Reuben's Home Inspection Blog


The Dirt On Expensive Furnace Filters


Are super expensive furnace filters really worth the extra money?

Ultra Allergen FilterThe main job of a furnace filter is to keep big stuff from getting in to the furnace's heat exchanger or the air conditioner's air coil and clogging things up with dust, pet hair, and other big stuff.  They're not intended to purify the air you breathe.  Furnace filters protect equipment; not people.

Manufacturers of furnace filters would have you believe otherwise (big surprise).  The most expensive disposable filters that I commonly see are the Best 1" Air Filters made by 3M. These filters are marketed as being able to

"help attract and capture allergens from the air passing through the filter including mold spores, pollen, pet dander, dust, smoke, smog particles and particles that carry bacteria and viruses."

Sure.  I'll buy that.  I'm sure these filters do a great job of preventing all those things from passing through the filter. There is no claim made, even by 3M, to improve indoor air quality.  Up until recently, these filters were sold as "Ultra Allergen" filters, but they've recently changed their wording.  I don't know when this change happened, but I'm sure it was quite recent - you can still purchase "Ultra Allergen" filters on Amazon.

If you want to improve indoor air quality, try something else. Expensive furnace filters have been proven to have a very small effect on indoor air quality.  There is plenty of anecdotalevidence out there that says expensive filters will solve all of your indoor air quality problems, but I haven't been able to find a single study backing these claims.

The problem with expensive furnace filters is the amount of air flow that gets restricted when they get dirty.  As I mentioned in my blog about the importance of changing your furnace filter, reduced air flow can actually lead to premature failure of your furnace, besides costing you more in heating bills.  This can also lead to service calls on your furnace.  Furnaces come equipped with heat sensors that will shut the furnace down if the heat exchanger gets too hot, and the main cause of this is insufficient air flow.

StanleyAt my own house, I use a cheap pleated filter.  It's reinforced with steel wire on one side and will last for up to 90 days.  I have a German Shepherd (Stanley) who sheds like crazy, so I change my filter a little more often - about once every 60 days.  I don't like the super-cheap fiberglass filters because they seem to let too much stuff through, and I'm concerned that the air coil would get gunked up with all that dust that would still come through.

My recommendation is to skip those super-expensive furnace filters.  I think they're a waste of money.


Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 45 commentsReuben Saltzman • March 15 2011 05:47AM


Well that was a very clever headline. In general. I have not given that much thought to air filters. But you bring up some good points for consideration. Thanks for the post. Have a great sixty days!
Posted by Michael Kitsch (Coldwell Banker) over 7 years ago

Thank you for sharing the information. I do not know much about air filters and am glad home inspectors advice buyers about filters.

Posted by Gita Bantwal, REALTOR,ABR,CRS,SRES,GRI - Bucks County & Philadel (RE/MAX Centre Realtors) over 7 years ago

Thanks Reuben. We had shifted to the higher priced filters since we have a lab/retreiver mix- talk about fur flying! Your explaination make perfect sense. Sounds like we need to go back to the mid-priced filters & change them more often. Great post.

Posted by Bill Laundon (Apex Cary Insurance ) over 7 years ago

Good Mornig Reuben, your input on furnace filters is apperocated!  Thanks for posting it.

Posted by Dan Edward Phillips, Realtor and Broker/Owner (Dan Edward Phillips) over 7 years ago

This has been a topic of discussion in our home more than once, me con, Liz pro for the more expensive ones.

Posted by Liz and Bill Spear, RE/MAX Elite Warren County OH (Cincinnati/Dayton) (RE/MAX Elite 513.520.5305 over 7 years ago

Cheryl - thanks, I think that was my best post title yet :)

Gita - we do what we can.  I'm no expert on indoor air quality, but I've listened to a lot of experts talk about it.  

Bill - Did you notice any difference?  There are lots of testimonials from people that claim the filters make a big difference, but I suspect a lot of that is the placebo effect.  Try switching the filter without telling anyone in your family, and see if anyone notices ;)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Dan - thanks for reading.

Bill S - try my advice to Bill L.  Try switching the filter without telling Liz and see if she notices a difference.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Cheap or expensive, MOX NIX. 

If you don't clean or change them, they ain't gonna do much good and will harm your system.

Which is the best furnace filter??  THE ONE YOU USE!

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley,, MD & VA Homes and Real Estate) over 7 years ago

In my posts on this I say that the blower only exchanges the air in the house 3 or 4 times a day, certainly not enough to filter the air in the house.

There are two philosophies on filters!  Easy flow with less filtration or max filtration with less flow.  Oh, the horror, the horror...

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 7 years ago

What I want is a filter that will "filter" without putting extraordinary load on the motor that runs the dang unit. 

Filers are cheap.  Motors are not.

Posted by Lenn Harley, Real Estate Broker - Virginia & Maryland (Lenn Harley,, MD & VA Homes and Real Estate) over 7 years ago

Hi Reuben - Thanks for this really useful information. I went to hit Suggest, but see that it's already Featured! Congrats on that.

Posted by Judy Klem, Home Staging, Senior Move Management, Fairfield/New Haven counties (Transition Stage LLC) over 7 years ago

Hi Reuben, very good advice to the consumers and your clients.

Posted by Dale Ganfield over 7 years ago


Thanks to your earlier post on the topic, I thought to check my filter after lots of sanding work was done in the guest house on the property.  Yuck!  I'll even check the new one sooner after all that dust was generated.

Posted by Irene Kennedy Realtor® in Northwestern NJ (Weichert) over 7 years ago

Reuben....I am guilty of using the Ultra-Allergen air filters.  I have a daughter with allergies.  We have no pets but if I am so busy blogging I don't always get to dust!  And then, we are heading into pollen season (if it ever warms up). I have been using those to reduce the amount of dust & other allergens that get blown around when the heat or the a/c is on.  I never thought too much about air quality per se - just that stuff that is blowing around.  I change the filter every 3 months like clockwork. 

So, are you saying that I should not bother with the ultra allergen?  Just get the regular fitlers?  And, do I need to change it more often?  I was always told 3 months so that's what I have been doing.

Thanks for the information!  I would suggest but see it is already featured!

Posted by Christine Smith, Exclusive Buyer Agent & Attorney, Canton, MA (Buyers Brokers Only LLC - over 7 years ago

I have to get better with this and start changing filters more regularly !!!!!!!!!

Posted by Michael J. Perry, Lancaster, PA Relo Specialist (KW Elite ) over 7 years ago

Reuben, I had an electronic filtering system put in a couple of year ago. Did I waste my money?

Posted by Michael Setunsky, Your Commercial Real Estate Link to Northern VA over 7 years ago

I usually buy the mid range....I think even more importantly than the kind of filter is to make sure you check and change them as required....don't put one in and leave it there for months on end like some I have seen.

Posted by Dennis Duvernay Broker/Owner (Hillview Realty) over 7 years ago


Love this info.  We property manage a lot of high end homes.  We are constantly changing filters out to keep the systems running well.  Good advice as we can save some $$ on the type we buy. 


All the best, Michelle

Posted by Michelle Francis, Realtor, Buckhead Atlanta Homes for Sale & Lease (Tim Francis Realty LLC) over 7 years ago

Thank you for getting this out to us today.  It's appreciated!


Patricia/Seacoast NH & ME

Posted by Patricia Aulson, Realtor - Portsmouth NH Homes-Hampton NH Homes (BERKSHIRE HATHAWAY HOME SERVICES Verani Realty NH Real Estate ) over 7 years ago

Hi Reuben, I've used both and they all work as claimed but you have to increase the frequency of replacement.

The finer the filtering the faster it loads up, so the sooner it need s changing out.

You can extend their useful lifetime by using a shop vac on them, but that has its limits. 

Posted by Robert Butler, Montreal Home Inspector | Aspect Inspection (Aspect Inspection) over 7 years ago

This is a good post. I've been using the fiberglass filter but after reading this will probably change to the pleated filter.

Posted by Jody Moore (Blue Shirt Photography | SendOutCards) over 7 years ago

I had replacement filters for years then switched to one I Have to wash. Not sure if it is a better deal or not. 

Posted by Lizette Fitzpatrick, Lizette Realty, Lexington KY MLS - Kentucky Homes (Lizette Realty - Richmond KY) over 7 years ago

I am amazed at how many home owners I have encounter who didn't even realize they were supposed to change their filters at all!

Posted by Christine McInerney, The McInerney Team, Knoxville TN Homes For Sale (Great Life RE) over 7 years ago

thanks for this I am always telling my husband we should perhaps have the better ones as we have an expensive luxury home but I have taken it all on board.


Posted by Debra Hughes (Keller Williams Realty) over 7 years ago

Good morning, Reuben. Very interesting info. I had not realized that no company was specifically claiming that their expensive filters actually improved air quality. Thanks for the insight!

Posted by Bill Burchard, Broker, Realtor, Representing Buyers and Sellers (3B Realty: 951-347-3818, CA) over 7 years ago

My HVAC guy has told me the same thing. Save your money on the super extra filters.

Posted by Scott Petersen (Client First, Realtors - Canton, MI) over 7 years ago


Great advice. I have talked with HVAC techs on this. It seems that most say go with the higher flow rate for the performance of the system. I had an issue with my filters restricting the airflow enough to caused some major icing during the AC  usage. Once I put the cheaper filter in and more airflow it reduced this.

Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 7 years ago

Thanks for the advice. Reuben. More evidence that even high-end products don't replace actual work-change your filters often and don't worry about getting the fancy stuff.

Posted by Ilyce Glink, Best-selling author, award-winning TV/radio host. (Think Glink Media) over 7 years ago

Great advice...  I have often wondered about this very same thing!

Posted by Chris Alston, Silicon Valley, California (Chris Alston (Keller Williams Realty, Silicon Valley, California)) over 7 years ago

My furnace uses 2 filters (which I didn't realize for quite some time).  I always changed one and didn't even know there was another one on the back side.   Maybe other readers need to double check -- 2 filters or one?  When they go on sale at my hardware store, I stock up so I always have extras.....saves money and reminds me to replace them. I always thought the purpose of the filter was air quality and not furnace equipment protection.  Never too late to learn.

Thanks Reuben for the valuable information.

Posted by Jack Tenold, Conventional and Reverse (Caliber Home Loans, Inc. NMLS 15622) over 7 years ago

Reuben ~ That was certainly the best advice I have ever heard about filters ~ Cheap pleated reinforced with steel wire on one side ~ will check these out ~ Thanks for the dirt!!

Posted by Karen Baker, Professional Help with Rapid Responses... (Sunset Beach and Beyond Realty) over 7 years ago

A lot of pros and cons on filters but I am definitely for the ones that work vs the price and false promises.  Save the motor, keep your health in shape and change the filter often.  Good reminder for those who do not change the filter too often.

Posted by Barb Van Stensel over 7 years ago

Very interesting topic!  I knew to change them and I see enough filthy ones to know that's not exactly common practice in homes,  I usually go for the mid-range, good to know I'm not missing any extraordinary benefits from the more expensive ones

Posted by Diane McDermott, Charlotte NC Real Estate Market (Realtor®, GRI, Landis e2 Real Estate, LLC) over 7 years ago

Reuben, a 3-pack of pleated filters gets me through a years worth of HVAC activity.  Great points, and rarely, if ever, have I found the filters to be affecting flow upon their replacement.    

Posted by Kevin J. May, Serving the Treasure & Paradise Coasts of Florida (Florida Supreme Realty) over 7 years ago

I don't know, I just thru one out today that was pretty fuzzy. I've noticed that the house is dustier without a good filter. That's my stance & I'm sticking with it.

Posted by Lyn Sims, Schaumburg IL Real Estate (RE/MAX Suburban) over 7 years ago

Lenn - definitely, filters are only good if you remember to change 'em.  You say you're looking for a filter that won't put an extra load on the blower motor... I've heard about UV lights that can be installed in the ductwork.  I don't know much about 'em, but my dad had one installed at his own house.  

Jay - Three or four times a day?  That's sounds about right.  Not a way to clean your air.

Judy - thanks.

Dale - I've given this spiel many times during home inspections.  Now I'll have a link to give 'em.

Irene - good plan.  You might even want to turn your furnace off when heavy sanding is going on.

Christine - lots of people swear by the Ultra-Allergen filters.  If that's what you're using, I would change them more than every 90 days.  90 days is the longest you're ever supposed to get out of the filters; you'd be better off changing them more frequently.  Also, give the inexpensive pleated filters a try to see if you notice a difference.

Michael P - set a reminder on Outlook.

Michael S - No, you probably didn't waste your money on the electronic system.  They do a fine job of removing dust particulates, and you don't have to replace any filters.  They just take a little more work because you need to clean the pre-filters and the electronic cells.

Dennis - I completely agree.

Michelle - I'm glad I could help.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Patricia - thanks.

Robert - I once saw a guy in his garage with a big pile of furnace filters that he must have taken home from work.  He was blowing them all out with an air hose.  I took a photo of him doing this, but I can't remember where it is.  I'd rather just buy a new one :)

Jody - I don't have any problem with the fiberglass filters, but it's only a little more money for the pleated.

Lizette - I've heard nothing but bad stuff about those washable filters.  I'd go with the disposable.

Christine & Jennifer - me too :)

Debra - glad to help with the argument.

Bill - I was also surprised.  You really gotta read the wording carefully to realize this.

Scott - most HVAC guys I know say they love those super expensive furnace filters... because they create service calls!

Donald - I've seen that same thing happen to people many times.

Ilyce - that's about it.  

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Chris - thanks!

Jack - two filters?  That's quite unusual.  I've seen it before, but it's rare.

Frank & Karen - thanks, glad to help.

Barb - you got it.

Diane - the cheap pleated filters would be considered a mid-range.  It sounds like we're on the same page.

Kevin - you're pushing the limits, but then again, you probably have several months where you rarely need to run the blower on your ... furnace?

Lyn - I'll be looking for the lab reports on the indoor air quality for your house.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

I'm totally with you on this one. I have never owned or lived in a home with a furnace, but a filters a filter, whatever it filters. The finer the holes, the quicker it clogs. Those super filters also have a reputation for freezing up A/C coils just like you say, by restricting air flow.

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 7 years ago

I kinda forgot to talk about iced up AC coils; it's just been such a long time since I've even thought about AC...

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Interesting reading on your choice for a furnace filter.

I use a more restrictive filter and change it every 2-3 weeks.  I also add a spray coat of disinfectant.  I've been thinking about adding a UV light yet I'm concerned about degradation with dust. 

Do you have any experience with UV in the ducts?

Posted by Jim Mushinsky (Centsable Inspection) over 7 years ago

Hey Jim, I don't have any personal experience with those UV lights, but my dad had one installed at his own house, and he thinks it might help. 

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 7 years ago

Reuben, I think the biggest issue with these filters is two fold:  the amount of air that can get around them due to poor restraint and not changing them often enough.  If you take care of both of these issues the cost is not so much a factor.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 7 years ago

Good post, I find that changing a less expensive filter more often is more effective also.

Posted by Chris Smith, South Simcoe, Caledon, King, Orangeville Real Esta (Re/Max Chay Realty Inc., Brokerage) over 7 years ago

I agree, Reuben. A simple air filter is much healthier for your heating/cooling system! Beware of all the marketing that goes on!

Posted by Steve Stenros, CREIA MCI, ICC, ACI Home Inspector,San Diego (Poway,La Jolla,Del Mar,Mira Mesa,Carlsbad,Escondido,Temecula) over 7 years ago