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

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:
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?


How can doubling the thickness _reduce_ resistance?

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"dpb" wrote in message ...
james wrote:
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?


How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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Bob F wrote:
"dpb" wrote in message ...
james wrote:
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?

How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


?????

--
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On Oct 22, 12:46*pm, dpb wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


?????

--


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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In article
,
N8N wrote:

On Oct 22, 12:46*pm, dpb wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness reduce resistance?


It doubles the surface area.


?????

--


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


Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.
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Default is it always better to use a thicker filter in furnace?

On Oct 22, 2:26*pm, Smitty Two wrote:
In article
,





*N8N wrote:
On Oct 22, 12:46*pm, dpb wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness *reduce *resistance?


It doubles the surface area.


?????


--


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


Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.- Hide quoted text -

- Show quoted text -


/\/\/\/\ -- that's a 1" thick pleated filter

I can't do it with my keyboard, but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.


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DerbyDad03 wrote:
On Oct 22, 2:26 pm, Smitty Two wrote:
In article
,





N8N wrote:
On Oct 22, 12:46 pm, dpb wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness reduce resistance?
It doubles the surface area.
?????
--
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

Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.- Hide quoted text -

- Show quoted text -


/\/\/\/\ -- that's a 1" thick pleated filter

I can't do it with my keyboard, but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.


And twice the material in the same opening.

--
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On Wed, 22 Oct 2008 09:36:09 -0700, "Bob F"
wrote Re is it always better to use a thicker filter in furnace?:


"dpb" wrote in message ...
james wrote:
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?


How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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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On Oct 22, 2:56*pm, dpb wrote:
DerbyDad03 wrote:
On Oct 22, 2:26 pm, Smitty Two wrote:
In article
,


*N8N wrote:
On Oct 22, 12:46 pm, dpb wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness *reduce *resistance?
It doubles the surface area.
?????
--
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
Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.- Hide quoted text -


- Show quoted text -


/\/\/\/\ -- that's a 1" thick pleated filter


I can't do it with my keyboard, but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.


And twice the material in the same opening.

--- Hide quoted text -

- Show quoted text -


True. However, I've got the same amount of dust in my house with 1"
filter as with a 2". If I spread that dust over a twice the area, that
would reduce the resistance.

In other words, that blanket of dust after 3 months of use would be
half as thick, thus presenting less resistance.


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"Caesar Romano" wrote in message
...

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.


And 17 or more filters would reverse the airflow!


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Bob F wrote:

"dpb" wrote in message ...
james wrote:
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?


How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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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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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Learn more about Jesus
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..


"dpb" wrote in message ...
Bob F wrote:
How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


?????

--


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On Oct 22, 10:33*am, "james" wrote:
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?


Every filter is different, they are rated for cfm and filtering
ability. I have a 4" april air that has good flow and filtration, you
have to find a rating in cfm, first pass % efficency and probably
more to know what you are buying. There are 1-2 " junk and 1-2" very
good filters made. How it seals in the case is maybe as or more
important since unfiltered air just bypasses with a bad fit.
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Easier to go to Walmart, and look at pleated, accordian fold filters.

--
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Learn more about Jesus
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..


"Smitty Two" wrote in message
news In article
2c3003bb-42c5-4ec6-b6f2-

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


Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.




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/\ /\ /\ /\ -- that's a 2" thick pleated filter
/ \/ \/ \/

but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.



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The suggestion was to use a single 2" filter instead of a single 1" filter.

--
Christopher A. Young
Learn more about Jesus
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..


"Caesar Romano" wrote in message
...

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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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.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"Erma1ina" wrote in message
...

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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If the Three Stooges were still around this would make an excellent
topic for another story.

What is so hard to understand. If you put 10 pounds of crap in a 5
pound bag you're asking for trouble.

G.S.

On Wed, 22 Oct 2008 11:26:38 -0700, Smitty Two
wrote:

Is there room in that dunce chair for two of us, dpb? It don't make no
damn sense to me, either.


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james wrote:
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?


Most of the HVAC work me and my brother do is commercial.
Every new installation gets 2" pleated filters because
they simply work better. Homeowners can have large air
filters like Aprilaire Media Air Cleaners installed on
their furnace/air handlers. http://tinyurl.com/yd8tq3
Someone posted that they had a problem with Aprilaire
filter packs sealing so any installation should be
checked thoroughly. There are several different brands
of large air filters and you should pick one that has
media you can obtain from a local supplier.

TDD


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On Oct 22, 9:29*pm, The Daring Dufas
wrote:
james wrote:
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?


Most of the HVAC work me and my brother do is commercial.
Every new installation gets 2" pleated filters because
they simply work better. Homeowners can have large air
filters like Aprilaire Media Air Cleaners installed on
their furnace/air handlers.http://tinyurl.com/yd8tq3
Someone posted that they had a problem with Aprilaire
filter packs sealing so any installation should be
checked thoroughly. There are several different brands
of large air filters and you should pick one that has
media you can obtain from a local supplier.

TDD


Air Bear has a positive tight seal
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ransley wrote:
On Oct 22, 9:29 pm, The Daring Dufas
wrote:
james wrote:
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?

Most of the HVAC work me and my brother do is commercial.
Every new installation gets 2" pleated filters because
they simply work better. Homeowners can have large air
filters like Aprilaire Media Air Cleaners installed on
their furnace/air handlers.http://tinyurl.com/yd8tq3
Someone posted that they had a problem with Aprilaire
filter packs sealing so any installation should be
checked thoroughly. There are several different brands
of large air filters and you should pick one that has
media you can obtain from a local supplier.

TDD


Air Bear has a positive tight seal


Oh yea, I found Air Bear on The Internet.

http://www.youtube.com/watch?v=L-a607j2dOo

TDD
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In article
,
DerbyDad03 wrote:



/\/\/\/\ -- that's a 1" thick pleated filter

I can't do it with my keyboard, but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.


Yeah, that part I get. Reducing the resistance is the part I don't.
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In article ,
"Stormin Mormon" wrote:

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.
--


Indeed it does. No problem about that. How does that *reduce* resistance?
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In article ,
Erma1ina wrote:

Bob F wrote:

"dpb" wrote in message ...
james wrote:
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?

How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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.


THANK YOU!


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In article ,
"Stormin Mormon" wrote:

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.


Halving the air flow through each square foot, and doubling the square
feet, does not equate to more air flow, or to less restriction. You
better use one of your lifelines.
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On Thu, 23 Oct 2008 09:39:35 -0700, Smitty Two
wrote:

In article ,
Erma1ina wrote:

Bob F wrote:

"dpb" wrote in message ...
james wrote:
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?

How can doubling the thickness _reduce_ resistance?

It doubles the surface area.


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.


THANK YOU!

I don't think so. Imagine a 1 foot x 1 foot duct. Now imagine a it
has a 1 foot by 1 foot filter in it. Now take a second case of the
same duct, but you have a 1 foot by 2 foot filter... same material
but double the area. If you put it in that same 1 x1 duct by putting
it in at a angle (60 degrees from perpendicular), air flow will be
better. You have double the cross section because you have
essentially created one big pleat. If you made a filter by
zig-zagging that 1 x 2 filter into a 1 x 1 holder, you have what the
OP was asking about.
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In article ,
greenpjs wrote:

On Thu, 23 Oct 2008 09:39:35 -0700, Smitty Two
wrote:

In article ,
Erma1ina wrote:

Bob F wrote:

"dpb" wrote in message ...
james wrote:
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?

How can doubling the thickness _reduce_ resistance?

It doubles the surface area.

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.


THANK YOU!

I don't think so. Imagine a 1 foot x 1 foot duct. Now imagine a it
has a 1 foot by 1 foot filter in it. Now take a second case of the
same duct, but you have a 1 foot by 2 foot filter... same material
but double the area. If you put it in that same 1 x1 duct by putting
it in at a angle (60 degrees from perpendicular), air flow will be
better.


So a lot of you keep saying. So far no one has offered an explanation of
the claim, and so far, I don't believe it. You all keep talking about
surface area as though you believe I'm having trouble with junior high
arithmetic.

The part I'm having trouble with is the completely unjustified and
unsubstantiated claim that doubling surface area doubles (or improves by
any factor) air flow, given the same cross-sectional area of duct.

You have double the cross section because you have
essentially created one big pleat. If you made a filter by
zig-zagging that 1 x 2 filter into a 1 x 1 holder, you have what the
OP was asking about.

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Smitty Two wrote:
....
The part I'm having trouble with is the completely unjustified and
unsubstantiated claim that doubling surface area doubles (or improves by
any factor) air flow, given the same cross-sectional area of duct.

....
I think the problem is folks aren't looking at the whole picture.
Assuming a fixed media fractional area for flow, doubling the total area
does indeed double the open area. If that were all, it would be an
improvement. Unfortunately, what they're leaving out is that the
structural material doubles as well.

Hence, I think as you -- initially there may be little _added_ pressure
drop but the only potential real advantage may be that of the loading as
somebody mentioned could, possibly, extend lifetime somewhat.

I've not done a full dynamics analysis at all, but I can't see any other
major effect not covered by those very basic geometrical arguments.

I did send off a request for data from a pleated filter manufacturer who
published some pressure drop data for their 1" filters and also make 2",
4" and 5" filters of the same type for comparative data. If they
respond, I'll post their answer.

A moderate search found no published comparative data of value, only
single numbers and much uninstructive babble as here.

--
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Smitty Two writes:

/\/\/\/\ -- that's a 1" thick pleated filter


I can't do it with my keyboard, but extend those pleats to 2" and
decrease the angle so each 2" pleat is just as wide as a 1" pleat, and
you've got twice the surface area.


Yeah, that part I get. Reducing the resistance is the part I don't.


The filter resistance per CFM per unit area remains the same, but you
now have twice the area of filter for the air to pass through. So the
CFM per unit area is reduced to half, and that reduces the pressure
drop.

A single 2" thick pleated filter is almost equivalent to two 1" thick
pleated filters in parallel (side by side, so half the air goes through
each).

Dave


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Smitty Two writes:

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.


Halving the air flow through each square foot, and doubling the square
feet, does not equate to more air flow, or to less restriction. You
better use one of your lifelines.


It's the same amount of total air flow. A reasonable measure of
restriction is pressure drop across the filter, and with half the air
flow per unit area, the pressure drop will be less.

How do you measure restriction, such that it would remain the same with
half the flow per unit area?

Dave
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Bob F wrote:

"dpb" wrote in message ...
james wrote:
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?


How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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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Smitty Two writes:

The part I'm having trouble with is the completely unjustified and
unsubstantiated claim that doubling surface area doubles (or improves by
any factor) air flow, given the same cross-sectional area of duct.


I haven't seen anyone claim the airflow would double. They have claimed
that doubling the filter area reduces pressure drop across the filter;
do you disagree with this?

Now, with a typical fan, reducing the pressure drop across the filter
slightly increases the pressure at the fan inlet, which will slightly
increase airflow. Not double, certainly, but more than zero.

Dave
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dpb wrote:

Smitty Two wrote:
...
The part I'm having trouble with is the completely unjustified and
unsubstantiated claim that doubling surface area doubles (or improves by
any factor) air flow, given the same cross-sectional area of duct.

...
I think the problem is folks aren't looking at the whole picture.
Assuming a fixed media fractional area for flow, doubling the total area
does indeed double the open area. If that were all, it would be an
improvement. Unfortunately, what they're leaving out is that the
structural material doubles as well.

Hence, I think as you -- initially there may be little _added_ pressure
drop but the only potential real advantage may be that of the loading as
somebody mentioned could, possibly, extend lifetime somewhat.

I've not done a full dynamics analysis at all, but I can't see any other
major effect not covered by those very basic geometrical arguments.

I did send off a request for data from a pleated filter manufacturer who
published some pressure drop data for their 1" filters and also make 2",
4" and 5" filters of the same type for comparative data. If they
respond, I'll post their answer.

A moderate search found no published comparative data of value, only
single numbers and much uninstructive babble as here.

--


Ya don't need "a full dynamics analysis" Do a freaking "thought
experiment" -- would you DECREASE or INCREASE air resistance by adding
filter after filter after filter etc across a duct ???? Of course you'd
INCREASE air resistence. Geesh people!
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flow divided by surface area. Divide by a larger number, to get a smaller
result.

--
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Learn more about Jesus
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..


"Smitty Two" wrote in message
news In article ,
"Stormin Mormon" wrote:

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.
--


Indeed it does. No problem about that. How does that *reduce* resistance?




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Erma1ina wrote:
....
... would you DECREASE or INCREASE air resistance by adding
filter after filter after filter etc across a duct ???? Of course you'd
INCREASE air resistence. Geesh people!


That's in series, agreed it would add almost linearly. That's not the
geometry under consideration here.

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Erma1ina wrote:
Bob F wrote:
"dpb" wrote in message ...
james wrote:
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?
How can doubling the thickness _reduce_ resistance?

It doubles the surface area.


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


There ya' go...right. I was concentrating on the areas knowing at best
it could stay same.

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On Oct 23, 3:52*pm, dpb wrote:
Erma1ina wrote:
Bob F wrote:
"dpb" wrote in ...
james wrote:
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?
How can doubling the thickness _reduce_ resistance?
It doubles the surface area.


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


There ya' go...right. *I was concentrating on the areas knowing at best
it could stay same.

--- Hide quoted text -

- Show quoted text -


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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Smitty Two wrote:

The part I'm having trouble with is the completely unjustified and
unsubstantiated claim that doubling surface area doubles (or improves by
any factor) air flow, given the same cross-sectional area of duct.


Sounds like you are envisioning a fiberglass filter, not the fan-fold
paper ones.

If you have a fan-fold one that has 1" thick folds then we will
arbitrarily say it has 2000 tiny holes in it (although it really has
more, obviously). Now if we make the pleats 2" thick we now have twice
as many holes in it, allowing twice as much air to pass thru it.

The outside dimensions stay the same, but the thickness of the filter
paper pleats (surface area) is doubled.
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"Caesar Romano" wrote in message
...
On Wed, 22 Oct 2008 09:36:09 -0700, "Bob F"
wrote Re is it always better to use a thicker filter in furnace?:


"dpb" wrote in message ...
james wrote:
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?

How can doubling the thickness _reduce_ resistance?


It doubles the surface area.


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.


Parallel. Exactly. The thicker filter is like two thinner ones side-by-side.


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