Some clarifications, using industry standard nomenclature, So that we
are speaking the same language:
"Here's a basic comparison. "Electrostatic" below means Honeywell
types with fine wires with a high voltage and no charged media:"
The filters that use electricity to charge plates or media are normally
called ELECTRONIC AIR FILTERS in the trade. While they don't use much
electricity, the power output is usually several thousand to as high as
ten thousand volts. It is the high voltage (low current) that produces
ozone, due to corona discharge effects. The higher the voltage, the
more ozone is produced. Many such filters have ozone reduction options
that reduce the output voltage to reduce ozone generation. This also
reduces their effectiveness and cleaning power. The ELECTRONIC air
cleaners have very low resistance to air flow. If you want a high
efficiency air filter, this is the way to go.
ELECTROSTATIC FILTERS are those that use the high velocity of air to
put a static charge on plastic media, much like rubbing your shoes on a
rug as you walk across a floor. They usually use a couple of different
plastics to enhance the effect. ELECTROSTATIC air filters have no
The envirosept does not fit neatly into either category, as far as I
Nick, a 20 x 20 fiberglass filter at 800 CFM has a pressure drop of
.08"WG. The net opening of that filter is 18" x 18", or 2.25 Sq. Ft..
800 CFM/2.25 Sq. Ft. = 355 linear feet per minute (FPM). Compare this
to the Envirosept pressure drop of .22" at 375 FPM. At very close
velocities, the Envirosept filter has a pressure drop of just under 3
times that of the fiberglass filter.
The fan laws apply to fans, duct systems and coils. I have also found
it to be very close with air filters that I have tested. Nick, I test
air flow with a flow hood, a hot wire annemometer and a digital
differential pressure gauge. I have been using a flow hood for 17
years. I have been using the other instruments almost as long. I am
not pulling these numbers out of any body oriface as you suggest.
(Have you been hanging around alt.hvac.group too much?? That kind of
language does not belong in an intelligent conversation.)
As to AC systems cooling too much and dehumidifying too little, I agree
there. Paying attention to load calculations and proper air flow would
help tremendously. Most AC systems dehumidify best at air flows of 350
to 400 Cubic Feet per Minute (CFM) per ton. If systems deliver proper
air flow, there would be much less need to oversize them as most
contractors do. If the duct systems matched the equipment better,
instead of being undersized, there would be more blower capacity for
high efficiency filters.
Because so many people now purchase pleated media filters at the home
centers, I recommend Variable Speed (VS) blowers when I sell
replacement systems. Variable Speed blowers are more efficient than
standard blowers. Typically, the SEER goes up at least 1 (12 SEER
increases to 13 SEER) when changing from a standard to a VS blower.
Also, while most standard blowers will produce rated air flow with a
coil installed at .3 to.5 inches water column external static pressure,
a VS blower will produce rated air flow at .8 to 1.0 inches water
column external static pressure. In addition, the VS blower will speed
up as the filter loads up, producing nearly the same air flow at
different filter pressure drops. I have measured this in the field, it
is not just some marketing balony from manufacturers.
I don't dispute that the Envirosept does a MUCH BETTER job of cleaning
the air. My problem with it, and other similiar products is that
significantly reduced air flow adversly affects performance of heating
and cooling systems already installed and designed to work with
standard air filters. That is if any design work was done on them at
Just remember that whole house AC systems are a SYSTEM. Anything you
do to one part of the system affects the rest of the system.
By the way, I would not recomment using a "mister" or swamp cooler here
in South Carolina. Your customer would probably come to blows with you
over that. It might work wellin your climate up in Mass though.
Remember that this group goes to people all over, what works in your
climate may not work in other climates.
By the way #2: What the heck is coolth??