Commercial/Industrial HVAC filters, aka Bag Filters, are widely
available, and are no more expensive to purchase than a 20x20x4" filter
(BTW Honeywell makes 4" filters to fit standard return air grilles).


These filters come in 4 standard frame sizes, 12x24, 20x20, 20x24, and
24x24. They need ALOT of room behind the filter face as the media is
10 to 37 inches deep.

The filter media is 0.15 to 0.25 inches thick. Look at your pleated
filter, how thick is the material in the pleats?? Thin!! Much
thinner than this.

Filter media is then 10 to 120 square feet in size!!! a typical
residential pleated furnace filter 20x24 in size has about 6 sq ft of
filter in it.

They come in a variety of filter ratings from a number of different
manufacturers. I have seen Purolator on several web sites. Merv
ratings climb from 7 to 15. MERV15 on the Purolator models as is the
case with all fitlers with this rating will capture 95% of the 1 micron
and larger particles in the air, and the Purolator Defiant and Serva-Pak
models will capture 80% of the 0.3 micron particles. This is almost HEPA
ratings (99.97% of 0.3micron particles and up), but at a MUCH lower
costs. A HEPA filter sized to treat your whole HVAC will cost you
roughly $2800 to purchase and install. The filter costs about $300 when
you replace it.

You need the assistance of an HVAC pro to make an adapter for this in
your return air plenum, and to select a model that will not place undue
burden on your HVAC fan. This last point is very important as HVAC
fans are not really designed to pull air thru a filter any more dense
than MERV 11, and most of them work MUCH better if they have a MERV 7 or
less filter in them. This is an important point, as the
filter fitted by the manufacturer is there SOLELY to protect the
EQUIPMENT, not to protect YOU! You can find models of the 95% filter
bag that have initial pressure drops roughly the same as a Filtrete
UltraAllergan. Unlike the Filtrete which may need to be changed every
2-3months, this filter will not need to be changed any more often than
once or twice a year!!

$40 once or twice a year vs $19 or so at least 4 perhaps 6 times a year
AND you capture ENORMOUSLY more dirt, dust, pollen, mold. Your house
stays MUCH cleaner.

HEPA will do a better job at filtering, but it costs way more to acquire
and install and the annual filter replacement is MUCH more expensive too.

powder coat pocke filters are the same sort of filter, they are cheaper
about 32$ for the 20x20 filter.

Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.

Empressess #124457


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Robert Gammon wrote:
Commercial/Industrial HVAC filters, aka Bag Filters, are widely
available, and are no more expensive to purchase than a 20x20x4" filter
(BTW Honeywell makes 4" filters to fit standard return air grilles).


These filters come in 4 standard frame sizes, 12x24, 20x20, 20x24, and
24x24. They need ALOT of room behind the filter face as the media is
10 to 37 inches deep.

The filter media is 0.15 to 0.25 inches thick. Look at your pleated
filter, how thick is the material in the pleats?? Thin!! Much
thinner than this.

Filter media is then 10 to 120 square feet in size!!! a typical
residential pleated furnace filter 20x24 in size has about 6 sq ft of
filter in it.

They come in a variety of filter ratings from a number of different
manufacturers. I have seen Purolator on several web sites. Merv
ratings climb from 7 to 15. MERV15 on the Purolator models as is the
case with all fitlers with this rating will capture 95% of the 1 micron
and larger particles in the air, and the Purolator Defiant and Serva-Pak
models will capture 80% of the 0.3 micron particles. This is almost HEPA
ratings (99.97% of 0.3micron particles and up), but at a MUCH lower
costs. A HEPA filter sized to treat your whole HVAC will cost you
roughly $2800 to purchase and install. The filter costs about $300 when
you replace it.

You need the assistance of an HVAC pro to make an adapter for this in
your return air plenum, and to select a model that will not place undue
burden on your HVAC fan. This last point is very important as HVAC
fans are not really designed to pull air thru a filter any more dense
than MERV 11, and most of them work MUCH better if they have a MERV 7 or
less filter in them. This is an important point, as the
filter fitted by the manufacturer is there SOLELY to protect the
EQUIPMENT, not to protect YOU! You can find models of the 95% filter
bag that have initial pressure drops roughly the same as a Filtrete
UltraAllergan. Unlike the Filtrete which may need to be changed every
2-3months, this filter will not need to be changed any more often than
once or twice a year!!

$40 once or twice a year vs $19 or so at least 4 perhaps 6 times a year
AND you capture ENORMOUSLY more dirt, dust, pollen, mold. Your house
stays MUCH cleaner.

HEPA will do a better job at filtering, but it costs way more to acquire
and install and the annual filter replacement is MUCH more expensive too.

powder coat pocket filters are the same sort of filter, they are
cheaper about 32$ for the 20x20 filter.

Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.

Empressess #124457


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Robert Gammon wrote:
Commercial/Industrial HVAC filters, aka Bag Filters, are widely
available, and are no more expensive to purchase than a 20x20x4" filter
(BTW Honeywell makes 4" filters to fit standard return air grilles).


These filters come in 4 standard frame sizes, 12x24, 20x20, 20x24, and
24x24. They need ALOT of room behind the filter face as the media is
10 to 37 inches deep.

The filter media is 0.15 to 0.25 inches thick. Look at your pleated
filter, how thick is the material in the pleats?? Thin!! Much
thinner than this.

Filter media is then 10 to 120 square feet in size!!! a typical
residential pleated furnace filter 20x24 in size has about 6 sq ft of
filter in it.

They come in a variety of filter ratings from a number of different
manufacturers. I have seen Purolator on several web sites. Merv
ratings climb from 7 to 15. MERV15 on the Purolator models as is the
case with all fitlers with this rating will capture 95% of the 1 micron
and larger particles in the air, and the Purolator Defiant and Serva-Pak
models will capture 80% of the 0.3 micron particles. This is almost HEPA
ratings (99.97% of 0.3micron particles and up), but at a MUCH lower
costs. A HEPA filter sized to treat your whole HVAC will cost you
roughly $2800 to purchase and install. The filter costs about $300 when
you replace it.

You need the assistance of an HVAC pro to make an adapter for this in
your return air plenum, and to select a model that will not place undue
burden on your HVAC fan. This last point is very important as HVAC
fans are not really designed to pull air thru a filter any more dense
than MERV 11, and most of them work MUCH better if they have a MERV 7 or
less filter in them. This is an important point, as the
filter fitted by the manufacturer is there SOLELY to protect the
EQUIPMENT, not to protect YOU! You can find models of the 95% filter
bag that have initial pressure drops roughly the same as a Filtrete
UltraAllergan. Unlike the Filtrete which may need to be changed every
2-3months, this filter will not need to be changed any more often than
once or twice a year!!

$40 once or twice a year vs $19 or so at least 4 perhaps 6 times a year
AND you capture ENORMOUSLY more dirt, dust, pollen, mold. Your house
stays MUCH cleaner.

HEPA will do a better job at filtering, but it costs way more to acquire
and install and the annual filter replacement is MUCH more expensive too.

wrote:
powder coat pocket filters are the same sort of filter, they are
cheaper about 32$ for the 20x20 filter.

Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.

Empressess #124457


The HEPA filter I was discussing puts a ZERO pressure drop on your HVAC
system as the one I described has its OWN 1HP ECM2 fan inside and it can
tie to the same ECM2 terminals in your air handler so that it runs at
the SAME speed as your furnace.

However, continuous filtration, 24x7 is recommended for our health and
cleanliness, so a remote control or a dial setting on the unit running
in bypass mode at lower speed will work better.


I focus on the 24x24 size as it is better matched to my proposed new AC
system needs than the 20x20

However, for comparison, a 20x20x12 6 pocket filter in the 95% MERV15
filter rating goes for about $28

And a 20x20x6 pleated filter, MERV11 costs about $22,will have to be
changed MORE often as it holds less filter material, and it does not
filter as well as a MERV 15 filter does.

The chief advantage of the filter you mention, if I properly understand
what sort of filter you are referencing, is that the media is rigid and
can tolerate any flow rate, down to zero CFM.


Yes,a HVAC pro is needed to select the proper size and proper pressure
drop for YOUR installation. In a new construction project,you have lots
of freedom. Retro fit may be difficult to impossible.

However. I could adapt a 20x24x19 8 pocket filter to my 20x25 return air
grill filter frame with little effort. 1/2 inch wide flanges can be
attached to the vertical risers to seal to the back of the filter. This
filter has a pressure drop across it LOWER than almost ALL MERV11
filters. It has over 40 sq ft of filter media in it.

Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.

If the filter is, say, 3" thick and had many, many pleats then the extra
area can compensate for the extra resistance of the HEPA filter medium.

To me, that's the way to go. Rather than a high maintenance electrostatic
filter which, typically, requires 6" of space in the direction of flow, get
a pleated HEPA filter that fits in the same space.

John Gilmer wrote:
Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.


If the filter is, say, 3" thick and had many, many pleats then the extra
area can compensate for the extra resistance of the HEPA filter medium.

To me, that's the way to go. Rather than a high maintenance electrostatic
filter which, typically, requires 6" of space in the direction of flow, get
a pleated HEPA filter that fits in the same space.



The issue with HEPA filters that the poster complained about is that in
order to get the 99.97% entrapment of 0.3 micron particles and larger
takes large amount of fan power. Furnace fans cannot do this by
themselves. To move 1500 CFM (typical flow number for 4 ton AC units)
through a typical HEPA filter requires almost 1HP of fan power. Air
handler fans are woefully inadequate to this task as a typical air
handler fan only has a tiny budget left for filter resistance.i.e. MERV7
OVERLOADS THE FAN!!!

www.pureairsystems.com sells whole house HEPA filters that do not load
the air handler fan as they have an internal fan that blows at the same
CFM rating of the air handler .

The only advantage that a 4" or 6"pleated filter has over a 1"or 2"
pleated filter is a longer lifetime before they start to really bog down
the air handler fan.

One of these days people will start to realize that the furnace filter
is there to protect the equipment, not the occupants.

When you want to protect the occupants, the HP rating of the air handler
fan must increase to compensate, OR we add a fan on the other side of
the filter (as the pureairsystems folks have done) to PUSH air thru the
filter, reducing the load on the air handler.

Some manufacturers of heat pumps are starting to recognize the issue and
now offer motor upgrades on some models that doubles the HP rating and
gives the fan the power needed for MERV 11 and MERV 12 filters to be used.

Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.


If the filter is, say, 3" thick and had many, many pleats then the extra
area can compensate for the extra resistance of the HEPA filter medium.

To me, that's the way to go. Rather than a high maintenance electrostatic
filter which, typically, requires 6" of space in the direction of flow, get
a pleated HEPA filter that fits in the same space.



The issue with HEPA filters that the poster complained about is that in
order to get the 99.97% entrapment of 0.3 micron particles and larger
takes large amount of fan power. Furnace fans cannot do this by
themselves. To move 1500 CFM (typical flow number for 4 ton AC units)
through a typical HEPA filter requires almost 1HP of fan power. Air
handler fans are woefully inadequate to this task as a typical air
handler fan only has a tiny budget left for filter resistance.i.e. MERV7
OVERLOADS THE FAN!!!

Shouldn't you be able counteract this by increasing the area of the
filter?

Robert Gammon wrote:

The HEPA filter I was discussing puts a ZERO pressure drop on your HVAC
system as the one I described has its OWN 1HP ECM2 fan inside...

A hideous waste of energy. Use a 2 watt Envirosept filter instead.

Nick

Robert Gammon writes:

You need the assistance of an HVAC pro ...

You need help with your amathophobia.

Goedjn wrote:
Hepa filters put a huge strain on a blower as the pores are so small,
never do this one without an experts advice on capacity.


If the filter is, say, 3" thick and had many, many pleats then the extra
area can compensate for the extra resistance of the HEPA filter medium.

To me, that's the way to go. Rather than a high maintenance electrostatic
filter which, typically, requires 6" of space in the direction of flow, get
a pleated HEPA filter that fits in the same space.




The issue with HEPA filters that the poster complained about is that in
order to get the 99.97% entrapment of 0.3 micron particles and larger
takes large amount of fan power. Furnace fans cannot do this by
themselves. To move 1500 CFM (typical flow number for 4 ton AC units)
through a typical HEPA filter requires almost 1HP of fan power. Air
handler fans are woefully inadequate to this task as a typical air
handler fan only has a tiny budget left for filter resistance.i.e. MERV7
OVERLOADS THE FAN!!!


Shouldn't you be able counteract this by increasing the area of the
filter?

To some degree, yes. That is why pleated filters get so much attention,
as they increase the surface area of the filter dramatically. Have you
noticed that the 1" UltraAllergen filters from 3M have DRAMATICALLY
increased the number of pleats?

You can increase the size of the filter say by going from 20x20 to
20x25, more filter area. Change filter media to get higher levels of
filtration (MERV goes up), or change nothing and the load on the air
handler fan drops.

You can increase the number of pleats in the filter, again more filter
area. Change filter media to get higher levels of filtration (MERV
increases), or do nothing and the load on the fan drops.

You can increase the total depth of the pleats, going from 1"to 4",again
lots more filter area. Change filter media to get higher levels of
filtration (MERV increases), or do nothing and load on the fan drops.

With each of these steps, we increase the total filter area. If the
media stays constant, say MERV7, then the total dust holding capacity of
the filter increases, we don't have to change it as often. But if the
filter media changes, and we get a higher MERV value, the life of the
filter drops, as it traps more dust faster.

To get HEPA level filtration at the flow rates needed to handle your
WHOLE house, i.e. 1200CFM or 2000CFM, the depth of the filter increases
to 12 inches or more, filter size increases to 24x24 or more, filter
media area increases to 185sq ft or more, and the type of media
changes. In most big HEPA filters, the air flows thru 12 inches of
filter media.

In our household MERV 7 pleated media, the filter depth for airflow is
under 0.1 inch (thickness of the material in the pleat).

To push air thru 120 times thicker media, thru media that has higher
density, requires lots of fan power.

Goto www.airguard.com and look at the cut sheets (drawings) of the HEPA
filters they make. This style is quite common for the 600CFM and larger
HEPA filters. Hospitals and laboratories use these by the truck load.
No, they don't cost $20, its more like $220 and up.

wrote:
Robert Gammon wrote:


The HEPA filter I was discussing puts a ZERO pressure drop on your HVAC
system as the one I described has its OWN 1HP ECM2 fan inside...


A hideous waste of energy. Use a 2 watt Envirosept filter instead.

Nick


Energy or heath.

Envirosept is NOT a HEPA filter. For applications that demand HEPA,
Envirosept won't do. Envirosept is a good replacement for a fiberglass
filter. Its a good replacement for a MERV 4 filter. Envirosept is
roughly equal to most MERV 11 filters,but has a MUCH lower load on the
fan than they do.

Keep in mind that HEPA was developed to protect the workers in the
nuclear industry. As uranium and plutonium and other isotopes were
being milled into the shapes required for bombs and power plants, they
HAD to ensure that EVERY stray particle was captured in these filters.

Hospitals now recognize that they cannot get rid of bacteria unless they
use these filters. Bacteria can be as small as 0.3 microns in size. HEPA
filters will trap at least 99.97% of airborne bacteria. Envirosept says
they can capture about 45% of these particles.

As good as HEPA filters are,they have problems with carbon black.
particles size there runs down to 0.0005 microns.

For applications that need this level of fil

Richard J Kinch wrote:
Robert Gammon writes:


You need the assistance of an HVAC pro ...


You need help with your amathophobia.


Phobic. Hah

My BODY tells me when it is time to change the furnace filter. It not
fear,its chest congestion I am not aware of how long it has been since
I changed the furnace filter, until I start having fluid build in my
lungs, I have a persistent lump of mucus in my throat that will not
clear. I cough from time to time, and I may sneeze a bit. When these
symptoms become recognizable, I go look at the date on the furnace
filter and say "WOW, has it been really THAT long?? Look at that thick
layer of dust." This is usually 2-3 months with most pleated filters,
but seasonal pollens and molds can accelerate the filter change cycle.

Shouldn't you be able counteract this by increasing the area of the
filter?

To some degree, yes. That is why pleated filters get so much attention,
as they increase the surface area of the filter dramatically. Have you
noticed that the 1" UltraAllergen filters from 3M have DRAMATICALLY
increased the number of pleats?

You can increase the size of the filter say by going from 20x20 to
20x25, more filter area. Change filter media to get higher levels of
filtration (MERV goes up), or change nothing and the load on the air
handler fan drops.

You can increase the number of pleats in the filter, again more filter
area. Change filter media to get higher levels of filtration (MERV
increases), or do nothing and the load on the fan drops.

You can increase the total depth of the pleats, going from 1"to 4",again
lots more filter area. Change filter media to get higher levels of
filtration (MERV increases), or do nothing and load on the fan drops.

With each of these steps, we increase the total filter area. If the
media stays constant, say MERV7, then the total dust holding capacity of
the filter increases, we don't have to change it as often. But if the
filter media changes, and we get a higher MERV value, the life of the
filter drops, as it traps more dust faster.

To get HEPA level filtration at the flow rates needed to handle your
WHOLE house, i.e. 1200CFM or 2000CFM, the depth of the filter increases
to 12 inches or more, filter size increases to 24x24 or more, filter
media area increases to 185sq ft or more, and the type of media
changes. In most big HEPA filters, the air flows thru 12 inches of
filter media.

Frankly, that looks like a "reasonable" installation: a 2'x2'x1' filter box
with, maybe, a cheap "pre-filter" before it to pick up the big stuff. No
electrical power needed. With a 12" depth very little air would bypass the
filter. This system would greatly out perform these electronic filters and
the maintenance requirement would be "in the noise" to the point where it's
reasonable to let the HVAC guy do it as part of his yearly checkup.

In our household MERV 7 pleated media, the filter depth for airflow is
under 0.1 inch (thickness of the material in the pleat).

To push air thru 120 times thicker media, thru media that has higher
density, requires lots of fan power.

Your point is well understood and I appreciate your hard numbers. ASSuming
you can get replacement filters it seems to me that for a new installation
where you can spare the space for the filter cell (essentially double the
air path length of a electrostatic filter) you will have "as good as you can
get" air filtering. As if someone doesn't need "good as you can get" he
can have DAMN GOOD with a 3 or 6" thick filter.

Still to be consider is whether it's useful to get some odor control with
ozone followed by charcoal.


Goto www.airguard.com and look at the cut sheets (drawings) of the HEPA
filters they make. This style is quite common for the 600CFM and larger
HEPA filters. Hospitals and laboratories use these by the truck load.
No, they don't cost $20, its more like $220 and up.

Robert Gammon wrote:

My BODY tells me when it is time to change the furnace filter. It not
fear,its chest congestion I am not aware of how long it has been since
I changed the furnace filter, until I start having fluid build in my
lungs, I have a persistent lump of mucus in my throat that will not
clear. I cough from time to time, and I may sneeze a bit. When these
symptoms become recognizable, I go look at the date on the furnace
filter and say "WOW, has it been really THAT long?? Look at that thick
layer of dust." This is usually 2-3 months with most pleated filters,
but seasonal pollens and molds can accelerate the filter change cycle.

How strange. Most bodies would say "Hey, it's too cold in here!!!"
as the filter clogs and furnace airflow slows, even though clogged
filters filters better.

Nick

wrote:
Robert Gammon wrote:


My BODY tells me when it is time to change the furnace filter. It not
fear,its chest congestion I am not aware of how long it has been since
I changed the furnace filter, until I start having fluid build in my
lungs, I have a persistent lump of mucus in my throat that will not
clear. I cough from time to time, and I may sneeze a bit. When these
symptoms become recognizable, I go look at the date on the furnace
filter and say "WOW, has it been really THAT long?? Look at that thick
layer of dust." This is usually 2-3 months with most pleated filters,
but seasonal pollens and molds can accelerate the filter change cycle.


How strange. Most bodies would say "Hey, it's too cold in here!!!"
as the filter clogs and furnace airflow slows, even though clogged
filters filters better.

Nick


Bodies near Villanova may say,"Its COLD in here"

Bodies near Houston TX may say, "Its HOT in here" Look at the TMY2 data
for Houston and see what I mean.

Wife is oblivious to the condition of the filter. I change it more
often than absolutely required.

I am more sensitive to furnace filter bypass and furnace filter flow
thru of mold spores than most every one else. I get far fewer
respiratory problems living in Texas than I did in the first 20 years of
my life in North Carolina. Winters were miserable there for me. Post
nasal drip started in October, followed by a really raw throat. after a
few weeks, the flow tapered off, and got MUCH thicker. Coughing to
clear, frequent swallowing to attempt to clear, gargling with sal****er
in an attempt to clear, goto the doctor to get prescriptions for drugs.
With the coming of spring, all the problems went away.

wrote:
Robert Gammon wrote:

The HEPA filter I was discussing puts a ZERO pressure drop on your HVAC
system as the one I described has its OWN 1HP ECM2 fan inside...

A hideous waste of energy. Use a 2 watt Envirosept filter instead.

Nick

I put a K&N filter in and find I get much better performance. (joke).

z wrote:
wrote:

Robert Gammon wrote:


The HEPA filter I was discussing puts a ZERO pressure drop on your HVAC
system as the one I described has its OWN 1HP ECM2 fan inside...

A hideous waste of energy. Use a 2 watt Envirosept filter instead.

Nick


I put a K&N filter in and find I get much better performance. (joke).


Almost anything works better than Envirosept. HVAC service says HATE
these things as SO much stuff gets onto the AC evaporator coil. Several
web sites have commented on this.

Robert Gammon wrote:

Almost anything works better than Envirosept. HVAC service says HATE
these things as SO much stuff gets onto the AC evaporator coil...

Maybe they didn't plug them in. A lot of HVAC techs are stupid.

Nick