I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.



--
/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/
No Good Deed -
Goes Unpunished

On Jan 23, 10:28*pm, "ps56k" wrote:
I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.

--
/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/
No Good Deed -
* * * * *Goes Unpunished

But, the pleats make the apparent cross-sectional area of the filter
approx 2x the 20 x 25 so even if the resistance per square inch of the
pleated filter is 2x the resistance of the fibreglass filter, the
overall resistance is the same. But, the pleated filters do get
clogged faster because they filter better, so you do have to change
them out more often. But, they reverse flow rinse in a laundry tub
pretty easily and can be reused after they dry out.

"ps56k" wrote:
I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.



Your right. Don't want to get dust and grime in heat exchanger though.
Sometimes increasing flow will cause dust in vents to get moving. I told my
furnace installer I wanted bigger filter size, and the goof put in a 16X20
.. I turned it into a 20X 25 myself. Same thinking. The electrostatic helps
take out that very fine grime that's hard to clean.

Greg

On Wed, 23 Jan 2013 22:28:39 -0600, "ps56k"
wrote:

I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.

The makers of HVAC units spend millions of dollars over decades
engineering filters systems for your units so you figure you can just
take them out and improve performance?

Your perception is entirely wrong. Too much air flow can impede
performance rather then enhance it. You can also clog up your coils
making for costly repairs. Your conclusion is correct, the
temperature will not be the same.

On Jan 23, 11:36*pm, "hr(bob) "
wrote:
On Jan 23, 10:28*pm, "ps56k" wrote:





I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

Running without a filter will allow dust to
clog the AC coil, resulting in even less air
flow. So, by trying to be smarter than the
designers, you're making things worse. As
Ed comments, expensively so. I've also seen
blower fans clogged badly. I've had to take
furnaces apart, and clean the blower fans.
No fun at all. I'd run with a filter all the time,
for sure.

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

"Ed Pawlowski" wrote in message
...

The makers of HVAC units spend millions of dollars over decades
engineering filters systems for your units so you figure you can just
take them out and improve performance?

Your perception is entirely wrong. Too much air flow can impede
performance rather then enhance it. You can also clog up your coils
making for costly repairs. Your conclusion is correct, the
temperature will not be the same.

Running without a filter will do a bunch of bad things,
clogging your system with dust. I think that is a very
poor idea, and should not be done.

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

"ps56k" wrote in message
...
I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.



--
/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ _/
No Good Deed -
Goes Unpunished

"Ed Pawlowski" wrote:

The makers of HVAC units spend millions of dollars over decades
engineering filters systems for your units so you figure you can
just take them out and improve performance?

They engineer HVAC units to reduce their shipping weight and size you
can carry them down the stairs into the basement.

If they really designed residential systems for efficiency, they'd have
a much larger filter surface area than they presently do, and they'd
have a duct system that allows you to bypass the AC coils during the
heating and air-circulation seasons (ie - the time of year when you just
have the fan running - no heat or AC).

Your perception is entirely wrong. Too much air flow can impede
performance rather then enhance it.

That's a function of the fan speed and blower size. Generally the more
air you can push per unit time, the more efficient you can make the
system (increased ability to transfer heat from the exchanger or to the
AC coil).

On Jan 24, 8:54*am, HVAC Guy wrote:
"Ed Pawlowski" wrote:
The makers of HVAC units spend millions of dollars over decades
engineering filters systems for your units so you figure you can
just take them out and improve performance?

They engineer HVAC units to reduce their shipping weight and size you
can carry them down the stairs into the basement.

If they really designed residential systems for efficiency, they'd have
a much larger filter surface area than they presently do,

They have those. They are called filter units, available
in a wide variety of designs. They go in the return right
before the furnace. It doesn't make sense to design a
real filter into the furnace when customer A wants an
electrostatic one and customer B wants a media type.
Plus, it would make the furnace 5" larger. With a
seperate unit, it can be located as the installer desires,
not necessarily making the furnace itself taller or wider.





and they'd
have a duct system that allows you to bypass the AC coils during the
heating and air-circulation seasons (ie - the time of year when you just
have the fan running - no heat or AC).

What exactly is that going to save in the grand scheme
of things? Instead of a simple flow through design, you'd
have sharp bends, at least to fit it into a reasonable space.
The AC coils obviously don't present such a flow restriction
that they are a problem. And the blower runs at a much
lower speed in heating mode than in AC mode, greatly
reducing the pressure drop across the coils...





Your perception is entirely wrong. *Too much air flow can impede
performance rather then enhance it.

That's a function of the fan speed and blower size. *Generally the more
air you can push per unit time, the more efficient you can make the
system (increased ability to transfer heat from the exchanger or to the
AC coil).

That I agree with.

ps56k wrote:
I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.


Hmm,
Very funny! For one, blower speed is different between cooling and
heating mode. System is designed to work with filter. Air flow should
be certain amount with filter installed and your job is to replace it
regularly depending on your situation. My filter is 16x25x5 and every 4
month I put in new one(MERV 12 ones(

On Jan 24, 1:31*pm, "Ed Pawlowski" wrote:
"HVAC Guy" wrote in message

Your perception is entirely wrong. *Too much air flow can impede
performance rather then enhance it.

That's a function of the fan speed and blower size. *Generally the more
air you can push per unit time, the more efficient you can make the
system (increased ability to transfer heat from the exchanger or to the
AC coil).

But too much is no good either. *You need balance and there are curves on
the optimum residence time needed for heat transfer to take * place. *Very
slow air movement gains a bit temperature change, but at the expense of
proper circulation.

Slow air movement results in LESS heat transfer because
the air leaving is at a higher temperature and less heat is
extracted from the combustion gases. The more airflow,
the more heat that will be extracted, the more heat you
will get out for the same energy put in. But it's a diminishing
return, moving more air doesn't come for
free, and there are other considerations.

"HVAC Guy" wrote in message

Your perception is entirely wrong. Too much air flow can impede
performance rather then enhance it.

That's a function of the fan speed and blower size. Generally the more
air you can push per unit time, the more efficient you can make the
system (increased ability to transfer heat from the exchanger or to the
AC coil).

But too much is no good either. You need balance and there are curves on
the optimum residence time needed for heat transfer to take place. Very
slow air movement gains a bit temperature change, but at the expense of
proper circulation.

In any case, dust bunnies, pet hair, pollen can build up on evaporator
coils and make the unit pretty useless.

On Jan 24, 12:31*pm, "
wrote:
On Jan 24, 1:31*pm, "Ed Pawlowski" wrote:

"HVAC Guy" wrote in message

Your perception is entirely wrong. *Too much air flow can impede
performance rather then enhance it.

That's a function of the fan speed and blower size. *Generally the more
air you can push per unit time, the more efficient you can make the
system (increased ability to transfer heat from the exchanger or to the
AC coil).

But too much is no good either. *You need balance and there are curves on
the optimum residence time needed for heat transfer to take * place. *Very
slow air movement gains a bit temperature change, but at the expense of
proper circulation.

Slow air movement results in LESS heat transfer because
the air leaving is at a higher temperature and less heat is
extracted from the combustion gases. *The more airflow,
the more heat that will be extracted, the more heat you
will get out for the same energy put in. * But it's a diminishing
return, moving more air doesn't come for
free, and there are other considerations.

yeah, like feeling drafty

"Stormin Mormon" wrote in message
...
Running without a filter will do a bunch of bad things,
clogging your system with dust. I think that is a very
poor idea, and should not be done.


hey Mormon - you may like to be on top,
but everyone else on the Internet uses BOTTOM posted messages to follow the
thread of discussion...

tnx for the comments.....
interesting tidbits...
I put the filter back into place....

On Thu, 24 Jan 2013 10:31:00 -0800 (PST), "
wrote:




But too much is no good either. *You need balance and there are curves on
the optimum residence time needed for heat transfer to take * place. *Very
slow air movement gains a bit temperature change, but at the expense of
proper circulation.

Slow air movement results in LESS heat transfer because
the air leaving is at a higher temperature and less heat is
extracted from the combustion gases. The more airflow,
the more heat that will be extracted, the more heat you
will get out for the same energy put in. But it's a diminishing
return, moving more air doesn't come for
free, and there are other considerations.


Unless we put numbers on this, it is all meaningless. How slow is
slow? How much heat potential can be absorbed, etc, etc. Absorbing
the maximum heat is also useless unless you have the air flow to
properly distribute it where needed.

The manufacturer spent tons of money engineering these things so their
settings are a damned good starting point.

"ps56k" wrote:
I've had this on again off again mental debate
concerning our furnace filter.
It's the usual 20x25, and I get the upgraded pleated version,
vs the plain fiberglass version.

However, in my mind, the pleated version
restricts the air flow more so than the fiberglass - nature of the beast.

SO - when it gets really hot in the summer,
or below zero in the winter -
I temporarily pull the air filter out for max air flow...

Now, not sure why exactly.... thinking of pushing more "treated air" into
the ducts & house.
BUT - does it make any sense ?

Since the air stream is going faster across the heat exchanger (winter),
or the A/C A-coil (summer) maybe the air outflow is higher
but the temperature is not at the max....
I'll have to take a test run with my IR kitchen therm and point at the duct
vent.


I recall putting a stainless thermometer into the forced exaust gas pipe to
measure temperature. That will tell how much heat is extracted. I also put
in a water level vacuum gauge after the filter.

Greg