Subject: Re: Layman question: Duct material

From: Sarah Wanamaker <[email-masked]>
Date: 6 Oct 1995 00:39:42 GMT

[email-masked] (John Ottaviano) wrote:

>Ductboard is certainly more economical than galvanized sheetmetal, but >it is not as durable.  Branch collars have a tendancy to come loose >over time and the fiberglass itself will degenerate with moisture.  It >can also be crushed more easily than sheemetal and is obviously more >susceptible to rodents (although I doubt they'll be thrilled with the >taste of fibreglass).

	The opossums that chewed through the fiberglas ducting on my mobile home didn't seem to mind the taste at all, so be careful

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From: [email-masked] (John Ottaviano)
Date: 5 Oct 1995 08:25:23 -0400

Ductboard is certainly more economical than galvanized sheetmetal, but it
is not as durable.  Branch collars have a tendancy to come loose over time
and the fiberglass itself will degenerate with moisture.  It can also be
crushed more easily than sheemetal and is obviously more susceptible to
rodents (although I doubt they'll be thrilled with the taste of
fibreglass).  Another consideradtion for the future is that sheetmetal
ducts are easier to clean.  If you are concerned about sound, just make
sure that the first 10 to 15 feet of supply and return duct are lined with
acoustical insulation (usually standard practice). 
 
-- 
John Ottaviano

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From: [email-masked] (Noel Susskind)
Date: 6 Oct 1995 12:42:22 -0700

Richard Byrd ([email-masked]) wrote:

: Mark, stay away from fiberboard. Its main advantage is it is cheap; but
: over time it deteriorates and fiberglass blows out (its an irritant). 
: And if it ever gets wet, you throw it away, its unsalvageable.

: Never use fiberglass exposed to the air stream.

<sarcasm=on>
I know Knauf and Owens-Corning would be pleased to see this comment.  
<sarcasm= off>

The industry has been haevily spending on promoting thisa stuff.  
Personnally Im not crazy about it.  I only permit it in cheap commercial 
jobs, and in your case I would definitely say....metal, with fg wrap.  As 
for the animals, I suggest you construct barriers to their entrance.  
They are not permitted in any event in to my crawlspace, and I make sure 
nothing bigger than a baby mouse can squirm there way in.  Do sonmething 
about that.
-- 
<><><><><><><><>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><><><><><><><><><
See my web page <http://www.crl.com/~slyhorse>
<><><><><><><><><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<><><><><<<<<<><>

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From: [email-masked] (Richard Byrd)
Date: 6 Oct 1995 01:19:15 GMT

In <[email-masked]> Mark Slone <[email-masked]>
writes: 
>
>I've gotten two quotes for a heat pump system for a new 2200 ft2 ranch
>house (ducts run in a crawlspace). Both have bid some kind of
>insulated, foil-covered board for the ducts (by Certainteed). Wouldn't
>steel ducts with insulation on the outside be better? The house is in
>an area where animals may be a problem. 
>
>I guess I could see where the insulated board would be quieter than
>steel ducts, but I also wonder how they would hold up over the years.
>I'm considering a humidifier, and would that keep them too damp?
>
>Thanks for the help!
>
>-Mark Slone        [email-masked]
>
>

Mark, stay away from fiberboard. Its main advantage is it is cheap; but
over time it deteriorates and fiberglass blows out (its an irritant). 
And if it ever gets wet, you throw it away, its unsalvageable.

Never use fiberglass exposed to the air stream.

Rich Byrd
Dir. IAQ Investigations
Machado Environmental Corp.
Glendale, CA
{all opinions exclusively my own}

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From: [email-masked] (Robert Odynski)
Date: 9 Oct 1995 16:06:14 GMT

Mark, as a contractor with over 20 years experience I would suggest:
1. Get at least 5 detailed quotes c/w references of 3 recent projects.
2. Deal with contractors who are bondable, even though you are not 
asking for a bond on your project. This is a good way to screen 
your contractors.
3. I would NOT use any fiberglass duct in your system! It is likely to 
fail in your application. Rodents and insects love it.
4. I would NOT use internal duct insulation. In a humidified system, 
it is a potential breeding ground for bacteria and other nasties. If not 
properly installed it will release glass fibers into
your air system. These fibers can cause respiratory problems.
5. Use sheet metal ducts insulated with 2" thick external foil faced 
duct wrap, 100% vapour sealed, secured with flare out staples, foil tape, 
and galvanized wire.
6. Use factory insulated wire mold flexible ducts for the last 5' of 
each diffuser run. This will cut your cost and help reduce sound 
transmission.

You should check out my advice and other advice before proceeding. Get
a few qualified opinions. Your HVAC system is important to your health 
and comfort.

Good luck,
Robert Odynski

In article <[email-masked]>, Mark Slone <[email-masked]> says:
>house (ducts run in a crawlspace). Both have bid some kind of insulated, 
>foil-covered board for the ducts (by Certainteed). Wouldn't steel ducts 
>with insulation on the outside be better? The house is in an area where 
>animals may be a problem. 
>
>I guess I could see where the insulated board would be quieter than steel 
>ducts, but I also wonder how they would hold up over the years. I'm 
>considering a humidifier, and would that keep them too damp?
>
>Thanks for the help!
>