[ct2]

If I understand things correctly , it was common practice to insulate duct work on the external surfaces untill the issue of mold came about.

Now new ductwork is being insulated internally absorbing the moisture that caused the mold problem.

My question about this is , Isnt it just as bad to breath the airborne particals of fiberglass from the internally lined ducts?

 

[ct2]

Is this such a stupid question that no one wants to answer it?

or am i wrong with my understanding about lining ducts?

 

[teddy bear]

If I understand things correctly , it was common practice to insulate duct work on the external surfaces untill the issue of mold came about.

Now new ductwork is being insulated internally absorbing the moisture that caused the mold problem.

My question about this is , Isnt it just as bad to breath the airborne particals of fiberglass from the internally lined ducts?

Insulate outside of vapor barrier for heating ducts in a cold attic. Insulate inside the vapor barrier for cooling ducts in high dew point attics. All modern duct board is coated to avoid movement by air. "absorbing the moisture" How and why does that happen? Only if located in a very cold attic during the heating season. Not possible in a hot attic during the summer.

 

[bldgcode1]

Duct insulaton has little to do with trying to "absorb" moisture. You don't want the insulatin to get wet as it loses its insulating value when it absorbs water. If the system is installed properly interior or exterior insulation with the proper vapor barrier will stop condensation problems, which allow moisture build up, which encourages mold growth.

I think maybe your understanding of where the insulation is placed is a little vague.

 

[cxagent]

If I understand things correctly , it was common practice to insulate duct work on the external surfaces untill the issue of mold came about.

Now new ductwork is being insulated internally absorbing the moisture that caused the mold problem.

My question about this is , Isnt it just as bad to breath the airborne particals of fiberglass from the internally lined ducts?

This sounds like such a rationalization that it appears to be a troll.

Others may have different ideas, but here is my opinion -

Years ago ducts were lined for several reasons -

1) The primary reason was duct liner could be installed in the shop instead of on the job site. This made duct liner cheaper to install than duct wrap insulation.

2) Duct liner could be installed on exterior ducts (exposed to weather) since the sheetmetal formed a weather shield. This made it cheaper to install duct liner for outdoor installations.

3) Last and least is duct liner provided some attenuation of sound traveling inside the duct. This was the reason most frequently given for the use of duct liner.

Now to address your points. If the duct liner was "absorbing the moisture that caused the mold problem", where did the absorbed moisture go? Wouldn't the liner get saturated with water at some point? Wouldn't water standing in duct liner encourage mold gowth instead of reducing it?

Many studies have shown the only way to deal with moldy duct liner is to remove it. Generally, that means removing and replacing the entire duct. Lined ducts are a HUGE problem once mold is in the ducts.

Other studies (generally by the fiberglass insulation industry) say that any airborne fiberglass is gone within hours to days of the first time the ducts are used. I point out the source of those studies because it is hard to believe they are completely objective. However, more and more data is supporting that the airborne fiberglass doesn't last long. Other studies also show that airborne fiberglass causes less health problems to building occupants than mold.

[Edited by cxagent on 01-16-2005 at 05:11 PM]