4" vs. 1" Filter

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Old 05-31-20, 12:29 PM
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4" vs. 1" Filter

I hear that the recommended AC filter is a good 1" filter and change monthly. I have a 4" box and am considering building a 3" spacer to put in the filter box and use a 1" filter instead of my 4" filter. Comments?
 
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Old 05-31-20, 02:14 PM
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I guess, why not, what is it your trying to avoid or duplicate?
 
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Old 05-31-20, 03:18 PM
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If you use the 4" filters..... they don't need to be replaced as often as the 1" ones do.
 
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Old 05-31-20, 03:26 PM
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4” is superior to a 1” filter.
Airflow can be reduced with thinner filters and cause equipment problems if you use a high MERV rated filter.
 
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Old 05-31-20, 04:28 PM
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4” is superior to a 1” filter.
Maybe, maybe not. You cant assume just because the filter is deeper that its' better! Filers are rated on efficency but that is dependent on air circulation. A high efficient filter that sits unused is less efficient than a filter in constant use;

So goes the big issue, home HVAC systems run for minutes per hour, how are you going to filter out imputities when the system has limited run time!
 
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Old 05-31-20, 04:57 PM
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To be honest with you, the main purpose of the air filter within the hvac system is not to act as an air cleaner for the home. It’s to keep dust and debris out of the air handler.
Of course you can design it to do so, however the overwhelming majority are not.
The only way you can get constant filtration to maybe make a difference is to continuously run the blower, but a negative byproduct of that is it can raise the indoor humidity by re-evaporating moisture off the coil after the compressor shuts off.
The 1” high MERV filters that make claims of filtering out allergens and germs kill airflow tkk on the point the equipment performance can be affected, or even be damaged.
 
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Old 05-31-20, 10:50 PM
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or even be damaged
Well, maybe, any filter left in a furnace too long will eventually clog up with crud and lower its performance but to imply that the filter itself is going to cause problems is a bit of a reach.

Not any different than changing that air filter on your car engine, got to take some responsibility to change them when they get dirty!
 
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Old 06-01-20, 03:03 AM
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The only difference between a Merv 11 one inch and a 4 inch is the square inches of filtering material.

As the filter is used it starts to clog up since there is more filter area with a 4 inch you have to replace it less often.

I would also think that a new 4 inch would have less resistance to air flow than a one inch because the pleats are larger but I have never measured this so it is just an opinion.

So I do not know where you heard that a 1 inch is better than a 4 inch but I would disagree with this.
I have had both and the 4 inch does a better job but this is on different furnaces so it may not be due to just the filter.
 
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Old 06-01-20, 05:39 PM
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to imply that the filter itself is going to cause problems is a bit of a reach.
No it's not. Air filters can damage equipment. Coils can freeze up, motors run hot and furnaces will overheat.

Yes.... a clogged filter can cause the same problem but hopefully that is only a temporary issue..... not like running hi merv filters all the time.
 
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