I am in the process of learning about fibreglass lined metal ducts, and its
an old house (early 80s).
So till I figure out what needs to be done and if we can afford it, is
there some kind of air filter we can use with our heating system (not the
portable room filter kind) to get rid of fibreglass particles if any.
I was looking at electrostatic filters, does this do the job ? Is there any
specific kind/brand one would recommend ?
Until you find out if the system you have can stand the increase in
resistance, and thus, reduced air flow over the coil, none.
Use a cheaper pleated paper filter, NOT the 3M or Purolator that you see at
Lowes or Home Depot..the $1.75 ones at Wall Mart will work just as fine.
A large part of what I do is measuring air flow and air balance in my
A/C contracting business. I do not recommend ANY pleated filters
unless you KNOW that you have adequate blower capacity to handle it.
Even the cheap pleateds are restrictive. Some electrostatic filters
are fair, some are worse than pleateds. Try A+2000 brand electrostatic
filters if your contractor has them, not available to DIY. But, if
ducts are shedding, a fliter will not stop that. Best bet is get ducts
replaced or lining removed and insulation put on outside of metal
Agree with Steve - don't use an electrostatic or one of the 3M filters
unless you've had the system checked by a competent tech (and those can be
hard to find!) to ensure it can handle the decrease in airflow.
I can't tell you how many calls we get at this time of year where the
homeowner has purchased one of the 3M filters ... return isn't quite large
enough and those filters can be extremely restrictive, therefore not enough
air moving across the evap coil and you get a freezeup. Had one yesterday -
3.5 ton packaged heat pump system with a 10 x 20 (yes, 10 x 20) return and a
3M white pleated filter. This system is about 5 years old and has already
had 1 heat exchanger and 2 compressors installed ... go figure.
An electrostatic filter will not remove fiberglass from the air. If you
believe that your ducts are shedding fiberglass then you may need to place
filters across each room register and this may unbalance the system. I think
you need to speak with your heating guy.
Maybe a cheap filter has less resistance to flow when first installed but
the pleated ones work better when the dust starts to accumlute. The cheap
ones only pick up "BIG" stuff when first put in; their effectiveness
increases as the clog up.
THE reason for the pleating is to increase the surface area to compensate
for the increased air flow resistance. The more pleasts, the greated the
area and the less net resistance for a given medium.
Go figure? If a pleated filter cuases all those problems someone didn't
plan the system right. Ever think about putting in a larger capacity
blower or do you enjoy replacing the compressors.
Its already out.
The WEB makes a lemon scented spray....other contractor only supply
companies offer various brands of this same type product.
After following the OP thread that was started before, I would be leaning
toward regualr metal ducts, no insulation on the inside of them, and thus,
prob has no need for anything other than fiberglass....
ITs rare that a cheaper pleat, (thinner, not as restrictive) will create an
issue with her system, provided that its been working fine to this point.
Without you or I seeing it, there is a good chance that the install she has
is a bit older, (been floowing her original post ) and shes more than
likeley got more than enough return on the unit.
The blower...depending on the unit of course, if its older will prob had no
issues with a slight decrease.
Not to knock you, but I have used the A2000s, and found them to be right
there with the WEB style filters
I would rather use in its place in that case, an Cimatec Airscreen..
or...even a PESWO series Purolator, both of course, not sold to DIYs in most
This may be a commercial product idea. Invent a spray can product
that one can spray on a regular furnace filter to make the fibers
sticky to floating dust particles. Then we don't have to worry about
having changed the sizing or balance of the air flows. We may have
to change the filters more often but that's the whole idea. The
in-house dust get removed from the home permanently. If done often
enough we can then use regular filters again.
Dave, I'm not sure any electrostatic filter will help with fiberglass.
Just that most electrostatic filters are better filters than
fiberglass, but have a higher resistance to air flow than fiberglass.
The A+2000 has the lowst resistance of any electrostatic that I have
tested. It is also possible the dust she is getting is not actually
fiberglass. Did she have it tested?
Regular filters have something sticky sprayed on them at the factory.
Pressure drop of a pleated filter is 2.5 times the pressure drop of a
regular fiberglass filter at the same air flow. If any of you will
post your email address with spaces around the "dot", I will email you
an article on high efficiency filters that explains all this. It is in
MS Word format.
sixfoot7 @ sccoast . net
Believe it or not, Home Depot carries it.....
There is also another product by Purolator, called Facet.
Runs about $6 a can for the good stuff.
Will look for a link, or will post more in a few..
For starters, its part of the IMC, or International Mechanical Code.
Second, the OP in this case has her ducts in the crawlspace, and on a long
run, its possible due to velocity, size of duct, outdoor air temps, etc, to
lose a great deal of the heat that was originally sent down the line.
With AC ducts, without the insulation, you get sweating that will create its
own set of issues.
On Fri, 8 Apr 2005 13:02:55 -0400, " email@example.com"
That's great. Can you provide a link or more details. I haven't come
across that product before.
Why would anyone insulate the heat ducts inside a house. Any heat
loss is still within the house and therefore not actually lost until
the heat diffuses to outside the house. Ducting just helps the heat
reach the further parts of the house that would otherwise not get any,
as in heat from pot bellied stoves for example.
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