>I Remember someone mentioning once that they used an air filter in their
>home for allergies or odor control or something.  Are they very effective
>at odor control?  I have several pets and despite daily litterbox changes,
>the house sometimes smells a little musty.
 
If your house is smelling musty, and by musty you mean damp, you may want to
consider a dehumidifier.  This would not only cut down on the damp smell,
but also considerably reduce mold and mildew.  Any dampness is a perfect
breeding ground for all sorts of uninvited nasty guests.  You can check this
with an inexpensive hygrometer (you may be able to ask an A/C mech for a
"sling" type, or electronic versions are available at stores like Radio
Shack.  The considered target Relative humidity for humans is about 60-65%.
Bigger is NOT better here.
 
Well, there's been a lot of discussion about different types of air filters
available.  Besides air filtration, regular washing of bedding or specific
ferret play areas is very effective for odor.  Filter types include:
 
HEPA: a folded fine medium which is can be very effective.  The filters
themselves can be very expensive, some close to the cost of the unit.  Table
top units are least effective.  In some households that contain carpet, pets,
lots of upholstery, etc., these filters can lose their efficiency very fast
and many units suffer from air bypassing the actual filter media.  Most specs
are arbitrary and often the manufacturer is the sole source of the "lab"
results.  Little consumer tests has been performed.  Bigger is better :-)
 
OZONE GENERATORS: Certainly the most dangerous of all air conditioners,
ozone generators have been the subject of many a study and even
manufacturers are now by law required to include warnings, especially above
certain concentrations.  Some manufacturers do offer a monitor that warns
above a certain ppm.  This stuff was so dangerous it stopped the development
of the first "plasma" speakers when its developers became seriously ill.
And you thought Rap music was dangerous?!?
 
Filament "electro" static filters: Includes permanent and disposable types.
Permanent filament like the kinds sold at Home Depot are not very efficient
and are usually not able to trap particles small enough for any duration to
be very effective.  Disposables, such as 3M Filtrete, are able to collect
smaller particulate matter, but require frequent changes and cost on average
about $15.  However, they are MUCH more effective than your typical
"hogshair", spun glass, or foam A/C filters and are available to fit most
returns.
 
True electronic electrostatic filters: Includes free-standing, duct and
return grill units.  Manufacturers include Honeywell and Sears(TRION).
These units work by employing a permanent core series of plates and wires
with a "buck and boost" transformer which raises the charge often upwards of
50,000 volts, but at low ampere, and particulate matter which crosses the
plates are zapped and/or collected.  These particles are "Tazer'ed" into
submission and promise never to propagate.  These units usually have a
washable permanent pre-filter to collect large dust particles, grease, and
hair, and some include a semi-permanent(seems like an oxymoron) post filter
for gaseous(really, really small particulate like zapped spore dust) matter
and composed of volcanic rock, charcoal, and/or other vitreous materials.
This post filter usually lasts a year or so and can sometimes be "sun
cleaned" but never washed.  One drawback is the seldom but occasional "SNAP,
CRACKLE and POP" if a large enough particle like hair crosses two opposing
plates.  The core is removable and can be cleaned with household detergents.
Again, oversizing is a good rule and industrial style units are usually much
more effective than flimsy plastic consumer types.  The original cost may be
higher than HEPA(about $350), but without the high filter replacement costs,
they can be MUCH cheaper overtime.  These were approved for medical use in
the home long before HEPA.
 
ION generators: simply change the polarity of particulate matter so smaller
particles collect becoming larger particles which can then be more easily
trapped by conventional filters or fall to the floor.  Also, larger
particles are then more attracted to collect on vertical surfaces and spend
less time airborne.  Drawbacks are one, they really don't clean anything;
and two, surfaces have a tendency to yellow quickly, and when disturbed, the
particles become airborne once again, this time bigger and more potent.
 
HYBRIDS: There are hybrids, which are combinations of different mechanisms
include "static sheet" air cleaners which consist of large sheets that
collect particulate matter.  Sorta like dust flypaper.
 
Filter SPRAYS: usually oil based, though sometimes adhesive, these are meant
to enhance the performance of standard air filter media.  Not to be used
with any electrostatic types, these sprays offer some increase in
performance, but benefits are often short lived.
 
FOAM FILTERS: Typical in window A/C(s), these filters offer little by way of
performance and can actually spawn bacterial growth and muck up your
evaporator coils.
 
Finally a word about A/C units themselves: The evaporator coils are a
perfect breeding ground for mold development: a perfect petri dish for the
home.  Many sufferers of allergies are especially vulnerable to theses
spores.  It is advisable that the coils be cleaned periodically with a
strong degreaser followed by a chlorine wash to decrease numbers.  The
condensate(drip)pan should also be washed and flushed.  Tablets are
available that offer some active protection although some have been known to
corrode sheetmetal.
 
FILTERS YOU CAN'T HAVE: Biological "bag" or honeycomb filters are perhaps
the most effective, along with the use of permanent reheat systems, these
minimize all infiltration and spore development.  (REMEMBER, these usually
rely on substantial numbers to cause any harm) Unfortunately, neither are
available to most consumers and would require considerable retrofit to
install.  For now, hospitals and some clinics are usually the only place
you'll find these heavy hitters.
 
For many standard "paper" filters, you may want to occasionally spray
lightly with a disinfectant to reduce bacterial growth on the substrate
itself.  Please remember to let the spray COMPLETELY evaporate before using
the A/C and to use a non-toxic, non-phenol based cleaner(phenol-based
cleaners turn water white).
 
Finally, with all these filters, ratings can be as contrived as (S)EER's are
for A/C's.  These numbers are put forth by the MANUFACTURER, and can only be
challenged by a competitor who must bear the cost of the tests if the
ratings were in fact true.  So much for incentive.  True ASHRAE tests for
air filters are only conducted by a limited number of facilities and at
great expense and are very tough because they measure the properties over
time.
 
new Latin dictum: "qui me amat, amat et furo meam"
 
best wishes,
until next time,
alphachi
[Posted in FML issue 2077]