace filter last?

A three to four-inch filter can last for six to nine months. If you have a thick five to six-inch filter, it can last from nine to twelve months. By making sure that your filters are changed when they need to be, you can enjoy having a heating and cooling system that will work its best.

Do more expensive furnace filters work better?

The higher the MERV rating, the better the air filter is at removing particles. Cheap air filters typically have a low MERV rating of 6 or less, while expensive air filters can have a MERV rating of up to 13. This means that they can remove much smaller particles, like bacteria, viruses, and mold spores, from the air.

What is the difference between 1 inch and 4-inch furnace filters?

Well, 4-inch filters have larger pleats. That means they have more surface area to catch particles, making them last 3–5 times longer than 1-inch filters. Most HVAC technicians recommend changing 1-inch air filters every 30 days, while 4-inch filters can be changed every 3–6 months.

Who makes the best HVAC air filters?

Carrier. Carrier is well-known in the HVAC industry, and their whole-house air filters uphold its reputation for quality. Their filters can fit into any HVAC system, offer high MERV ratings, and effectively capture and reduce a wide range of pollutants.

How long does a 4 inch carbon filter last?

Typically, a carbon air filter lasts between three to six months.

How long after changing the air filter will AC work?

After replacing the filter, you should wait at least 12 hours before running the system. If the AC is still not blowing cold air, it could signify that you have a refrigerant leak, a damaged condenser, or your entire mechanical system needs maintenance.

Will my AC work better if I change filter?

A new, clean new air filter keeps your HVAC unit running smoother and running longer, extending its useful life.

What is a good MERV rating for a carrier?

A good MERV (Minimum Efficiency Reporting Value) rating for residential HVAC systems is typically between 8 and 13. MERV 8 filters capture basic particles like dust, pollen, and pet dander and are adequate for most households.

How much is a new furnace?

Ask twenty professional HVAC contractors the question, “How Much Does A New Furnace Cost?” and you'll probably get the same answer... “It depends.” On average, the cost of a new furnace can range from $2,000 - $14,2001. However, factors like furnace efficiency, type, size, and much more can impact this range.

Are high MERV filters worth it?

What MERV rating you choose between 7 and 13 depends on what level of filtration you require. If your family has allergies or asthma, a higher MERV rating will be good for you. If your family doesn't suffer from any breathing difficulties, a lower filter like a 7 will save you some money on your energy bill.

Which is better pleated or fiberglass air filter?

Fiberglass filters shield HVAC systems by capturing bigger debris but are less effective at filtering small particles. If you're looking to reduce allergies, pleated filters are recommended. Pleated filters are better at improving indoor air quality and may cost a little bit more, but they have higher MERV ratings.

Why are filtrete filters so expensive?

More expensive air filters use more material of a higher quality to better filter your air. The cheapest filters are made of spun fiberglass, which does very little to filter your air compared to materials like paper, cotton or polyester.

When should I replace my 4-inch air filter?

For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.

How can I tell if my furnace filter needs changing?

Signs Your Furnace Filter Needs Changing
  1. There is noticeable discolouration on the filter.
  2. You can see the buildup of dirt and dust.
  3. You find your home needs dusting frequently.
  4. It seems your HVAC system is cycling longer.
  5. You realize it's been several months since you've replaced your filter.

Is it okay to double up furnace filters?

In conclusion, while the idea of stacking two filters might seem like a shortcut to better air quality, it can lead to more harm than good.

Why is my furnace filter so dirty after 2 weeks?

If you keep experiencing this situation in your home, we recommend you start with a whole-house duct cleaning to eliminate most of the excess dust and dirt in your home's HVAC system. Then, consult with one of our expert heating and cooling technicians to find the optimal filter for your HVAC system.

How much do HVAC filters cost?

Filters with a MERV rating of 1 to 7 typically cost between $5 and $20. Filters with ratings of 8 to 13 can cost anywhere from $20 to $150. HVAC systems in residential homes usually don't need (and often cannot handle) filters with a MERV rating of more than 13.

How many runtime hours to change furnace filter?

The good news is that you can expect to change your filters every six months or after 150 continuous hours of usage, whichever comes first with these types of systems. However, if the unit is at least 10 years old, then you may want to replace your filters every three months.

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