Air Filter Facts and FAQs
About your Air Filter(s)
About your On Time Air Filters Selection
Selecting Your Filter(s) at On Time Air Filters
Choosing a Filter Quality -- What Is a MERV Rating?
Benefits of Regular Air Filter Replacement
How Does On Time Air Filters Work?
Why should I change my air filter?
1. A dirty air filter is the #1 reason for HVAC system failure. A dirty filter restricts the air flow into your HVAC systems air handler. This restricted air flow places additional strain on the air handler fan motor and could, over time, burn out the motor and cause your system to overheat and ultimately fail. Filter replacement is a small price to pay to extend to life of one of the biggest financial investments in your home.
2. A dirty air filter makes your fan motor work harder and consume more energy. One of the easiest and quickest ways to reduce your energy bill is to replace your air filter.
3. A dirty air filter reduces the air quality in your home. Poor home air quality can aggravate allergies and asthma, particularly children’s allergies. Change your filter for your family’s health.
4. A dirty air filter makes your heating and air-conditioning systems and your ducts get dirty faster. This can lead to costly cleaning expenses or to a need to replace your units sooner than you expected.
5. A dirty air filter increases your energy bills. You can see an immediate, short-term cost saving s when you replace your air filter.
6. A dirty air filter increases your carbon footprint. Changing your filter reduces the amount of energy your home consumes. It’s an easy and inexpensive way to be environmentally responsible.
Where is my air filter located?
Your air filter is most likely located right next to your furnace or air conditioning system air handler. The air handler is the large box containing the fan and fan motor. The air handler pulls air in from the house through the “return” duct system, and then blows the air through the heating or cooling system and back into the house through the duct system. The air filter is typically located at the point where the return duct enters the air handler. Look for a 1” wide hinged or removable cover. The air filter will be inside.
Increasingly, air handlers are being installed in attics. This sometimes limited space will require installation of the air filter in the return. The filter is accessed by removing the grate covering the return duct. It is now unusual to have several returns in a house, with an air filter installed in each return.
Many houses have more than one HVAC system. Each system will typically have at least one air filter. Therefore your house may have air filters located at the air handler AND in the returns. You should check each possible location to make sure you have located all of your air filters.
What are my air filter dimensions?
Air filter sizes come in a variety of dimensions. The most common width is 1”, but height and length will vary by manufacturer. Most standard filters print the dimensions on the filter frame. You can use those filter dimensions to select the appropriate size replacement filter.
Unfortunately, some filters are not marked. In this case you will need to measure the dimensions of your existing filter. Please measure them twice before entering your filter size into the filter wizard on OnTimeAirFilters.com.
Please also be aware that many filters may have actual dimensions that are not exact whole numbers—for example 17½” x 23¾” x 1”. If this is the case, you should round the fractional dimensions up to the nearest whole number. In the example, this would require a filter with nominal dimensions of 18” x 24” x 1”.
Want more help picking the correct air filter size for you? Check out our "pick the right filter size" page. It's full of great advice and detailed instructions. If you still aren't sure, please contact us and we'll do our best to help.
What standard and custom filter sizes does On Time Air Filters offer?
On Time Air Filters offers a huge selection standard home air filter sizes. You may think you have a custom air filter or a hard-to-find size for your air filters. You may have no luck finding it at Home Depot, Lowes or your local hardware store. If that's the case, you've come to the right place for standard and custom air filters.
In fact, many of our standard sizes are treated as custom sizes by the big box retailers and local hardware stores. We treat them as standard, we fulfill your orders in less then 48 hours, and we charge you as if these are standards. Check out our complete list of standard and custom air filters now.
Does On Time Air Filters offer custom home air filter sizes?
Yes! If you can't find your filter size in our impressive list of standard air filter sizes, contact us about ordering a custom home air filter cut to your specific dimensions. And the best...once you place your order, you'll never have to worry about finding your custom home air filter again. We'll ship it to you on your schedule automatically. What could be easier?
When placing your order, click the “I can’t find my filter size” button. You will be able to input any nonstandard filter dimensions you require. Please make sure the dimensions that you enter are correct. We cannot accept returns of custom filter sizes. Click here for information about how to measure your home air filters.
Custom home air filters can be a serious pain in the neck, but not if you sign up with On Time Air Filters. You'll never have to worry again!
How Did On Time Air Filters Start?
On Time Air Filters was created by Sue Heilbronner and Mark Leffers, who grew extremely weary of forgetting filter replacement for a year and then coming up empty at the hardware store.
What if I can’t find my filter size?
On Time Air Filters offers a huge selection of standard air filter sizes in 1", 2", 4" and 6" widths. You can see the complete list here. However, you may have a filter with dimensions that do not match any of the standard sizes. Don’t worry, we have the solution. We offer a custom air filter service to meet your needs. When placing your order, click the “I can’t find my filter size” button. You will be able to input any nonstandard filter dimensions you require. Please make sure the dimensions that you enter are correct. We cannot accept returns of custom filter sizes. Click here for information on how to measure your hvac air filters. Learn more about replacing your air filters here.
What kind of filter should I use?
You should use an air filter that offers the highest level of efficiency without damaging your HVAC system. Air filter efficiency is the measure of how well the filter does its job of filter air before it enters the air handler. An air filter “cleans” the air by serving as a physical barrier to particles hanging in the air. Manufacturers use a number of materials in air filters, such as fiberglass. Additionally, configuration of these materials can impact the filter’s efficiency. For example, a pleated air filter provides greater surface area to trap particles than a flat panel filter and will thus capture more particles even if made out of an identical material. A wider filter—say, 2” instead of 1”—will similarly capture more particles.
You may be surprised to learn that simply using the most efficient filter available is generally not the right answer. This is because as filter efficiency increases, there is a corresponding increase in the level of air flow resistance. A highly efficient filter may restrict air flow to a level that will damage your HVAC system by placing additional strain on the fan motor. Most oder HVAC should use a filter having a MERV rating no higher than 11. Older systems should use a filter with a MERV rating of only 8 or lower. Some older systems are required to use a flat panel fiberglass filter that offers minimal air resistance but which regrettably provides little if any air cleaning at all. These filters carry no MERV rating at all. At the other end of the spectrum, a filter rating higher than 11 is usually overkill for most residential requirements and is generally needed only for extreme allergy environments. For this reason, the highest efficiency rating OTAF offers is MERV 11.
Learn more about issues involved in picking replacement air filters here.
What is Better? Best? Best for Pets?
Our Better home air filter is a MERV 8 filter, which provides superior efficiency at an economical price. This filter is constructed of 100% synthetic media with 10 pleats per foot and sturdy die-cut beverage board frame. MERV 8 means this filter will filter on average over 90% of the particles between 3.0 and10.0_ microns. This includes pollen, carpet and textile dust, mold, spores, hair spray, fabric protector, dusting aids, and cement dust. We offer our Better filter in 1” and 2” thicknesses to fit just about any home application. Learn more about MERV 8 and the MERV efficiency rating system here.
Our Best home air filter is a MERV 11 filter, which offers the highest efficiency level appropriate for most homes. This filter is constructed of 100% synthetic media with 14.3 pleats per foot and sturdy-die cut beverage board frame. MERV 11 means this filter will filter on average over 95% of the particles between 1.0 and 3.0 microns. This includes pollen, carpet and textile dust, mold, spores, auto emissions, flour, and humidifier dust. We offer our Best filter in 1” and 2” thicknesses to fit just about any home application. Learn more about MERV 11 and the MERV efficiency rating system here.
Perhaps we should have called this filter option “Best for Owners of Pets that Carry a Scent that is Not Always Rosy.” That name was unwieldy, and just a bit insulting to our feathered, furry, scaly friends. Best for Pets is a wonderful solution for homes that require deodorizers or other ameliorating treatments for pet scent (or any kind of persistent odor). Our “Best for Pets” filter is rated MERV 8 and is identical to our “better” filter but with the added benefit of activated carbon media to absorb pet and other odors in your home. The activated carbon media removes a wider range of odors, and the MERV 8 rating means goodbye to all but the tiniest of particles.
If you elect one or more filters in the Best for Pets category, you’ll be a serious trendsetter on your block. This technology is fairly new, and, as such, we do not carry carbon-treated filters in some sizes. We apologize, and we expect to expand the reach of this product soon.
In addition, if you do elect a carbon-treated Best for Pets filter, we recommend re-shipment ever 2 months at a minimum. These filters will not stand up in odor protection for more than 60 days, although the filtration benefits will continue for the recommended 3-month reshipment.
What is a MERV rating?
MERV stands for Minimum Efficiency Rating Value. This is an industry standard rating system that allows you to compare filters made by different manufacturers. A MERV rating is a numerical value ranging from 1 (lowest efficiency) to 16 (highest efficiency) and tells the consumer how well the filter captures and holds dirt and dust of a specified size range. The chart below shows the MERV ratings, corresponding particle size ranges, and efficiency level as measured by the percentage of particles captured. Learn everything you ever wanted to know about MERV air filter ratings at On Time Air Filters. Want more help in choosing a replacement air fiilter?
Should I use the highest rated filter available?
No. You should use a filter rating that corresponds to the requirement of your HVAC system. If you are not sure contact your installer and HVAC maintenance company.
Using a filter rating that is too high for your HVAC system may cause damage. Higher rated filters offer resistance to air flow that may place too much strain on the fan motor in your air handler, leading to HVAC system failure.
Using a filter rating that is too low will prevent you from maximizing the level of clean air in your home.
It is worth the effort to get this right. Call your HVAC system installer or maintenance company and ask them what air filter MERV rating they recommend for your system. Learn more about choosing a replacement air filter here.
Why should I use a high efficiency air filter instead of the less expensive blue fiberglass filter?
A more efficient filter is more effective at removing particles from the air as it enters your HVAC system. Conversely, a less efficient filter allows more dirt and dust into your system. This dust and dirt will either land somewhere in the system or circulate back into the house. Dust and dirt on critical parts of your HVAC system will increase your fuel consumption and increase repair and maintenance bills. Dust and dirt circulated back into your home is just plain unhealthy. Who needs that?
Ironically, the effectiveness of low efficiency air filters actually increases as the filter loads up with dirt and dust. There are two problems, though. First, it takes time for the filter to be loaded enough to get a beneficial effect so that everything that gets by the filter ends up either in your system or back in your home. Second, eventually the filter can become so dirty that the system experiences a pressure drop which can burn out the fan motor. To prevent this you have to change the filter, which takes you right back to the first problem. For the brief time that you get a small benefit from your low efficiency filter is far outweighed by the problems it creates.
A high efficiency filter is immediately beneficial because it works right away. This filter also needs frequent changing for the same reason—it can become overloaded and damage your system.
The cost-benefit equation is simple: For a few extra dollars you can ensure that your HVAC system is as clean as possible and the air in your home is effectively filtered just by using an efficient air filter that is changed regularly. It’s a simple task that OTAF makes even simpler.
Will I save money using a more efficient filter?
Very likely. This really depends on where you live and how you use your system. Experts have estimated that the average cost reduction derived from using a high efficiency filter is approximately 10%. This cost savings includes the reduction in fuel consumed by your HVAC system, and reduced repair and maintenance costs. This does not include, however, the cost of system replacement resulting from failure to replace your filter.
It's important to note that there are other ways of improving your overall home efficiency to complement regular filter replacement. Upgrading HVAC units to high-efficiency units, replacing dated home insulation with efficient home insulation, and upgrading or repairing old windows all help to make your home more efficient and green.
Will I have cleaner air in my home by using a more efficient air filter?
Absolutely. A more efficient air filter is designed to do a better job of cleaning the air as it enters your HVAC system. Clean air into the system means clean air is circulated back into your home. That’s great news for your family’s health.
Should I use the most efficient air filter available?
Probably not. What you should use is the most efficient air filter that is appropriate for your HVAC system. Some filters are so efficient that they will reduce the level of air flow through system. This could cause the fan motor to burn out. The most appropriate air filter for your system depends upon a number of factors including its age and the fan motor design.
Most HVAC systems installed recently can accommodate a MERV 11 filter. Generally only severe allergy situations require a system that can handle an air filter with a MERV rating higher than 11. Whole house air cleaners, for example, are designed to scrub the air of all but the tiniest of particles and use up to a MERV 13 air filter. Hospital operating rooms employ systems that use HEPA filters rated even higher. Installing a filter rated higher than MERV 11 in most home systems installed today is not advised and may void the manufacturer’s warranty.
Older systems should probably have a MERV 8 air filter. You can also use a MERV 8 air filter in a newer system. The efficiency level is lower but so is the filter cost. It is a cost-benefit decision that is available and is certainly a better option than sticking with the old, inefficient blue fiberglass air filter.
How long will my filter last?
Filter replacement frequency varies from house to house and from place to place. OTAF air filters are designed to last up to 90 days before needing replacement. If you have pets, or if you live in a location that has more dust, pollen or similar air particles, you may need to change your filter more frequently. We recommend checking your filter monthly. If you see that it is becoming dirty more quickly, you can sign into your OTAF account and increase the frequency of your filter deliveries.
Shipping is free!!
Price for first filter per shipment:
Better (MERV 8 pleated air filter) - 1" - $16.95; 2" - $22.95; 4" - $28.95; 6" - $34.95 (add $3.00 if height or length exceeds 26")
Best (MERV 11 pleated air filter) - 1" - $18.95; 2" - 24.95; 4" - 32.95; 6" - $38.95 (add $5.00 if height or length exceeds 26")
Best for Pets (MERV 8 pleated air filter with activated carbon) - 1" - $25.95; 2" - $30.95; 4" - $35.95 (add $5.00 if height or length exceeds 26")
Certain filter sizes are custom and require an additional charge. These filters are marked with "custom" beside the filter size on the Pick Your Filter page
We discount each additional filter per shipment.
You pay standard price for the most expensive filter in each shipment. For one- or two-inch filters, each additional filter per shipment is discounted 50%. For any filter of more than two-inches in thickness, you’ll receive a 20% discount on every additional filter. This is simply to account for shipping costs of these larger products, but still a material savings over retail.
We discount for increased delivery frequency.
Increase your filter replacement frequency to every 60 days and take 5% off each shipment, or
Increase your filter replacement frequency to every 30 days and take 10% off each shipment.
Our air filter selection wizard automatically applies all discounts as you build your order! You can see the per shipment price change as you add or delete a filter, change filter quality, or modify your delivery schedule. Your average filter price will be very competitive with those of the big retailers and local hardware stores, BUT we deliver your filters right to your home on your schedule!
After you select your filter number, filter quality, and delivery schedule, you will see your per-shipment delivery price in Step 4 of the Air Filter Wizard. On Time Air Filters will bill your credit card or Pay Pal account for this amount each time it ships your filters on the schedule and terms you have selected. You can modify your delivery settings or cancel your service at any time in accordance with the On Time Subscription Terms. Please feel free to email firstname.lastname@example.org or call 1-800-247-0566 with any questions.
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