is it always better to use a thicker filter in furnace?

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My furnace was installed with a 16x20x1 pleated filter.
It looks like there is enough space to fit a 16x20x2 filter. This should last longer and reduce air resistance.
Is there any reason not to?
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james wrote:

How can doubling the thickness _reduce_ resistance?
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It doubles the surface area.
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Bob F wrote:

?????
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He did specify pleated. If you can find a 2" thick filter with a single layer of media, he is correct, the surface of the media would be approximately double that of the thinner filter, assuming the same number of pleats and that both filters have the pleat creases at the very outside of the filter.
nate
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Accordian fold, pleated filters. Look a bit like this, from the side:
V^V^V^V^V^V^V^V^V^V^V^V
So, the double thickness does provide more surface area.
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wrote Re Re: is it always better to use a thicker filter in furnace?:

So if you could rig 4 filters it would reduce the resistance more? And if you could put 8 or 16 filters you could reduce the resistance to almost zero.
I don't think so, unless you rig the filters in parallel.
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And 17 or more filters would reverse the airflow!
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The suggestion was to use a single 2" filter instead of a single 1" filter.
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Parallel. Exactly. The thicker filter is like two thinner ones side-by-side.
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wrote Re Re: is it always better to use a thicker filter in furnace?:

No, a thicker filter is like to thinner ones in series, one behind the other.
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Caesar Romano wrote:

Incorrect when the thickness is achieved by larger pleats. The actual filter *material* is the same. Bigger pleats in a thicker filter "container" means more area and less resistance.
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wrote in message

That's it.
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Bob F wrote:
...

There's double the additional structural material too...I'm still not convinced the dP goes down at all, it just may not go up much...
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Bob F wrote:

It's the CROSS SECTIONAL area that is important in fluid dynamics. Doubling the amount of material in that CROSS SECTIONAL area will RESTRICT the flow.
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With a PLEATED filter, DOUBLING the thickness increases the SURFACE AREA by about DOUBLE. So, you're actually DOUBLING the SURFACE AREA of the filter, which effectively HALVES the air flow through each SQUARE FOOT of filter material. Thus, PERMITS mroe air flow with LESS restriction.
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Bob F wrote:

Keeping the CROSS SECTIONAL area (duct size) constant while increasing the area (what you've called "SURFACE AREA")of filter material in contact with the fluid (i.e., AIR) moving through the duct increases the air resistance (in this case, the VISCOUS drag). QED
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Erma1ina wrote:

There ya' go...right. I was concentrating on the areas knowing at best it could stay same.
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I was the one that brought up the issue of loading.
Would you agree or disagree that spreading the same amount of dust over twice the surface area would "improve" the air flow over time - by that I mean it would flatten the "degradation of air flow" curve over the life of the filter. Not an actual increase in air flow, but a stronger flow for a longer time due to less restriction.
That's a legitimate question on my part - I'm not trying to convince you of anything, 'cuz i I don't know the answer. It just seems (to me) that the system ought to act that way.
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I was the one that brought up the issue of loading.
Would you agree or disagree that spreading the same amount of dust over twice the surface area would "improve" the air flow over time - by that I mean it would flatten the "degradation of air flow" curve over the life of the filter. Not an actual increase in air flow, but a stronger flow for a longer time due to less restriction.
That's a legitimate question on my part - I'm not trying to convince you of anything, 'cuz i I don't know the answer. It just seems (to me) that the system ought to act that way.
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It would do that, and lessen the drop across the brand new filter also.
If you look at the "holes per area" analogy, there are twice as many holes for air to flow through, and twice as many holes to collect the same amount of dust, so they plug more slowly.
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