Frequently Asked Questions

Who Are We?

The short story:

The website and company was created by Techniques, Inc. so that homeowners like you can enjoy the same high-quality filtration we have been offering our commercial customers for over 30 years. We are based in northern Minnesota and, YES, we are indeed “Minnesota Nice”! We do talk a little funny. If you call us, you may her us say things like “uffda” or “ya, you betcha”. Don’t worry about what that means, just know that we understand your needs and will work hard to earn and keep your business. We’re kind of old fashioned that way.

Why we do what we do:

After providing air, furnace, and water filtration solutions for dozens of hospitals, universities, and office buildings, something occurred to us: If we can offer the best quality, best performing and most cost effective filtration products for these large businesses… We can do it for home-owners, too!

Everybody needs and deserves to breathe clean air in their own home, but not too many people want to spend their time thinking about it. At Techniques, we have built our business around thinking about it, so you can just leave it to us!

From your first filtration installation to managing your replacement schedule, Techniques, and 4QualityAir have got you covered.

So again … WHY do we do what we do? Well, not only are we owners and employees of Techniques, Inc., we are home-owners, too! And we know that in most homes, air filtration isn’t the number one priority. But it’s ours. And we want to help you and your family breathe easy… the way we have been helping our happy, loyal customers for the past three decades.

What Type of Air Filter Should I Buy?

In the residential sector, this is not an unusual question!

A few quick points to note:

  • Generally speaking, the higher the MERV (Minimum Efficiency Reporting Value) Rating, the more effective the filter will be at removing dust from the air.
  • Regardless of the type of filter you choose, the MERV Rating system is the same, based on clean airflow output. – Click here to learn more about the MERV Rating and how it is used to calculate the efficiency of all air filtration products.

There are two main types of residential air filters:

  • Pleated Air Filters (Surface Loading)
  • Graduated Density Air Filters (Depth-Loading)
Pleated Air Filters

Pleated Air Filters are designed to collect (or “load”) the dust on the surface of the pleats. When shopping for pleated air filters, you want your MERV Rating to be at least an 8, like with our DPMAX40 model.

Here is an example of a Pleated Air Filter. The dust loads on the surface of the pleated media.

If you’re looking for a filter with a higherarrestance efficiency, you may want to consider our PowerGuard. with a MERV 11 Rating, or our DP Green 13 filter, with a MERV Rating of, you guessed it: 13.

If you need a filter to control and reduce odors, our AirGuard Fresh Air Activated Carbon Filter is a pleated air filter that incorporates activated carbon to actually remove or reduce stubborn, household odors.

These are great solutions for the fussiest housekeepers … or those who are simply too busy to be fussy housekeepers!

Graduated Density Air Filters

Whenever possible, we highly recommend using Graduated Density Filters. These filters have three layers of filtration varying in density. The first line of defense is the coarse layer, where the air and dust enter, the next layer is a medium layer, which traps the majority of the finer particles, and the final layer actually incorporates a lanolin based tackifier, which ensures the particles stay trapped in the filter, even as the fan cycles on and off, or the filters are replaced.

If we could only carry one type of filter, this would be it! It’s the one we recommend to all of our commercial customers, it’s the one we recommend to all our family and friends and it’s the one we use in our own homes.

Please see our 3-ply Dustlok panel filters, which have a MERV 9 rating.

Graduated density air filters have three layers of filtration preventing dust from traveling through the filter and into your home.They also incorporate a perimeter seal between the filter and the frame, which ensures all of the dirty air go through the filter instead of around it.

Allergies – Your Air Filter Could be Making them Worse!

In addition to dust, does anyone in your home suffer from mold, mildew, pollen, pet dander, or other airborne allergies?

If so, you need a filter that also incorporates an antimicrobial biocide like Spor-Ax.

As air passes through the filter on your furnace, any moisture in the air (and yes—there is usually some moisture in your air, no matter where you live) collects on the filter as well—And you know where mold and mildew like to grow? In warm, dark, damp environments … like your furnace filter!

An antimicrobial agent that keeps these nasty allergens from growing can make a big difference in a house with allergies! – Who knew?? Many people spend spring, summer, and/or fall with their windows shut because they have allergies and maybe part of their problem is inside the house and could be solved with a different air filter.

Again, look for a filter with an Antimicrobial agent like Spor-Ax.

Spor-Ax is registered for use in adhesive and binders in air filters and has the very best safety profile. (EPA registration number: 464-676-68603) This means Spor-Ax is thoroughly incorporated into the individual filter fibers as the filter is manufactured. This process is far superior to the other "Allergy Treated" filters on the market that simply treat the surface of the filter after it has been made.

We have specific air filters we recommend for allergy sufferers (We made it easy for you!). Our Dustlok filter is your best option. This one has a MERV Rating of 9 and also features Spor-Ax antimicrobial biocide and the Dustloktackifier.

But … Maybe you have the opposite problem. Do you suffer from dry, cracked skin or even nosebleeds in the winter months? We can help you here, too!

You may need to add a little moisture to your air.

Humidifier Filters

Humidifier Filters, also called water panels, evaporators, or water pads, can be put inside your humidifier to help alleviate dry air. When air is pushed through the water panels, it picks up the moisture contained in the filters and distributes it throughout the room or HVAC system.

Fiberglass Pinch-Frame Filters
  • If you have an older home, you may have used this type of air filtration
  • These filters utilize technology from the 1950’s
  • They are designed to only trap larger particles from the air (cat hair, etc.)
  • They are not nearly as effective
  • We don’t carry these
  • If you’re currently using these filters and are wondering what kind of filtration to replace them with, please give us a call, toll-free at 1-855-463-3600, or send an email to


What is a MERV (Minimum Efficiency Reporting Value) Rating?

The MERV Rating is recognized as an industry-wide standard for air filtration, regardless of the type of filter being tested. So, regardless of the type of filtration being considered, they are all tested in the same way by an independent, third-party laboratory so that the results are certified.

Want the long version? Read on!

(Or just skip to our helpful "How to Buy a Filter Guide")...

Using the ANSI/ASHRAE Standard 52.2 Test Procedure, an air filter’s performance is determined by comparing airborne particle counts both upstream and downstream of the air filter being tested. The data is collected and the test is then repeated six times. The test measures:

  • How many particles are captured when the filter is in place
  • How small the particles are.

The lowest values over the six test cycles are then used to determine the Composite Minimum Efficiency Curve for that air filter.

Once these values are compiled, the 12 size ranges are distributed into 3 larger groups called E-1, E-2 and E-3. Averaging the Composite Minimum Efficiency for each group will calculate the average Particle Size Efficiency (PSE) of the air filter, and the resulting percentages are used to determine the MERV rating.

The MERV rating is a number from 1-16, stated along with air velocity at which the test was performed, to simplify the evaluation of an air filter using this test method. Higher MERV rating equates to higher air filtration efficiency.

Regardless of the type, most residential furnace filters range from MERV 8 to 13.

Quick Breakdown of the MERV Ratings


  • An all-around “good” filter
  • General dust filters – Very common.
  • Collect most dust and still provide excellent airflow


  • Common upgrade from MERV 8 for those who need even cleaner air
  • Great compromise for those who need increased filtration without reducing their airflow


  • Highest MERV Rating available for standard HVAC filters
  • Extremely good at collecting very fine particles
  • Common requirement for LEED certified buildings


How to Buy a Filter – An "Everything You Need to Know about Air Filtration but were Too Afraid to Ask" Guide

What should I look for in a filter?

Look for the Sweet Spot! Whether we are helping families like yours shop for residential furnace filters, or we are installing industrial filtration in a sterile environment like a hospital, choosing a filtration system is a balancing act between maintaining desired air flow and minimizing resistance, dust holding capacity, and dust removal efficiency.

We recommend looking for the "Sweet Spot."

At 4Quality Air, we are passionate about clean air. Of course we have a Venn Diagram to illustrate how you should shop for filtration!

How Often Should I Change My Filter?

  • A good rule is to change them every 3 – 6 Months (but it depends on your specific situation. Six months can really be a stretch.)
  • It’s hard to tell when a filter needs to be changed just by looking at it. Environmental factors play a major role in this.
  • We recommend just setting a schedule and sticking to it, rather than trying to “squeeze” an extra week or month out of a filter. You spend a lot of money on your heating & cooling systems – Don’t let a lax filtration schedule compromise the quality of your family’s air!
  • Oh—and don’t worry about us running out of your filters. We have plenty!

A Few Pro Tips for Scheduling your Filter Changes

  • The easiest thing to do is write a reminder on your calendar every three months
  • Or, make a note to change it on specific holidays like: New Years Day, Easter, Memorial Day, and Labor Day – This schedule also jives well with the seasonal demands on your filters in most climates … AND it gives you one more exciting activity to do when celebrating the holidays. Am I right?

OK, but WHY Should I Change My Filter?

  • To increase the quality of your indoor air and provide a healthier environment for your family!
  • To save money – Air filters that are replaced regularly help you system operate more efficiently.


How Do I know What Size Filter I Need?

  • Two “Size” words you should know:
    • Nominal Size – The dimensions printed on the filter.
    • Actual Size – The real, physical size of the filter if you measured it with a tape measure.
    • Typically air filters are measured in inches
    • All the measured lengths are measured up to the nearest inch and stated as “nominal”
    • For example, 16 x 25 x 1 is the Nominal dimension if the Actual measurement is 15 ½ x 24 ½ x ¾.

Five Filter-Buying Scenarios You May Find Yourself in and some Quick Solutions:

  • You have an old filter with the size printed on it
    • Woo hoo! Use this information when buying your new filter. Easy!
    • Also note – the length and width are interchangeable – For example, 20 x 14 x 1 can also be 14 x 20 x 1
    • You have an old filter with no size markings
      • Use a tape measure to measure its size – Remember, this will be the Actual Size and you will need to round up to the next inch to get the Nominal Size.
      • Also note – the length and width are interchangeable – For example, 20 x 14 x 1 can also be 14 x 20 x 1
      • If you can’t find a filter that matches this size, we will show you sizes that are close.
      • If you still can’t find a size that will do, we may be able to custom make a filter for you. (Yes—We do that! Talk about a way to impress your guests!) – Please note that custom-built filters are made to your exact dimensions and are non-refundable.
      • You Do Not have an Old Filter
        • Use a tape measure to measure the slot in your furnace
        • Remember – This is the Actual Size. Round up to the nearest inch to get the Nominal Size.
        • Also note – the length and width are interchangeable – For example, 20 x 14 x 1 can also be 14 x 20 x 1
        • It’s also worth mentioning some furnaces take two filters at a time so a slot measuring 16 x 40 is for two 16 x 20 filters. (Don’t worry. You can call us and we will talk you through it).
        • The Filter You Need is for an Air Cleaner that is Located between the Furnace and the Return Duct
          • In this case, you’re not looking for a traditional furnace filter, you need a Media Type Filter.
          • These filters will usually be much thicker than typical furnace filters (Usually between 3-6 inches)
          • You can often find the filters you need based on the Air Cleaner’s model number.
          • Can’t find the Air Cleaner’s model number? You will have to resort to one of the above methods.
          • I know the model number of my furnace – Can you tell me what kind of filter I need?
            • Sadly, no. But we wish we could!
            • Most units do not come with a place to put a filter at all and it is up to the HVAC contractor to custom build one. The exact same furnace could have various filter size needs.
            • Please see the above tips about measuring for your filter.
            • An Exception to this: If you have an air cleaner installed between the furnace and return duct, it will usually use a large filter between three and six inches thick. Usually.


Once I place my Order, When will my Filter Arrive?

  • We strive to ship every order made during our normal business hours the same day it is placed!
  • That being said, certain products, custom orders, or large orders may require additional lead time.
  • Please see below for Shipping Information
  • To track your order, please click here, enter your order number and the zip code used for shipping. You will receive an email with a secure link to view your order.


What Type of Payment do you Accept?

  • We accept all major credit cards via our secure payment center (Visa, MasterCard, Discover, American Express)
  • You can also use your PayPal or Amazon account
  • For questions or more details, please contact: 218.463.3600


Can I Order By Phone?

Yes! Gladly! This is also a great opportunity to ask our friendly, knowledgeable staff about any technical or filtration concerns you have … Between the hours of 9:00A.M. and 5:00P.M. Monday through Friday. Just call 218.463.3600.

What if I Buy the Wrong Filter?

Don’t you worry. Customers are our number one priority. Returns and Exchanges are Free!

  • Contact Customer Service for a Return Label – Or complete the form Here.
  • Stick the label on, put it in the mail, and we will give you your money back so you can buy the correct filter.
    • Product must include original packaging
    • Custom-made filters are non-refundable
    • Returned items must be in the same condition you received them
    • Once your return is received and inspected, your refund will be processed within seven business days.
    • NOTE: Your credit card company may not post the credit to your account for two to 10 business days.
    • We reserve the right to refuse any returned item if the above scenarios or other like situations are unsatisfactory.


What are my Shipping Options?

  • We always offer free standard shipping which will usually get your filter to you within two to 10 business days.
  • Certain products are available for 2-day air or next-day air for an upcharge.


Can you Ship to a PO Box?

  • We ship most orders via UPS or Spee-Dee Delivery Service
  • These carriers are not authorized to deliver to the Post Office so if you require a PO Box delivery, the order will be shipped by the US Postal Service.


What if I am Still Just Not Happy with my Filter Buying Experience at 4Quality Air?

YOU are our number one priority. Period. Our goal is to help you breathe easy. If you are not completely satisfied, please let us know so we can make it right.

As the old saying goes, if you not satisfied, please tell us … If you ARE satisfied … please tell EVERYONE!


Customer Service

If you require additional assistance, please contact our Customer Service Department at 1-855-463-3600 or 1-218-463-3600. A Customer Service representative will be happy to help you.

Please have one or more of the following order details handy when you call:

  • Invoice Number
  • Products Ordered
  • Name and Address Order was Placed Under
  • Method of Payment