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Fiberglass vs. pleated furnace filters

Posted by ljbrandt (My Page) on
Tue, May 4, 10 at 23:33

I've been doing ALOT of reading and research on this subject and can't find a definitive impartial opinion on which filter to use.
My situation : 2 year old Goodman 95% furnace and a/c unit. No allergies or excess dust buildup in the house...I just want the air handler to run as efficiently as possible with the least restrictive air flow, but don't want to lose mechanical efficiency by having dust build-up on the coils.
Will a basic el cheapo fiberglass filter changed every month be adequate in preventing dust buildup inside the unit? Whats your opinion? thanks!

P.S. as far as air filtration goes for pollen/dust etcIll be using a 20" box fan with a 20x20 pleated air filter attached :=)


Follow-Up Postings:

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RE: Fiberglass vs. pleated furnace filters

The fiberglass filters will stop small rocks, but that's about all. On the other hand, a lot of HVAC pros warn against using the 3M Filtrete brand pleated filters, claiming that they are so restrictive that they damage the air handler blower.

I settled for a happy medium, pleated filters that are not as restrictive as the 3M units, but are much better at trapping dust than any fiberglass unit. Home Depot and Lowes carry them.


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RE: Fiberglass vs. pleated furnace filters

fiberglass filters are next to worthless for dust.


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RE: Fiberglass vs. pleated furnace filters

So I take it that you believe the fiberglass filters don't really protect the internal workings of a furnace/AC from anything smaller than a bug?


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RE: Fiberglass vs. pleated furnace filters

If you have a standard size, MERV7 and MERV8 efficiency filters will work just fine. If you have a custom size, Pleated MERV8's are also available in a new 'reusable' format.


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RE: Fiberglass vs. pleated furnace filters

I use a Honeywell 4" MERV10 pleated filter FC40R1078 which has a lip and fits into many return ducts designed for standard 1" filters. I'm getting a full year's use out of them in So. Louisiana, for about $4/mo. Much less restrictive than the 3M filters, and they're sturdy enough that they don't make crinkling noises when the blower kicks on.


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RE: Fiberglass vs. pleated furnace filters

I found the perfect remedy years ago. I cover the fibreglass filter with the black filter material they use on window AC units. The fibreglass one provides the support needed and the black filter does a superb job of filtering. Haven't had to clean a coil yet, after 15 years. The black filter will set you back about $1. Now go do it.


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RE: Fiberglass vs. pleated furnace filters

creek_side..........whats the brand you are referring too?.............thx


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RE: Fiberglass vs. pleated furnace filters

Flanders NaturalAire.


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RE: Fiberglass vs. pleated furnace filters

I am asking about using a 3M pleated dust reduction filter. After buying and installing this filter ..nine days later our furnaces started acting up. We replaced three sequincers. Finally the they checked our filter ...only to be told that the pleated filter should not be used on our furnace. That we should use the fiberglass filter. The pleated filter was restricting to much air flow.. We changed and everything is working properly now


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RE: Fiberglass vs. pleated furnace filters

The fact the filter is pleated does not cause excessive restriction. The pleating increases the surface area which is an attempt to make it less restrictive.

The 3M filtrete filters are known to be restrictive. The Naturalaire filters are pleated and not as restrictive. The fiberglass filters don't do a very good job. I would not add additional filtering the the fiberglass filter without knowing how much added restriction is being added.


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RE: Fiberglass vs. pleated furnace filters

I use the Flanders filters, too. Buy them in a 3 pack at Home Depot.

They say they last for 3 months, but I leave my air handler fan running 24x7x365 (cleans the air, helps balance temperatures) so I replace them monthly.

For some years I used the fiberglass filters. They would stop some dust, but I think it was just luck.

I've noticed my house is significantly less dusty now that I'm using the Flanders filters.

I have, however, had a problem with the Flanders filters.
My system uses 20x20 filters, and that isn't a nominal measurement, that is an absolute.

If the filters are even a tiny bit oversized, they jam and I can't get them into the filter box.

Whenever I buy filters I have to measure them very carefully.


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RE: Fiberglass vs. pleated furnace filters

FIBERGLASS FILTERS ARE ALMOST WORTHLESS.HVAC PEOPLE RECOMMEND THEM BECAUSE OF LOW AIR RESISTANCE.PLEATED FILTERS ARE MUCH BETTER BUT STAY AWAY FROM ANYTHING WITH A MERV RATING HIGHER THAN 8. THEY ARE TOO AIR RESTRICTIVE AND CAN CAUSE PROBLEMS WITH A/C COILS ICING UP OR HEAT EXCHANGERS BURNING UP. MAKE SURE THE PLEATED FILTERS YOU BUY HAVE AT LEAST 15 PLEATS PER FOOT. CHANGE PLEATED FILTERS EVERY 3 MONTHS OR SOONER IF YOU SMOKE OR HAVE PETS OR HAVE AN UNUSUALLY DIRTY ENVIRONMENT. I HIGHLY RECOMMEND AAF "PERFECT PLEAT" MERV 7 OR MERV 8 PLEATED FILTERS.


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RE: Fiberglass vs. pleated furnace filters

I use a washable electrostatic filter - seems to allow decent airflow, has saved me a fortune on the expensive disposables. Worked well with my dog in the house.


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RE: Fiberglass vs. pleated furnace filters

I have a deep filter tray with tabs for 1" filters or with the tabs folded up a 4" slides down in. 20x25x4" 6-8 merv pleated is what I run. If a person can run a 4" filter its unbelievable about the amount of actual filter media and surface area for air to flow in comparison to a 1" filter.

Like everyone else said... very high merv ratings cause very high restriction and a little dirt/dust really plugs them fast in comparison. I have seen 1400merv filters which is crazy. I have sealed my duct system and used brush on mastic but I know it is still not sealed perfect enough to justify a 1400 filter.

If the filter(s) are not right at the furnace/air handler and are behind the return vent putting a high merv on these systems pull even more air through unsealed nooks and crannies and in some systems it is gaping holes.


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RE: Fiberglass vs. pleated furnace filters

Some of the filterete filters don't really have that much air resistance. The problem appears when you get their micro allergen reduction series and above. Filterete's dust reduction and also their dust and pollen reduction have pretty low air resistance , so you should be fine with filterete. Fiberglass filters are worthless. They can't even filter salt. It's sad. (Don't try it when the filter is inside the system)


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RE: Fiberglass vs. pleated furnace filters

plain and simple fiberglass filters are just above worthless. The black filter media cloth over a fiberglass makes a secondary filter that has decent filtration but poor surface area and as dust starts to build up the air flow will drop like a rock.

My 4" thick filters have 12 FEET of filter media on a 20x25x4"

Click the link.. Surface area is key to any filter system if you really want it to perform.

Here is a link that might be useful: Here is a 4


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RE: Fiberglass vs. pleated furnace filters

I have replaced many a blower, sold many a furnace because of the 3M filters. 3M is trying to keep HVAC service techs in business. Seriously, pleated filters, change every 30-60 days.I highly recommend an electrostatic air cleaner. There is no filter, and you clean it every 6 months in the tub or with a hose.Gets out 98% of what harms you.


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RE: Fiberglass vs. pleated furnace filters

Hi guys I want to share with you this great site. Just click to the link right here. In this site you can find everything you need for electrostatic furnace filters. Go in it and get the information you need. Hope I was helpfull :) Thank me later!

Here is a link that might be useful: http://www.healthyhomefilterco.com/


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