Home Air Filter 101


Your filter isn’t there to protect you.

Despite what you think, your filter exists to protect your unit.

I bet you also think you’re changing them often enough.

How Often Should You Replace Your Filters?

You should change your filters every 30-60 days. Some more expensive filters say they’re good for up to three months, but by the third month, they can be taxing on your system. If you have a 5-inch media filter, however, they can last 6 months to a year, depending on your home and your lifestyle (if you have pets, children, etc.).

If your home has a lot of people or pets, try to change your filters even more frequently. If you don’t have the right type of filter, you could end up needing to change them more often.

Types of Home Air Filters

You probably know what size filter you need, but do you know what type of filter is best? You need a filter that stops dust, but still allows air to flow. Filters protect your furnace by stopping dust before it reaches the key components. Dust can coat your evaporator coil, overheating your furnace and overworking your air conditioning. Dust can also weigh down your blower wheel, causing the motor to overheat, leading to damage.

According to one of our technicians, “Your furnace recirculates all the air in your home about seven times every hour.” That’s a lot of air! When you think about how much air your furnace has to circulate, it’s easy to see how dust can get in the way. Dust makes your unit work harder to move that much air. When your unit constantly has to work harder, it can get burnt out faster than a college kid during finals week.

There are so many filter options in stores, it can be tough to know what to pick. That’s why we wrote this article! You don’t have to be confused anymore—we want to make selecting a filter easy for you.

Mesh air filter

Fiberglass Mesh Filters

These filters are thinner than a New Yorker’s patience. You’ll be able to identify these easily—when you hold them up, you can see your hand through them. Because they’re so thin, they allow tons of airflow, but they’re horrible at catching dust and debris. These filters don’t protect your unit.

Tightly pleated filter

Tightly Pleated Filters

When you go to the store, you’ll notice filters are rated by something called MERV (minimum efficiency reporting value). The MERV rating refers to how tight the pleats are on the filter. A higher MERV rating means tighters pleats.

Some filters have tight pleats that make them appear thicker (less see-through). At first this might seem like a great thing, but these filters get dirty fast, and then your unit’s going to have to work harder. It would be like you running a marathon with a sock in your mouth—you wouldn’t get much air, and you’d be working harder than ever to breathe. A MERV rating of 13 or higher is too thickly pleated. These filters protect your unit from dust, but they can cause overheating.

Washable Filters

In theory, a washable filter sounds like a great idea! It saves you money and it seems less wasteful. Unfortunately, most people are less likely to pull their filter out and wash it than they are to replace it with a new filter.

Even if you’re on schedule with your filter washing, it’s difficult to get the filter thoroughly clean—there’s often still debris caught in the fibers. Over time, washable filters will also begin to break down and become less effective.

Carbon air filter

Carbon Filters

There’s a new filter coming out! You’ve probably seen carbon filters used with water to filter out taste and odor for many years. Recently, people have started using special carbon-coated air filters. At first glance, these don’t seem like something you’d want your breathing air flowing through.

Typically, a clean filter is white. When a filter is dirty, it starts to look grey and dark. Carbon-coated air filters start off black. We at Morris-Jenkins don’t have a lot of feedback on these types of filters yet because we haven’t tested them.

The Solution

If fiberglass mesh filters don’t catch enough dirt, but thick pleated filters don’t allow enough air through, what option is there that takes care of your unit and your family?

Pleated filters are the best option for your unit, but not the tighter pleats. Filters use a form of measurement called a MERV rating. The higher the MERV rating, the tighter the pleats. A MERV 13 would be too high. MERV 6 would be too low. Something like a MERV 8 (wide pleats) would be, in the wise words of Goldilocks, “just right.”

Technician with air filter1

Absolutely Don’t Make These Mistakes

Pre air filter

Install a Pre-Filter

Don’t install a “pre-filter.” Some people have a filter at their furnace itself instead of at the grill/vent. If this is the case, you don’t need an additional filter at the grill/vent. This would stop the flow of air too much.

You don’t need to buy material to place in front of your filters to act as another form of a “pre-filter.” Remember when we said your unit needs proper airflow? Sure, that pre-filter material stops more dirt and debris from entering your unit, but it also stops air from entering. In order to keep that proper balance of stopping dust and allowing airflow, it’s best to stick with just the simple wide-pleated filters. You also don’t need to put any kind of filter or material over your floor vents/registers because this can also restrict your airflow, overheating your furnace and damaging your system.

Blocked air intake

Obstruct Your Intake Vent with Furniture

We know the vents may not be pretty or in the best place for the look of your room, but we don’t recommend putting couches, bookshelves, or other large furniture items up against your air intake. This is another common way that people accidentally restrict the airflow of their unit. If you truly want to put furniture up against the air intake, we recommend leaving a few inches of space between the intake and the furniture.

Extra Allergy Protection

A lot of people have bad allergies. If a wide-pleated filter doesn’t feel like enough protection for your family, you’d love to hear about air treatment systems. Ask your tech about 5-inch media filters! They’re changed less often than standard filters, but they do a great job keeping your air clean. They also pair well with air ionizers.

An air ionizer can help treat the air in your home, killing allergens and growth in the air and even stopping the spread of viruses. Ask your technician about this option if you want to purify the air in your home!


We Make It Easy

When you schedule maintenance with Morris-Jenkins, ask your tech about filter replacements! If you already have some or would like to purchase replacements, your tech can install them for you while working in your home. We make filter replacements easy!

Even though your filter is meant to protect your unit, it still affects the air you breathe. The better the filter, the better the air for your unit and your family.

You could either buy a good filter, or be a filter.

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