Filter MERV


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Old 08-20-10, 04:54 PM
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Filter MERV

Is there any site that shows MERV numbers (I think thats the term) for filters by brand? I know most of you Pros say a MERV 9 or so?

My wife won a free filter which arrived today...but it's one of the super filtration (allergens, pollen, dander, etc) type...and I just know it will really restrict the flow.

We don't use them normally...but if I use it during window open season (maybe a month) will it be an issue?
 
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Old 08-20-10, 05:05 PM
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rule of thumb Merv 5 filter or less require 200 sq inches of return filter face area per ton of cooling. What tonnage do you have and what size return filter? Not sure if there is a site that lists all the filters. It sounds like the wife has some emotional attachment to this filter so tread carefully cuz I bet there is NO AC in the dog house.
 
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Old 08-20-10, 05:19 PM
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Lol....thanks FM.....no..she could care less other than the fact she won it. If i said I used it last month and threw it away she'd never know.

It's a 20x25 return..packaged unit on the roof...think it's 3 ton? Maybe 3.5?

It works just fine...I use 1 step above cheap filters most times....ducts and grills are pretty clean for an old system.

Just seems like the fact that MERV is important to those in the know...the companies would make it a big deal and print it on the package.
 
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Old 08-25-10, 10:36 AM
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on a 3 ton you do not have room to fudge on return airflow with a 20 x 25 sized filter so stick with the free flowing filters.
 
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Old 10-08-10, 12:53 PM
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The 3M Filtrete site is terrible about giving MERV in a convenient chart but here is a list of their filters and if you look in the description it will give a MERV rating

3M Filtrete HVAC Filters

I know this isn't exactly what you are looking for but here is a MERV rating chart that will tell you what MERV rating does what as far as filtration goes. Doesn't list individual products though.
 
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Old 10-08-10, 01:00 PM
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Thanks John...the names are slightly different for the CA site, but that looks like more info than what I found.

I think the freebie filter might get used for about 2 weeks before I throw it away.

Oh...and Welcome to the Forum!
 
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Old 10-08-10, 01:53 PM
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Thanks for the welcome!

I am trying out one of the 3M allergen filters in my home HVAC (can't remember which one at the moment). I wish I had a particle counter or something like that to measure the effectiveness but those things are spendy!
 
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Old 10-08-10, 06:21 PM
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The 3M filters are hard on your equipment, I even talk my customer out of them and go with the basic 3 pack Home Depot's green label. (step up from the fiberglass)
 
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Old 10-21-10, 10:51 AM
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From Consumer Reports magazine, October 2010

On page 5, under LETTERS:

A repaiman told me that high-quality furnace filters impede airflow, making the furnace work harder. Is that true? Paul Seguin Venice, FL

They don't make a furnace work harder, just longer. High-efficiency filters are designed to trap smaller particles, so it's more difficult for air to get through them. In our airflow-resistance tests of whole-house air filters, also known as furnace filters, we found that some are better than others. Follow manufacturers' recommended replacement intervals or replace high-efficiency filters after finishing tasks that disperse fine particles, such as sanding.

I hope it helps.

P.S. The September 2010 issue of CR evaluated air purifiers, as well as DIY air filters and pro-installed filter systems.
 
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Old 10-21-10, 12:20 PM
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True, the furnace is going to run longer since the air flow is cut down, and the blower will have to pull harder to get the air flow over those high end air filter.
 
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Old 10-21-10, 02:00 PM
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Well...

According to Consumer Reports (September 2010 issue): the Lennox Healthy Climate HC16, which is installed by a professional, has the same Airflow Resistance than a
3M Filtrete Elite Allergen 2200 MPR filter. Actually, as far as air flow is concerned: the 3M Flitrete Elite Allergen 2200MPR, 1900 MPR, Micro Allergen 1000 MPR and the 600 MPR, all scored Very Good. The same thing than the Healthy Climate HC16 installed by a professional.

The only one that scored higher, iow, Excellent as far as Air Flow is concerned, is the Carrier EZ Flex Filter Cabinet. Though it was quite inferior to the Lennox in terms of Smoke Removal.

P.S. I use 3M 1700 filters and last week, as my Lennox G61 MPV gas furnace was working, I pulled out the filter and what I noticed is that the motor slowed down a little. Overall, I didn't feel the extra load of using 3M filters added that much of a burden to the electric motor. My logic about using such filters, is that I prefer to get the dust inside the filter, than inside the evaporator coil of the A/C inside the furnace. Quite difficult to clean...
 
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Old 10-21-10, 03:39 PM
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Nostradamus the problem is that a system needs to be sized for this extra static pressure. You would be better off going with a space guard than a 3m filter.
 
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Old 10-21-10, 04:03 PM
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Don't forget..CR consistantly reports that BEHR interior(?) paint is one of the best...but Pro's consistantly say they'd never want to use it. They also rated our vacuum as a best buy..but its a total PITA to actually use it.

No Expert...but I think standard furnace filters are designed to filter the air for the HVAC equipment...not the people.

I like CR for some things...but not everything...they test in laboratories...not the real world.
 
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Old 10-22-10, 08:18 AM
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I agre with you in regards to CR. They are not perfect. And I disagree with some of their conclusions, but I have to admit that they have more money and time than I have to test and evaluate products.

Regarding the fliters and the furnace, I should mention that I set my thermostat so that the furnace blower NEVER works at full speed. Mine is a variable speed two- stage furnace and it always operates at the lowest speed. IOW, the electric motor has a lot of room to spin faster and still be at a fraction of its capacity.

I'm no engineer, nor HVAC specialist, but with the limited understanding I have of the laws of physics, if the motor spins at 30% capacity instead of 25%, I'm not exercising excessive demand on it. Maybe I'm wrong, who knows?

Nostradamus has been wrong before
 
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Old 10-27-10, 04:37 PM
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A good link to read about filters and such.

Your Furnace Filter | CMHC
 
 

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