Ductboard vs. metal ducts?
Comfort Mart Distributors
Fiberglas duct board offers a nice place for mold and other organisms to
live. Not very healthy, especially if you want to install a humidifier at a
later date.
--
J.P.
The Edge wrote in message <65312j$4ge$1...@gte2.gte.net>...
>Duct board in most cases is the cheapest way to go and in your case I
>certainly would not think that it would cost that much more to make a sheet
>metal plenum assuming those contractors have a sheet metal shop. It is
very
>possible that they do not. The thing that has always concerned me is fiber
>glass material that it is made of. I am sure some of the material enters
>the air stream but apparently is not enough to cause harm. Also I would
>strongly encourage you to have a load calculation done on your house before
>spending the money on the system.
>
>
>
>
Jeff/Laura Domogala
One comment that I've heard in this forum before regarding ductboard:
"I've yet to see a mouse eat through sheet metal"
I think this speaks for itself. If the duct was going to be in a spot that
animals might get into, I'd go sheet metal. Otherwise, ductboard is cheaper and
is already insulated. IMHO, I think a ductboard duct is quieter than a sheet
metal duct.
When getting your bids, the ductboard job better be less expensive than a sheet
metal job. The ductboard is by far cheaper, and it is much easier to work with
when installing (such as cutting out takeoffs). No snips required, just a good
knife that'll cleanly cut through the fiberglass.
Another concern would be the effects of having a humidifier in the ductwork, if
you were to install one. The fiberglass is an easier place for mold and mildew
to form on ductboard.
That's my $.02
Jeff
----------------------------
Jeff/Laura Domogala
Windham, NH
domo...@scoot.netis.com
http://www.netis.com/members/domogala
Augustine
Uraprat wrote:
> Hi All,
>
> I am in the process of planning and purchasing a heating and A/C
> system
> and have been stumped on a final decision, which I must make. My
> favorite HVAC
> contractor (of 3), says that they prefer to sell, use, and install
> ducts made
> from ductboard instead of fabricated metal. I believe it is much
> cheaper and
> easier to fabricate and install ductboard, which would explain their
> preference. They said that they will do metal ducts in locations,
> where it
> makes sense or where it is required, but for an average home ductboard
> is fine.
> I have always heard that ductboard is a really poor choice, compared
> to metal
> duct. Does ductboard suck as much as I think it does?
> If it helps, the system is going to be installed in the basement
> of a
> house which is a one story with a full basement, which I am finishing
> off and
> is going to be heated and cooled, the ductwork will not be boxed in,
> it will be
> exposed in the finished rooms. Total square footage of the house (up
> and down
> stairs) is about 3250 square feet. Outside temperatures in summers
> range in
> the mid 80's to 90's and winter extreme lows might be -05 to -10
> degrees F.
> Any help, suggestions, or opinions will be greatly appreciated!
> Thanks
> for your time.
>
> Best Wishes,
> Ura...@aol.com
I replaced my own sheet metal plenum and trunk with duct board some 5
years ago and have been quite happy with it. I was able to save a lot of
money as I was able to do the job all by myself and did not need to buy
and bend the sheet metal or have a shop do it. Ductboard is also much
more forgiving of mistakes in measurement than sheet metal. One concern
I might have about your situation though is having it exposed in the
basement. Ductboard is strong enough to hold up for many years if it is
left alone but if it is in an area where it might hit, kicked or sat on,
you might have a problem.
HyJude22
Ductboard and duct liner both sux. The fellow that replaced his duct his self 5
years ago better hope he can replace lungs his self. It cant be good to have
air blow over fiberglass into your living space. Ive been a union sheetmetal
worker 25 years and there is nothing better than metal.Thanks only my opinon.
ChipJacobs
I see about $20,000,000 worth of HVAC systems a year... I have yet to see a
duct board system that is over 10 to 15 years old that is still in one piece,
holding air.
Sonofdawra
>Another concern would be the effects of having a humidifier in the ductwork,
>if
>you were to install one. The fiberglass is an easier place for mold and
>mildew
>to form on ductboard.
>
>
What does the humidifier have to do with it???? Somebody please explain. The
air has a higher moisture content in the summer time than in the winter time.
In supply duct in the summer with A/C running, the air is near dew point. I
would think that in the winter time with the furnace on and the humidifier
running that the heated supply air would still have a relatively low RH by
comparison.
On the RA side, the air's RH is definitely higher in the summer than the
winter. Most central A/C units that are sized using Manual J [or similar] are
sized to maintain an indoor RH of between 50 and 55% during the summer A/C
cooling season.
Would someone out there explain what I'm missing?
Mark Elder
Here is one possible senario where a humidifier could cause a problem.
Suppose the duct is run in an unconditioned space (attic or crawlspace)
and the humidifier increases the moisture level of the supply air close
to saturation. During winter conditions, the duct is going to loose
heat to the surroundings and lower the temperature of the supply
air. If it drops enough, the moisture will condense inside the duct.
Some of my larger clients who have their own engineering staffs actually
request RH sensors in the duct down stream of humidifiers to make sure
they do not get into this problem.
Regards,
Mark Elder