Air Filters and Home Depots Dirty Little Secret

Do you buy air filters for your house?  What am I saying… of course you do. Just about everyone does.

Are you over paying for air filters?

You probably are.   I did.  For 7 years I overpaid.

Then last year I discovered that if I buy them here online in bulk it's much cheaper. And this year when I went to do some research for this article I discovered that some companies within the air filter industry are trying to pull a fast one on YOU!

air filter tips and discounts

Look - I'm not a conspiracy nut or something like that.  I'm just a Dad who has a family to support and a house to keep up.  I take out the trash and I change the filters - these are some of my best contributions to the house.  That… and my insane knowledge of how to hook up electronics.

I know this is my basement finishing website but I thought you guys would appreciate hearing my story and getting less expensive filters (of the same quality).

First, let's start with why I'm angry at Home Depot.


At some point last year Home Depot stopped selling filters that list their MERV rating.  Instead they use a rating call FPR.  It doesn't matter what these stand for what matters is the MERV is a universal industry rating and FPR is a made up rating by the manufacturer.

I talked with Sanjay, at my Home Depot in Reston VA,  for about 30 minutes about this and he said he didn't know about MERV ratings and couldn't tell me what the equivalent FPR would be.

Really Sanjay…?   Well that's shocking!

Especially since you are self-proclaimed filter department guru here at the HD.

I'm mad at HD because without the MERV rating it's very difficult to compare their pricing with the pricing online or at other retailers.

Get Furnace Filters at 50% Off

Let me get to the guts here.  A MERV 8 "equivalent" filter at Home Depot is between an FPR 7 and FPR 9. The price is around $10.97 per filter.  A MERV 8 rated filter online is $6.99. And if you buy 12 or more during an order (which I recommend) then the price drops to $4.99.  (all pricing was as of Dec. 2014)

The price is the same regardless of filter size - that's the same at Home Depot or online.

Orders using Amazon Prime get free shipping. If you use this Amazon affiliate link I already have the sizes and MERV rating in the search box, you can just adjust it to find what you need.

cheaper air filters merv 8

Air filters full box

Here's my stack of filters (3 years worth). The kids are into the game MineCraft. Charlotte's pretending to be a creeper. Kids love boxes!

Order an Entire Box

If you're trying to find time to finish your basement or anything in life for that matter you need to MAKE time where you can.

Buying air filters is a waste of time.  You have to remember the size, go to the store, find the right brand and do this 3 or 4 times a year.

Instead you should go online, order a full box of filters  (there are 12 in a box).  Now your set for at least 3 years. You get the discount and the free shipping.

You're going to buy filters, no matter what, so you might as well save time and money.

MERV 8, The Only MERV for ME

Use MERV 8.  You don't need anything higher (and more expensive) to protect your HVAC.  If you have allergies, try a higher rating, but if you don't notice a difference (fewer symptoms) go back to 8. Try a dedicated air filter appliance instead.

Don't believe the hype of FPR.  It's strictly a marketing plow.  I'm not saying Home Depot filters (Honeywell and Rheem) are bad.  I just think they're mis-leading and over priced.

By the way, the brand I buy is called 'NaturalAire'.  But it really doesn't matter - the MERV rating is what matters.

You can buy the next level down from MERV 8 but most of the websites I investigated and A/C guys I talked to said going lower than 8 could harm your HVAC unit.  From what I can tell FPR 4 at the HD is a level below MERV 8.

A Few Thoughts on Air Filter Life

All of the standard home air filters are rated for 90 days.  Regardless of rating they are all set to work for about 90 days.

But! Not just any 90 days. 

If it's spring or fall and you're not running the air very much then your filter can go longer.  It's just sitting there it's not collecting dust and junk.

To really know when you need to change it you need to look at it.  Does it look grey to dark grey?  Probably time to change it. If it's not greyish then don't change it, even if it as been 90 days.

Of course, the opposite can be true.  We had a long haired grey cat (R.I.P. "Mouse") and our filters needed to be replaced every 60 days or so during the heavy winter months.

Oh, and don't delay changing it because you want to save money.  An A/C unit with a dirty filter uses more electricity to pull the air through - I did the math (yes, I'm a big nerd) you're losing more money by not changing it.

3 Tips to make Filter Changing the Ultimate fun

air filter knife

I use this knife for other things, but above all its my air filter knife.

I now have about 12 years of house ownership experience.  So I like to think I know a thing or two about how to do shit around the house (pardon my language, but I'm old).  Here are some tips I've learned along the way.

1. Dedicate a knife just for filter changing.   Here's mine.  I use it to cut open the plastic wrapping, prior open the latch on the grate and sometimes pry out the filter if it's really stuck in there.

2. Protect your carpet by using the plastic or paper from the new filter to hold the dirty filters until your done. I have 3 to replace upstairs, this makes it easy.

3. If you buy the wrong size (not that I did, I'm just sayin'… suppose you did) outline the size you need and use some scissors to cut it.  Works fine without the frame on two sides.

cut air filter to fit

Final Word on Air Filters

Buy them online and save about $60 on a box of 12 versus a retail store.  For me, with 4 filters types (1 in the basement and 3 upstairs) I saved  $239.36. 

basement finishing jason 205

WOW!  I shocked and saddened that I had so much to say about air filters.  But… it must be said. I'll counter it this weekend with a lot of foosball and Miller Lites to keep the universe from tipping over.

Leave a comment below if you've got some more filter knowledge or tips.

Cheers -  Jason

I am an affiliate for Amazon. This means that if you use the links in this article I earn a small commission   This in no way affects your price nor does it influence my opinion of the company. The commission I earn helps support this website and fund my future basement theater room. Just wanted to be upfront with you.  Thanks for supporting the site!

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Questions and Comments

Click here to ask a question or leave a comment.

  1. Matt says

    Some things just need to be said. Thanks for saying them.
    I too am getting old and pissed about proprietary rating systems.
    Thanks for the follow up. How did you eventually determine FPR 7-9 was MERV 8?

    • says

      Hey Matt - I did some research and read a few articles on this. Based on the testing results and pricing tiers This is about where the MERV 8 falls. It also makes sense from a marketing stand point. Home depot wants to charge more for the same filter so they're rating nicely comes in at a 9, which is higher than 8. Of course, a lot of people won't realize that it's a 9 on a completely different and arbitrary scale. So they charge more because you "think" you're getting more. But to me, you're just paying more - a lot more. - Jason

      • FLR says

        This is incorrect. MERV 8 is roughly FPR 4 or 5. For example, the washable WEB filter is sold at HD with FPR 4 (green coded) and MERV 8 elsewhere. The red coded FPR 7 filters at HD are roughly MERV 11 and the purple FPR 9 are roughly MERV 13. We don't know exactly because HD's FPR test is proprietary, which is ridiculous. The goal is to induce you to buy the over-priced purple or black filters.

    • says

      I love your emails. I am currently finishing my basement by myself. You are an inspiration when I am feeling lazy and a wonderful source of knowledge. And all this presented with a bit of humor! Thank you!

  2. Matt says

    On the Home Depot site, they post that FPR 7 & 9 are both MERV 11. Of course, everything on the internet must be true.

  3. Bubba Bouy says

    Home Depot sucks!!... Buy the correct size filters. Do not waste your time cutting them down McGeiver. They will not seal properly in the return air filter grille after you cut them. MERV is the industry standard for air filter rating. FPR is just a number, it means nothing.

    • Lapoljo says

      I agree with Bubba. You lost a few cred points in my book when suggested "cutting down" an oversize filter. The frame of the filter provides structure AND assures a seal against the furnace frame. Cutting two edges of the filter down means you have 45" of unreliable edge seal for dust to leak around the filter. Not a good thing, and not worth the risk.

      • says

        I hear you, and I agree. But my cut was edge tight and fit snuggly against the 1/2" lip of the air intake frame. I would not recommend cutting a filter if you can't see how it's resting on the frame - the slide in type (like in the basement) would be one example. But upstairs my air intakes are in the ceiling and I can see exactly how well they are fitting. No gaps. Point well taken though - you're right - you do not want ANY gaps along the edge of your filter. And preferably, just buy the right size! - Jason

        • Mike J says

          1) I agree with Bubba, I am an HVAC Tech. Do no cut down filters, wether you feel they are "air tight" or not. This could come loose and get sucked right into the Blower Wheel causing wheel damage and motor failure.

          2) MERV rated filters are the only thing I would recommend for cost saving paper filters. Even the MERV 13 filters only catch about 4-5% of all dirt and dust down to 1 micron in size. What you can see floating in the house is 5 microns or larger. This will still cause alot of dirt and dust in the house to be constantly circulated and you will need your ducts cleaned every 5-7 yrs per the EPA and field Experience has shown the same.

          3) the only way to get rid of 97% of all dirt and dust in the home is an Electronic Air Cleaner. More costly upfront, but will almost eliminate build up on blower wheels/ ac coils (which cause alot of overheating issues), and to breath better cleaner air down to .007 microns in size. This is proven per many studies over the past 7 yrs. They do make them now with disposable throw away media pads instead of using those old Honeywell Air Cleaners with the giant cells that stop working well after a couple of years because nobody cleans them properly. Which brand new they only stopped about 45-50% of all dirt and dust in the home.

          • I did it says

            I totally agree with Mike J about electronic air cleaners. If installed during new construction or when installing a new AC /heating unit the additional cost is small, $900 to $1,100 range. Since the electronic cleaner is after the filter it is very easy to learn the difference between a MERV 4 and a MERV 8 filter. The electronic filter will be working hard and the static charge will be talking to you.

  4. Mary says

    Those disposable furnace filters are sooooo expensive nowadays, it makes me shudder. We home owners, mostly working middle class, taxed to death by the local and federal governments: income tax, real estate tax, car tax, sales tax, etc, etc, ,not much left in our pockets to keep up with the raising prices of food and other necessity, one of them is the furnace filters!
    Thank you for writing this article, every dime we can save counts.

    • Retired says

      Electro Static metal Filters..
      Cost $30
      Remove them once a Month during Heating Season, otherwise every 3 mos rest of Yr when only use your A/C
      _Use anykind of Decent Spray Cleaner- Even Vineger and Water or Some Bleach cleaner
      Spray it on in the utility Sink, let it set for a Few min, hose it off.. let dry for a Few Min\Done deal.. We do ours When do Laundry in same Utility room
      Just use a FPF or wather of 7 or Higher..
      And Buy On Line? Sure, after pay Shipping costs? Your paying the same vs In a Store.. Aren't you?
      And remember, The higher the Rating, the thicker it is and Less Air and heat Gets thru..You will have to Set your Blower to run an extra 1-2 min Longer every cycle...

      Top Electronic Cleaners are the Best.. but Cost $ 2-$300
      and Clean your Ducts! Every Year Minimum..
      a Simple HD Vacum with a 10 ft Extension Hose is all you need.
      Do every Floor Vent..
      Spray with LYSOL when done..

      We also Run a Seperate Air Cleaner In the house.. -On a Timer..
      On Low Speed..

      • Mike J says

        Some info on electrostatic filters. These only have electrostic properties right when the motor turns on and then dies off quickly. Not very effective and more of a gimic.

        I am a HVAC Tech and pleated filters, metal washable or even plastic washable only collect a small amount of the dust in your home. I explained in an earlier reply to Jason about some of the Benefits to Electronic Air Cleaners. Keeping the blower and ac coils clean and keeping your ducts clean are just the mechanical and air flow parts of air cleaners.

        I always educate my customers on the differences of filters to air cleaners. My own Brother was one of them. Used $1 mesh filters and had 2 surgeries on his deviated septum for Allergy problems. For Christmas a couple yrs ago I Installed the Air Cleaner and UV light for germs in his system and he is now virtually symptom free for 2 yrs. And it was like pulling teeth to get him to do it. Now he can't thank me enough.
        Filters are cheaper, but cause more maint and cleaning of the system.

        Cleaning your own ducts may seem easy, but have you ever stuck a camera down there past your 10 foot hose? Its bad. Have you ever inspected underneith your AC coil on the Furnace? Have you ever Looked at the blower wheel build up? 1/20" of dust means you lost 20% of your ability to scoop air.

        Filters are cheaper up front but still cost you more cleanings in the future. AC Coil build ups have looked like Carpets and cause your furnace to Short Cycle because ethe air can not get past the coil in heating mode and shuts the unit down after a few minutes. Blower build up has cause motors to become out of balance and cause premature motor failure.

        Real HVAC education from an actual NATE certified Technician can have you spend a few hundred upfront, but save you thousands and make your systems last a lot longer...

        • says

          Hey Mike - This is great info! I just ordered a couple of different air cleaners to see if it helps with my wife allergies. I'm putting one right in our bedroom. We have 2 cats so this could definitely help out. IF they work I'll post a separate article back and link to it from this one. Perhaps I could also pick your brain more about the whole house cleaners and how they can help to increase the efficiency of our HVAC, seems totally logical to me.

        • Eryn says

          Mike J and Jason, thank you for the info! I have two furnaces and just had them checked today (semi-annual maintenance). The HVAC technician recommended that I may want to get a "dynamic air cleaner". Their cost to provide it and install it up front is $475 (x2 because I have two furnaces), although I may get a small discount because I am signed up with a maintenance plan with them. I've been trying to do some research. It sounds like this Dynamic Air Cleaner is actually different from the air cleaner you're talking about? Am I right? Or am I just falling for some more expensive option? We do have allergies in my family, and I'd like to address that by doing something more than the simple furnace filters (Yes, Jason - so annoying with the ratings! My Filtrete says "2200" which I think is about a MERV 12)... when I looked up Q&A on Dynamic Air Cleaners, it said this:

          "Dynamic Air Cleaners do not create charged particles that will cling to grounded surfaces in the home. Electronic air cleaners to date have worked by ionizing (positively charging) the particles in the air. They then try to capture them on negatively charged or grounded collection plates. This works fairly well at first, but as the plates load up with positive particles, they lose their attraction and the air cleaner loses
          its efficiency. The positively charged particles then will stick to any grounded (walls and ductwork) or charged (a TV screen) surface."

          (Incidentally, they do say that if you already have an electronic air cleaner in your house, they can retrofit them with this dynamic air cleaner.)

          Could you shed some light? I'd so appreciate it! Thanks!

  5. KM says

    For 1" thick filters above 24" there is a added charge,..a high added charges. If you need the larger filters go to You will have to pay a $5.95 shipping, but you can add as many 6 packs as you want and still only pay the same shipping. Also, at least once per year at a minimum, homeowners should clean the evaporator coils on your ac along with spraying down the compressor coils. Also, it is wise to drop a cup of bleach down your ac condensation line as it will keep bacteria and algae from clogging the line.

  6. Jack says

    Great post - I think you summarized the situation well. I have sort of a hybrid solution in that during the time I run the system the most I use the disposable filter that I can pitch and the rest of the time I have a set of reusable filters that can be hosed down and put back in place. My filters are easily accessible so that isn't an issue for me. Again, thanks for the effort and research.

  7. Dan says

    You're all wasting your money on replaceable filters! Purchase a $20 - $30 washable MERV 8 filter. To clean, simply run a sweeper over both sides to remove dust, hair, etc. then spray water through one side of the filter in the same direction as the air flow (indicated by arrows on edge label). Be sure to spray each cell (I think of it as an Excel spreadsheet spraying every row and then column of the filter). Lastly take your leaf blower and blow through one side of the filter in the same direction as the air flow to dry and remove any remaining small obstructions. The filter is now good as new!

    I've had excellent results with filters lasting 10+ years without any crap from the air or filter itself getting into the AC unit. Even though it's a 3 step cleaning process every month or two (depending on use and/or season) it is well worth the cost savings and filtered air that my family breathes.

    • says

      Dan - This is some great insight on washable filters. I always wondered if those worked as well as the paper based. That being said, for me personally, I'm sticking with paper - because I don't really like washing the filter each month. I agree that it would be cheaper, but I just don't like doing it. I do like having a reason to fire up my leaf blower though...

  8. longbeachyo says

    Very nice. Now you need to tackle the TV industry and their arbitrary "response time" ratings... Ready, set, GO!

  9. Gustavo says

    Jason, you have different sizes filters, are you using a cascading filtering system? I have but one filter - at the indoor coil - but I was wondering what effect it would be in the system if I added filters at the return registers.

  10. Paul says

    Here's another website with good prices. I have a 20 X 36 X 1 filter. I have been using True Blue, bought at Home Depot. It's the FPR 5 rating. HD has been the only place that carries my size (not even Lowe's carries that size). I looked at various websites and the prices for a MERV 8 were ridiculous. I found this site, and they have a generic MERV 8 for $4.83 and offer free shipping with a $99 purchase.

  11. says

    It's awesome to pay a visit this web site and reading the
    views of all mates regarding this article, while I am also zealous of getting

  12. Paul says

    Good blog man, your sentiments are probably universal. Although, I don't know why you are surprised that each company tries to muddy the waters by coming up with their own arbitrary standards to force you to buy their products (Apple, Dell, etc). Until we tell them by not buying their products unless they use an industry standard, they will continue to obfuscate (MERV, FPR, MPR) as long as they can.
    So keep on using your space to illuminate this kind of stupidity and help the rest of us see past the bu$$@#*t!

  13. Rina says

    Should the filter stick out at all or should it fit flush with the unit? I don't want to have to dig for it, but I want to ensure it is the ideal size to be the most efficient.

    • says

      Hi Rina - The air filter should be flush. Mine is the same way, a bit tricky to grab and pull out. I bought a cheap pair of pliers and I just leave them their right next to the air filter in my basement HVAC. - Jason

  14. Overzeetop says

    FYI - using a lower MERV filter will not damage your furnace. On the contrary, using a very high MERV may (though it's unlikely). A low MERV rating means that it does not pull as much dust out of the air, which means the filtration is less efficient. The damage to the furnace comes when you have too much resistance and the airflow over the coil is insufficient to remove the heat which can damage the modern, thing (and efficient) heat exchanger fins or insufficient to prevent icing of the fins in cooling periods.

    Higher MERV usually means higher resistance to airflow for the same filter type (exceptions, of course, exist). Don't fear a low MERV for HVAC damage, just realize that it will not filter as well as a higher rated filter.

    • says

      I 100% agree here on the higher merv. A bit higher is probably fine, but be careful if you decide to go all clean air crazy - you absolutely can damage your HVAC and it's VERY expensive. - Jason

    • AL says

      The main purpose of your HVAC system is to heat and cool your home, unless you have something exotic that is specifically built to clean your air. That said, if you want to clean your air, buy an air cleaning/purification system. Use low Merv (e.g. 4) filters for your HVAC. You'll get better heat and cool performance. This is the type of filter that ships with the unit when it was installed.

  15. David says

    So for years I've been buying HD's Honeywell FPR7 filter and always wondering if I should be getting the higher FPR9. Everyone in the family has allergies of one kind or another so I felt that I was maybe being a little cheap by going with the FPR7. So this last time I brought home an FPR9. After pulling off the wrapping I studied both the old FPR7 and the new FPR9 and, aside from the dirt in the old filter, I could see absolutely no difference between the two. Same cheap cardboard frame, same flimsy webbing. Is there really ANY difference between the two? I was really expecting some kind of numerical code on the frame that may have been different between the two filters. Nothing. Now I'm wondering if, perhaps, it's the same filter and just repackaged (with the outer wrapper) for a different price point. I have perused many of the earlier comments on this site and agree that I probably shouldn't be buying the filters through HD anyway - but I'm still curious.

    • Steve P says

      I was looking for the same thing and nada. If a mistake was made at the packaging facility no one would even know! Last filter I buy from Home Depot. Hopefully other places will have the pertinent info or some kind of identifier on the filter itself.

    • says

      Hey David - I'm by no means an "expert" on filters and I'm still pissed at HD for making life harder for everyone but I don't think they would deliberately lie with the packaging. There is a difference in the thickness of the weaving of the higher MERV filter.

      Now... for my personal opinion, which is backed by waaayy to many hours reading articles online - paying extra for the 9 versus the 7 will not noticeable reduce allergies. Of course everyone is different, and maybe for your family that would make a difference or "seam" to make a difference but to me there are a lot of other things you should do that will make a much bigger impact than the air filter. The whole point of the air filter is to protect your HVAC unit, not filter the air for breathing. The marketing for these air filters has just gone bonkers with this whole "health" angle.

      If you want to clean the air (for breathing sake) then buy a really good air cleaner! Like this one here. Good luck, allergies suck! - Jason

    • says

      Chico - Yes! This is exactly the kind of pricing shenanigans you have to watch out for and why I don't trust Home Depot (when it comes to filters). The links you list are not the same MERV filter rating. The HD version is much less effective filter lower. For me, I like MERV 8, you can get a box of MERV 8 filters (that's 12 in a box) for about $45 on Amazon (that's with shipping included). At home depot an equivalent box CAN'T BE FOUND! You can buy the next level up from MERV 8 which they call FPR 8 and it costs $96! Or you can buy the next level down, which I think is to flimsy for about $10 less.

      I know it's confusing, by that's my whole point - they're confusing on purpose. My advice, no matter where you buy your filters - only buy ones that rate using the national standard, which is MERV, do not buy FPR. Then compare price. You can't go wrong with Amazon. - Jason

  16. Cindy says

    Ok, yes I'm a woman, but because I'm the financial person in the family I have wanted a way to compare ratings and prices as well. Found your blog in my most recent search, but as I continued on in the quest to find a way to compare I found this handy chart: It doesn't solve all the questions but it's the only place I found that at least gives a good reference to start!

  17. Jason says

    There is some good information here, but I have to disagree with some of it. Yes, highly restrictive filters can be harmful, causing excessive motor wear and premature component failure. The bigger issue with airflow restriction is overheating of the furnace and insufficient primary and secondary air. However, the number one cause of failures for newer furnace equipment is components becoming so dirty that they fail, or, at least do not function as designed. As with everything in life, the technology applied to heating equipment continues to evolve. Why would you use a MERV 8-13 filter that only removes 2%-4% of the particles in the air when better! more efficient electronic air cleaners can remove upwards of 90%?. These days you can spend more than $10,000 on installing new furnace/ac equipment so the best way to protect your investment is to provide the best air quality possible. Cost is the biggest hurdle as EAC's can be anywhere from $600-$10000, but these components can greatly extend the life and efficiency of your equipment. I guess if you are happy with hardly filtering the air you breath at all, then just stick with the MERV 8 filters.

    • says

      Hi Jason - Interesting take on air filters. Do you have a link to what you mean by EACs? I can see how this might work in basement but what about my upstairs unit where the filters are in the ceiling - how would you hook up an EAC in there? $600-$1000 is a lot of money for better air? Wouldn't you agree? Which EACs unit do you have?

      - Jason

  18. El Toro Dave says

    My HVAC heater/blower/evap. unit is in my attached garage. It uses two "stacked" 1" filters. My HVAC guy says to use a cheaper (less efficient ?) filter to protect the top more efficient/costly filter and change the bottom one more frequently than the upper one if it still looks good. Seems this combo probably reduces resistance too.

    • says

      Hmmm.. interesting, I've never heard of the stacked air filters. Seems like a reasonable idea to me. The "efficiency" word is kind of tricky when talking about filters because HVACs can get starved for air if you get too efficient. This combo idea has merit to me. - Jason

  19. says

    Merv rating also relates to how it handles particles of different sizes. 8 is plenty to protect from dust that accumulates on the blower and coil while balancing with a low pressure drop.

    Higher is more about smaller stuff that might bother your breathing. But the air passes the filter many times in your home so even if it's only 5% effective at the small stuff it gets plenty of passes. You want to make sure the filter covers the whole area and is sealed well. Otherwise, it's Merv 0 allowing big dust particles to pass ( and even though it's cleaning your air and your lungs will thank you) dust will accumulate in the blower /ductwork / coil and degrade your efficiency.

    Better to have a Merv 3 with no gaps than a Merv 15 with small gaps. The pressure drop depends on how much filter area you have per cfm. If you can get a bigger filter, you can up you rating and not sacrifice performance. Deeper 4" filters have more surface area because of pleats and can hold a lot more dust (longer life).

    Make The filter deeper and bigger and raise the Merv and you would have cleaner air, a filter that could last a year, and higher efficiency cooling and heating. I work data center engineering where we are moving millions of cfm of outside air all the time. Whereas a lot if you guys are saying "I'm not an expert but... " I actually am an expert for what it's worth.

  20. Jerry B. says

    Just returned from Lowes's and Home Depot. Saw the arbitrary number FPR number at HD and some four digit MPR (micro particle rating) number. Neither of those numbers are the industry standard MERV rating, and I think the big box boys are just trying to confuse you with inferior product or attempt to justify their exorbitant prices.
    Off subject, let me give you another example of how these stores get to you. My 12 volt landscape lights were doing great, but I had a couple of them burn out. Replaced them with the big box store Phillips brand. These two bulbs kept burning out. Looked at the back of the box and they were rated for 300 hours. That's roughly two months' normal use this time of year. Found some on line for one twentieth the cost with twenty times the life span.

    • says

      Thank you Jerry. This is exactly what I'm talking about. Again, nothing against Home Depot, I love their store. But this policy tactic for air filters really bothers me. It makes me wonder about everything else in their store. What else do I not know? I don't have this mistrust with Amazon or Costco. - Jason

  21. DT says

    Got this info from the Nordic Air website:

    MERV / MPR / FPR
    13 / 2200-Black / 10-Blue
    12 / 1900-Navy / 9-Purple
    12 / 1500-Purple / 8-Purple
    11 / 1000-Red / 7-Red
    8 / 600-Light Blue / 5-Green

    However, MPR and FPR seem a little "fudgy" to me so I'd probably find MERV equivalent and bump up one notch just to be safe. Or just buy filters that have a MERV rating.
    As far as damaging the fan coil/air handler/furnace... you have to look at the rated pressure drop. Most manufacturers do not provide this information. When they do, it is often incomplete. For a pressure drop value to have any meaning it must be given in relation to filter thickness and FPM (air speed in feet per minute). In other words, for a given filter thickness, the pressure drop is X at Y FPM, expressed as in w.c., or inches water column.
    Flanders is very good for giving comprehensive tables, some give charts, some manufacturers spit out a figure with no relation to thickness or FPM.
    What FPM relates to your system is dependent on the system. Take tons x 400 to get CFM (air movement speed by volume). Now take the area of your filter (W x H) in inches and divide by 144. Now take CFM and divide it by (W x H / 144). This your effective FPM. If your air return was sized ideally, this should be 400 FPM, however a range from 300-500 CFM is acceptable. If you are outside this range you really need to get an HVAC specialist on the phone.
    Having this exact FPM number helps you to read resistance (pressure drop) charts given by some manufacturers. If the manufacturer only expresses pressure drop at 300 and 500 CFM then you should go off the 500 CFM value to be safe.
    Next, pull up the technical spec document for your furnace or air handler. It will give CFM values for different external static pressure drop values for the BTU unit you have. Find the external pressure drop value that relates to what you got off the manufacturer's website and find the max CFM at that value for your size unit. It should be equal or greater to tons x 400. Also, look through the rest of the tech document for any other stated restrictions on external or filter pressure drop values.
    In my case I have a 2.5 ton heat pump with a 30KBTU air handler and 16x20 return. This gives me an effective FPM of 450. (Why my installer sized the return this way I don't know.) The air handler tech document specifically advises against external static pressure drops of more than 0.40 in w.c. I find that the CFM on the 30KBTU air handler with an external pressure drop of 0.40 is 1028 CFM with the fan on High. That's good enough for me.
    So I look for a filter with a max pressure drop of 0.40, preferably less. I ended up going with the High-Capacity version of the Flanders 62RM11 MERV 11.

    I would probably be fine with MERV 8 except that my wife has major allergies. In addition I have also gotten dual UV lights in the air handler.
    Incidentally the silly little basic filter the installer put in was something on the order of MERV 4, IIRC.
    This isn't all of my air quality worries, though. To avoid unequal pressure in the house that would cause dirty outside air to get sucked in I'll need to leave our bedroom doors open at least a bit. Which is not a problem 98% of the time for us. To fix it so we can shut our doors would require the installation of jump vents which were not specified in the contract. I'll consider it later.
    Moral of the story: HVAC air quality and efficiency is a tricky business and even the best installers don't take time to really think through what it means for you and your home. With everything I've written there is still 2-3x more info that would be pertinent to the discussion.

    • says

      Uuuuhhhh... wow. Ton of info here. I think what you're saying is still Merv 8 is the best middle ground? But obviously lots of factors could change that. - Jason

      The other "rankings" only complicate an already confusing question - hence - I hate them with all of my will and power.

      • JJ says

        Now THAT'S what I call info! All I'm trying to do is get a 16x20x1 filter for a seven year old, basic Lennox 80 gas furnace, Model No. G40UH. (I didn't buy it. The energy efficiency sticker rates it a 78, just two points above "inefficiency" level. An "efficient" model is 90 to 96.)

        Went to Home Depot last week and paid $18 plus tax for a single Honeywell FPR 9. I don't ever remember the filters costing that much. Couldn't find the MERV rating of, course. Then yesterday I was at Costco and saw a three-pack of Filtrete 1900 for $40. If I'm reading DT's Nordic Air chart correctly, that means both the Honeywell FPR 9 and the Filtrete 1900 are MERV 12. That's fine as far as filtration goes, but what's a MERV 12 doing to the airflow of my crummy furnace? (I should add that the double-pane windows installed two winters ago had absolutely no effect on my heating bill. Maybe the windows weren't the real problem.) No cats, no allergies here, but the dust bunnies seems to reproduce like rabbits. :)

        Should I return the Honeywell to HD and go shopping for a MERV 8?

        • says

          Yo JJ- Merv 8 is my jam, it's certainly my recommendation for the right balance of cost and performance. Thanks for you input on your own air filter situation, this certainly helps everyone else who comes along and is reading this article. - Jason

  22. Michael says

    Good article, and good stuff from DT, 2/12/15.
    I use an Aprilaire 1210 media filter installed at the airhandler, with an (upgrade) 213 media kit, with no paper filters at the return air grills. It's a MERV 13, rated at 0.06"w.c. pressure drop at 600cfm. The media is a little pricey, typically $40-50 on line, with free shipping if you buy a couple. They're supposed to be good for a year. I monitor pressure drop across the filter with a digital manometer, and will replace the media as needed. I notice a huge difference in air quality with the MERV13, no longer waking up with a stuffy head - both wife and I have mild allergies. Equally important with MERV rating is careful sealing of all ductwork and airhandler cabinetry, especially on the return side, to prevent sucking in contaminants.

    • says

      uuuhhhh... wow. Michael, props on your technical knowledge on air filters, pressure measuring and all around bad assery. Anyone with allergies, hope this helps, chime in with what you use. - Jason

  23. Jim says

    Oddly, I found your site while looking for tips on finishing the basement in the home we just purchased. Our new home has an Aprilaire whole house filtration unit in it. It uses a truly monstrous accordion style filter that needs to be changed every 6-12 months. With our dogs, it will likely be closer to 6. I found these online at $28 apiece, so I ordered a 4 pack. Changing it is a bit of a process but in the end, I think it will be a healthier choice for me and my allergies.

    • says

      Ha, you never know where a good article on air filters will pop up. May have to check into a whole house filtration system, our two tiny "kittens" are now almost full grown cats and it's hair galore down in the basement. Might need a Roomba Robot too! - Jason

  24. Pucha says

    Hello Jason, thanks for the information and the same for all the others that have contributed!!!!! I agree with everything you say but in my experience I think that I will go with a Merv 11 (FPR Red 7 at Home Depot brand) or any other Merv 11 online, I find a cleaner environment inside the house. Not higher because then it will probably limit the A/C performance. I will try something next time I change filters: I have a HEPA filter vacuum and will try to clean the dirty side of the filter and see the results, in this way perhaps I could extend the filter life for one more month, multiply by 12 filters package means and extra year!!!!!! Will post in the future about my experience, thanks once more indeed!!!!!

    • says

      Hi Pucha - Yes, I can see that. It's certainly worth a test. I'm not as picky about air quality but I get it. Thanks for commenting, please do let us know your results. - Jason

  25. Brad says

    Hi Jason - I found your article here when I found myself in the same predicament. A few months ago we had a new A/C system installed, which came equipped with one of the huge 20 x 25 x 4 'whole system' filters. The installer mentioned it would last 'up to a year'; I was skeptical, and sure enough just a few months later I found it to be plenty clogged. (yep, we have cats and dogs) The filter was a Honeywell, with a MERV 11 rating. Off to Home Depot I went, finding the ubiquitous FPR numbers. They offered a 2 pack of 'FPR 8' filters for $40.00, or a single 'FPR 10' filter for $30.00. The 2 packs were sold out, and I needed it now, so I bought the FPR 10 one. When I opened it up back home, printed on the filter itself, not visible from the outside packaging, was 'MERV 12'. Hopefully this information will help someone else. You can bet I will now be checking out the various online filter vendors. Thanks again

  26. John says

    So--I guess I'm a bit confused. I understand the whole frustration with the additional rating system by home depot, but it does follow the MERV system pretty well. I totally agree with the fact that they are trying to get you to purchase more filter than you need, but if you look at the numbers, it appears like you only need their lowest (FPR 4-5) or green level to get to MERV 8.

    As far as cost goes--I purchase the Home Depot 3 pack of FPR 4(Green) which is equivalent to MERV 8.

    The cost is 7.74 for 3 filters, making each filter 2.58. I can't touch this price for anything online in a MERV 8.

    Am I missing something?

    • says

      Hi John - I understand your confusion. This is precisely the thought process the Home Depot marketing department hoped you would have. And listen, I love Home Depot, I shop there all the time, they are a great store.... except for air filters.

      MERV 8 is not the same as FPR 4-5 (Green at Home Depot) FPR 4 is a lower quality filter. I bought both a MERV 8 filter and a FPR 4 and you can tell just by looking at them that the 8 is a higher quality. I would love to be able to just buy a lower cost filter, I hate spending money on these things... but... ALL of the HVAC guys I've talked to and who've commented on this article have said - don't go lower than 8 or your risk damaging your HVAC.

      I visited the website you linked to; I think they are overly generalizing the effectiveness of the various levels. It is not accurate in my opinion, they do not align that perfectly.


      • AL says

        The longest lasting residential HVAC units I've serviced all run factory air filters (Marv 4) unless they are specifically designed as an air cleaning and purification system. If you want to clean your air without decreasing the life and performance of your HVAC system, get an air cleaning and purification system.

  27. OC_Carl says

    This off topic, but given your excellent information I wanted to point out a few presentation problems:
    Like the first sentence, "for you house". I guess you did not ask your wife to proof read?
    Also you quote "seam" above when I really think you meant to quote "seem" (Webster's Dictionary as reference)
    I note the first comment was dated June 29, 2013, yet your blog is dated December 1, 2014. Was this blog updated from a previous version? What, if anything changed?
    Of course this comment should not be posted.
    But I do find this a great blog. Glad it is still here.

    • says

      Hi OC_Carl. Always happy to accept and correct typo's and grammatical mistakes. Yes, this blog post gets updated often. I recheck pricing and the Home Depot filter product by actually going to Home Depot to take a look. So yes, some of the comments may be older than the post date.

      Glad you like the post, I hope it's been helpful. - Jason

  28. Michael a. Massetti says

    Jason; sorry for the late reply, thank you I did receive the link to the cost estimator.
    yep ; you are so correct on some choices to purchase item that can be bought on- line than at home creepo (lol). that's why I subscribed . I want to warm and cosy my basement . its also increases my homes value etc; however , with the proper information it can be awesome. It will be slow going ,however when done my basement will look great thanks to this site and you.
    Michael a. Massetti

  29. Dave says

    The previous owner of my house had the filter placed in the space after the blower, and there wasn't a designated spot for it - it was just wedged in there. The blower is in the garage, and the return, which is around 18x30, is by the front door. Should the filter actually be at the return?

    • says

      Hi Dave - It's hard for me to picture this setup your describing so let me know see if I can answer the question with a general guideline - you want to filter the air before it gets to the furnace / air handler. The filter is to keep the air clean before getting to the sensitive components of the HVAC NOT to clean the air on it's way out. Hope that helps! - Jason

  30. Larry says

    great to see folks taking an active interest in their home mechanicals. here's what i've run into more times than i care to think about. the filter opening was sized for a filter which is no longer available. can't get them anywhere, not even grainger sells them.

    so when dealing with old ductwork, which has been sized for an older unit, you don't really have a choice except to go one size larger on the dimension where the insert opening is. in my case, the opening width was cut so exact that the overhanging 1.5 inches provide a good seal. yep, very sticky getting the one inch filter to slide in.

    the system has remained very, very clean. and i know i'll invite critique for this, however i use 20 inch box fans as air cleaners with merv 8 filters behing tham. i have five that i run. (big house) and since then, my furnace filter replacement has gone to every four months.

    at my workplace, our air handling equipment is attached to our johnson controls metasys building control software, and the air handlers have manometers which alert us to increased pressure drop across the filters we use. we have never received the alert in the 8 years i've been there, and we use merv 8's, changed every four months. those units are fully cleaned per the filter change change schedule.

    a note-if your a/c condenser, usually outside, is running--don't aim your lawn mower discharge at it, and blow grass clippings all over the coil fins...and if the neighbor is in the habit of not caring..inspect it about once every two weeks. and if you're getting a new install-try to site this part of the system in the shade.

    great blog.

    • says

      Hey Larry - thanks for the input on the HVAC and Merv filters. I've heard from many people that MERV 8 is the best combo of filtration and value but it's good to hear from someone with some experience! - Jason

  31. Andrew says

    I can't find the proper size for mine: 14 1/2 X 27 X 5 and then there is another filter spot for 14 1/2 X 27 X 1. Any suggestions? I use to buy on home depot but can't buy in store and haven't been in stock online in months!

  32. says

    I was a little confused about FPR and MERV, I've been using the cheap see thru for under $1 filters for almost 40 years. After 18 years of great performance with Trane I went with a new Trane. I didn't want a lot of restriction so I opted for buying @ H.D. the FPR 4 the lowest FPR pleated filter I could fine. @ about $8 for 3 20"X25", I'm content with my choice, and appreciated the comparison of FPR and MERV .

  33. craig says

    The reason a higher MERV filter can damage the HVAC blower is because the blower is designed with a specific MERV and pressure drop in mind. Higher than spec MERV would mean more pressure drop, and would require a stronger blower motor.
    Therefore, if it were possible to upgrade the motor, then a higher MERV rated filter would be acceptable.
    There is one other factor to consider before increasing the pressure drop associated with a higher MERV filter: the filter seal must be good, otherwise the dust will pass around the filter.
    If the HVAC could be set up with a sufficiently strong motor and filter seal to support a higher MERV filter (e.g., MERV 13), then it seems like a very good place to do the filtering.
    I recently puchased an excellent HEPA 13 vacuum cleaner (Miele) and the difference dumbfounded me. Also other changes: stick to solid floors no carpet, no padded furniture, a lightweight bed frame that can be easily moved and clean, , airing out the matress on both sides when not in use.
    My dry mouth problem, sinus problem, body itching and acne problems all went away.

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