# Is it worth it to get an expensive furnace filter?



## Karlhungus

What do you guys think? What do you do? Is it worth is to get a more expensive furnace filter or just buy the cheapest one?


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## OnlyMyOpinion

Advise we were given was to buy cheap and replace monthly during heating season. In some cases the 'really good' filters actually restrict air flow and heating efficiency.


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## cainvest

My 2 cents after running both types of filters, buy the cheaper ones. I got a pack of higher rated ones on a really good sale but I'll be going back to cheaper ones again.


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## jamesbe

Friend and HVAC sales for 22 years told me to get the cheap ones but get the ones that look like cotton not the fiberglass ones. They are about the same price but work better and change them monthly


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## 6811

jamesbe said:


> Friend and HVAC sales for 22 years told me to get the cheap ones but get the ones that look like cotton not the fiberglass ones. They are about the same price but work better and change them monthly


+1


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## Mortgage u/w

Same here....I get cheap ones and replace every 1-2 mths. 
I never understood how a filter can "last" longer. The more dirt it filters, the more it continues to trap, no? Or do the expensive ones have an invisible auto-clean feature I never knew about?!?!


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## cainvest

Mortgage u/w said:


> I never understood how a filter can "last" longer. The more dirt it filters, the more it continues to trap, no? Or do the expensive ones have an invisible auto-clean feature I never knew about?!?!


I think the idea of lasting longer, not one I agree with mind you, is the more expensive ones have more surface area due to more pleats. My furnace is cleaned each year so I see how much gets by the filter, and for both the cheaper/expensive filters, its very, very little.


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## Retired Peasant

We bought a permanent filter for our last furnace, and our current one came with a permanent filter. We clean it every 1-2 months (just spray it with a garden hose). Works great.


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## OhGreatGuru

The old fiberglass filters (cheapest) won't stop pollen or small dust particles. You should at least be looking for one of the many choices in a pleated-fabric filter. Most manufacturers use a MERV rating system, with ratings from ~8 to 13. 3M continues to use a Micro Particle Rating (MPR) System, that uses much larger numbers (~600 to ~1900 or higher). You can find web sites that give approximate equivalents between the 2 systems.

Most of the material I read suggests that, unless you have severe pollen allergies, it's not cost-effective to go higher than MERV 8. I think most pleated-fabric filters currently available all achieve MERV 8, and have a passive electrostatic fabric. The incremental cost for higher rated filters is huge.

3M (Filtrete) literature suggests a higher rating if you need to filter pet dander or mold spores.


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## RBull

^good info.


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## Terminator

I've debated this issue for a while in my house. After about a year of paying for premium quality filters and getting tired of literally throwing money away, I decided to do away with replaceable filters altogether and installed an electrostatic furnace filter. It was the best decision I could have made! The house stays cleaner than any replaceable filter I used, and after crunching the numbers, the electronic unit will have paid for its self within a couple years when compared to buying replaceable filters.


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## Brian K

I tried the 3M Filtrete filters that Big Box stores sell and have Mike Holmes' picture on them. I noticed that the air temperature at the air vents was about 5 degrees warmer than a less expensive, but still a decent, pleated type air filter - a Dust Stop I think. So to me that meant there was a considerable restriction in air flow through the furnace and therefore a hotter heat exchanger which, in my opinion, could make the heat exchanger fail earlier. I've also been to a few neighbours houses when they didn't get any heat. Turned out the problem were dirty filters and the furnace was shutting down on high temperature in the heat exchanger. So to me the restrictive type that filter out 'everything' are very close to a plugged filter and probably won't last as long as one that filters decently and will last longer. Furnaces need to breathe properly to be efficient.

I also tried a Tox Box insertion type electrostatic filter. Seemed to work just OK - but the replacement filter elements were kind of pricey and we didn't really notice a cleaner house so I went back to the dust stop - 2 for ~ $10 with a MERV of about 8 I think and I'm happy with how they function and how dirty they are after a month or 2 - they are doing their job. The blue fiberglass ones don't stop much but eventually they do plug up too.


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## My Own Advisor

I was told to buy 3M (Filtrete) to filter pet dander.

If you don't have pets simply buy the cheap ones replace every month.


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## agent99

RBull said:


> ^good info.


Yes it is. Life of filter is not the only reason to buy the expensive filters. It is their ability to actually filter out the dust and other nasties that is important. Even more important when you have pets or you are a smoker. 

One other thing. If you don't get the dust out of the air, it will settle out in your ducts when the air flow stops or slows. That gives you the opportunity of hiring one of those duct cleaning outfits that keep calling 

I am frugal, but still buy at least merv 8, sometimes 12. We have a manometer across the filter that shows if the filter is in need of changing. If interested, this is a good write-up on subject.


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## Brian K

A great article on furnace efficiencies related to air flow and a great little gizmo I might NEED! And he says don't get a more restrictive filter than you NEED because you will waste energy. I don't buy the cheap fiberglass filters - I get the MERV 8 class rather than the super duper Ultra High Hepa because I don't want to restrict the furnaces' ability to breathe. Buying a highly restrictive filter will really mean you have to change it more often too because the smaller particles will plug it up faster. It also doesn't mean you should change it less either although you won't want to change it because the Filtrete's are sooo $$. You don't want to forget to change the filter either. That eventually causes the heat exchanger to overheat and shutdown on high temperature and this could eventually cause a failure of the heat exchanger. 2 friends have had that happen.


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## OhGreatGuru

My Own Advisor said:


> I was told to buy 3M (Filtrete) to filter pet dander. ...


3M Filtrete doesn't tell you anything if you don't also specify their MPR (Micro Particle Performance Rating). 3M makes these with several ratings from MPR 600 (~MERV 8) to MPR 2200 (~MERV 12+). They're all called "Filtrete", which is simply 3M's brand name.


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## OhGreatGuru

As BrianK points out, pressure drop across the filter may become an issue as the "quality" rating goes up, because the filter material is less permeable to air flow. Consequently if you need high-performance filters you may find it necessary/advisable to go to the 4" deep filters. This requires modifying your air return if it is not already sized for them.


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## Brian K

Yes - too bad they don't standardize on the filtering ratings. I guess to confuse and limit comparison shopping. When (and rarely) I buy the 3M ones, I get the lower MPR rating. I think the last one I got was a 600 - and they're cheaper than the 3M 'Super Duper filter everything out' 1200+ filters.
Those 4" deep filters look interesting - but only for needy filtering requirements due to the added cost of a tin basher to make it fit. Occasionally there are sales on and I take advantage of that too.


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## davidjones

*Regarding Electrostatic Air filter*

This is a very nice decision on your part. Earlier I was also using standard fiber glass air filters, but I was also exhausted in keep changing it after 2 to 3 months. One day I was just sitting in my office and I came through one article titled How To Choose the Right Furnace Filter For Better Indoor Air Quality also having mentioned their website http://unitedfilter.com/index.php/default/blog/choose-right-furnace-filter-best-indoor-air-quality/. It really provided me the best to do knowledge on the subject. So I decided to go for HEPA filter and it is really very powerful in relation to disposable filters.


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## Brian K

I agree that the cheapy fiberglass filters are probably just to keep the furnace components happy and don't do much to keep dust out of the air we breathe. As discussed in the article by United Filter, they recommend that you get 'a professional to retrofit your furnace'. I'm assuming that this means more than just sliding in a HEPA to replace the lower MERV filters and involves more than making a slot to accommodate a different size filter frame. I'm assuming but that sounds like someone should come in to verify furnace ari flows. I did try a high MERV rating filter and found that the air temperature at the heating vents in the house rose by about 5 degrees. To me, this means that the heat exchanger is getting hotter than it should. That reduces the efficiency of the furnace and since the heat exchanger is getting hotter, it may crack faster than it normally would. Heat exchangers are designed for a differential temperature which would require a minimum air flow. This makes we wonder if using a filter that restricts air flow too much will void the furnace manufacturers warranty on the heat exchanger. However it could be that the new highly efficient furnaces with modulating gas valves take this heat exchanger temperature difference into account and control gas to allow maximum efficiency. 

I agree however that for a few dollars, you should strive for the cleanest possible air, after all who wants to breathe dust but I also don't want to stress the furnace by not letting it breathe properly and overheat. I've seen filters left too long and they get plugged up and restrict air flow - much like a highly restrictive filter - and that causes the furnace to cycle the heat on and off because it shuts down on high heat exchanger temperature. It's a balancing act I guess with tradeoffs.


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## technotemp

*yes it is*

yes its worth.. they have good quality with good material, furnace give great performance..


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## carverman

Brian K said:


> Yes - too bad they don't standardize on the filtering ratings. I guess to confuse and limit comparison shopping. When (and rarely) I buy the 3M ones, I get the lower MPR rating. I think the last one I got was a 600 - and they're cheaper than the 3M 'Super Duper filter everything out' 1200+ filters.
> Those 4" deep filters look interesting - but only for needy filtering requirements due to the added cost of a tin basher to make it fit. Occasionally there are sales on and I take advantage of that too.


I go for the cheapest pleated filters on sale usually at CTC. Filters get dirty, even if you don't smoke. There is enough dust in household air even if the ducts are cleaned regularly every year and these days at the prices they charge ($250+), you have to wonder if they have discovered a gold mine with furnace ducts. 

From the point of frugality, the duct cleaning costs now push it to the point of what is more important? Clean air
with less expensive filters, or more expensive filters and spending the money on those vs duct cleaning done about every two seasons.

its a tradeoff...a pack of pleated filters ( Garrison) at $9.99, and changing them every month, especially during the heating season or paying a plenum fabricator for an expensive job in your home to measure and install the larger opening cold air return duct replacement accomodating the 16 x 25 x 5 inch ($42), 
or the 16 x 25 x 4 inch ($30) special filters (MERV 8), to replace the older style 1 inch thick filters.

In the end, unless you have a lot of pet dander and allergies or a smoker, how essential is it to have an expensive filter that requires the existing duct work to be modified at a $250 to $350 labour/materials expense,
or maybe just change the less expensive pleated ones more often.


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## Mortgage u/w

I think the majority agree that the expensive filters are just as effective as the less expensive ones. Its important that the distinction is made between what a 'cheap' and 'premium' filter is - they are both pleated and cotton-like. The 'cheap' filter does not refer to the fiberglass ones as those have a different use.

What's important is that they are changed frequently and according to usage. 

The thickness of the filter is not much of issue either. Whether its X1, X2, X4....its the amount of pleats that matter. The more pleats you have, the more surface coverage you have in order to trap dirt. The X4 does not necessarily have more pleats so keep an eye on that - I noticed the brand I buy will have more pleats on the X2 vs the X4. The X4 will have deeper pleats but since there are less of them, I have to conclude that the total surface coverage is equal to the X2, which costs me $10.98 for a 20x20.

I am not convinced the 3M filters are capable to trapping smaller contaminates. If true, then the air flow will be greatly restricted. Either way, its not a good thing. Don't forget, the furnace chamber is not a tightly sealed unit and can have many leaks, ultimately bypassing the filter all together.

Lastly, getting your ducts cleaned is a scam. If your filter is changed regularly and you vacuum the registers and return openings, you will not have excessive dust rolling in your duct-work. All the cleaning does is provide a clean sheet of metal for a new layer of dust to settle on. Dust can not accumulate to the point you can knit a sweater with it since the constant air flow prevents that


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## Koogie

Mortgage u/w said:


> Lastly, getting your ducts cleaned is a scam. If your filter is changed regularly and you vacuum the registers and return openings, you will not have excessive dust rolling in your duct-work. All the cleaning does is provide a clean sheet of metal for a new layer of dust to settle on. Dust can not accumulate to the point you can knit a sweater with it since the constant air flow prevents that


Guess you haven't bought a house lately ? We had the ducts cleaned in the house we bought last year. Probably haven't been cleaned in donkeys years. You could have knit a mannequin out of the cat hair and furballs that came out into the pump truck. No way we could have vacuumed that out ourselves from the registers and gotten into all the long runs and elbows. To think we would have been breathing that in..... yeech.
Our hvac guy says every 3 - 5 years is fine, depending on whether you smoke, have renos done, keep the windows open all the time, etc..

We are just in the process of replacing our furnace and a/c (we knew they were old when we bought and screwed the sellers down on the price a commensurate amount). Having read this thread I think we will give up on the 4" or 5" filter option on the new unit and just buy better quality 1" filters and replace them more often.


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## 319905

Most of the dust in our place ends up in either the dustpan, dust cloth, or the vacuum cleaner ... well ok, some may end up under a carpet now and then, just temporary :courage:. Decent vacuum filters are worth it, my opinion. I use washable advertised as electrostatic filters on the furnace(s) which I hose down now and then. As to wood working, dusty handyman stuff I do my best to clean up after myself as I go. How the heck do you guys get so much dust etc. in the duct work (air passes through the duct work before it gets to the filter)? I had a furnace repair problem a few years ago, the guy said he'd never seen such a clean furnace and duct coming into it.


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## Mortgage u/w

Koogie said:


> Guess you haven't bought a house lately ? We had the ducts cleaned in the house we bought last year. Probably haven't been cleaned in donkeys years. You could have knit a mannequin out of the cat hair and furballs that came out into the pump truck. No way we could have vacuumed that out ourselves from the registers and gotten into all the long runs and elbows. To think we would have been breathing that in..... yeech.
> Our hvac guy says every 3 - 5 years is fine, depending on whether you smoke, have renos done, keep the windows open all the time, etc.


Aside the fact if I bought a house lately or not, my current furnace duct-work is 17 years old. Never got it cleaned and there is nor has ever been any sheep fur in it. Thin layer of dust on the surface - yes. But wiping that layer only makes room for a new one as soon as the furnace is turned back on. 

If you just recently bought your house and found as much dust as you say in your ducts, then the previous owner did not maintain his furnace. And by maintain, I mean changing the filter. There is no reason other than a poorly maintained furnace that the ducts will get that dirty. A word of advice since you are changing your furnace; make sure to tell you're HVAC guy to properly seal all the leaks around the furnace and duct work as far as possible since I am certain your return air is bypassing the filter chamber. Pass you hand around the corners and any small opening and see how much air you feel. That's all air that is not being filtered.

Choosing the more expensive filters is your prerogative. Just ensure that your air is not restricted because of it.


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## OhGreatGuru

Mortgage u/w said:


> ...
> 
> The thickness of the filter is not much of issue either. Whether its X1, X2, X4....its the amount of pleats that matter. The more pleats you have, the more surface coverage you have in order to trap dirt. The X4 does not necessarily have more pleats so keep an eye on that - I noticed the brand I buy will have more pleats on the X2 vs the X4. The X4 will have deeper pleats but since there are less of them, I have to conclude that the total surface coverage is equal to the X2, which costs me $10.98 for a 20x20.
> ...


Where the thickness matters is in the resistance to air flow. As the filter "quality" goes up, it becomes more resistant to the air movement, reducing circulation and increasing the heat exchanger temperature. Changing to 4" deep pleated filter compensates for this by increasing the area of the filter media in the same rectangular duct space. The rate of air flow per sq.in. through the filter is lower, resulting in lower pressure drop across the filter.


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## agent99

The results below are from some independent tests done on a variety of filters.
This article is also a useful guide: 16x25x1 Furnace Filter - Buying Guide

We have two filters on our heating system 20x20 and 20x25. I bought a supply of 1" Merv 8 filters from a Canadian firm.
(United Filter - Furnace Filters | HVAC & Air Conditioner Filters | United Filter) also available on Amazon with free shipping: United Filter 16x25x1 MERV 11 Replacement Pleated Furnace Air Filter (Actual Size 15-1/2 x 24-1/2 x 3/4) , Pack of 12: Amazon.ca: Home & Kitchen


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## Rusty O'Toole

I live in an old farm house built about 1860 and it is rather dusty. So, I use a coarse filter in the furnace and made my own air filter by duct taping a HEPA furnace filter onto a box fan. This is 95% as effective as a HEPA filter for a tiny fraction of the price. And, I can easily see when it needs changing.


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