Jump to content

Is Loose-Fill Fiberglass Combustible?


Brian G
 Share

Recommended Posts

Originally posted by Bruce Thomas

Is this a double vent pipe?

I honestly can't tell. It's a big metal vent pipe (about 10 or 12 inch diameter I'd say) on an older gas fireplace. I did find a label in the attic (fallen off) that said it needed 2 inches of clearance from any combustibles.

It's a weird deal all the way around. There are two small intake vents on the wall with the fireplace, then on the backside of the same wall are two output vents. Not what one sees every day.

Brian G.

Link to comment
Share on other sites

Originally posted by crusty

The insulation in contact with the vent will cause draft problems due to the fact that it will cool the gases and prevent them from discharging properly.

Okay, you lost me on that one. How would the insulation work to cool the gases in the pipe, oh Crustoid of the Left Coast?

Brian G.

Yuh Done Went & Confusiated Me [:-boggled

Link to comment
Share on other sites

Sorry Brian, confusing verbiage, it's a relative thing within the length of the flue. This says it better. "Any insulation against the exterior flue creates an insulated section of the metal flue that does not heat in the same even rate as the metal sections not in contact with insulation. The B-vent appliance exhaust draft is inconsistent at that section with insulation against it and the draft of combustion gases swirls becoming trapped by the uneven temperatures. The products of combustion must change composition in order for the lighter gases to continue to rise. The heavier materials do not rise as readily. Water vapor is very heavy and easily comes out of suspension forming moisture that condenses on the cooler B-vent sections. Moisture condenses on the cooler vent and rolls back toward the B-vent appliance damaging the condensing fan, vent or worse the heat exchanger."

Link to comment
Share on other sites

Hmmmm...I admit this is not my best subject, but it seems more logical to me that the "insulated" parts would heat up faster than the uninsulated ones, not slower. However, I reserve the right to be entirely wrong and full of it.

Brian G.

Not That It's Ever Happened Before or Anything [;)]

Link to comment
Share on other sites

I commonly see a piece of sheet metal with a round hole or thimble isolating the vent from the drywall and any type surround to prevent the insulation from coming in contact, much like what the insulators used around unrated can lights or even wood blocking. I'll try to get a pic of one the next time I see it.

Link to comment
Share on other sites

Originally posted by Brian G.

Hmmmm...I admit this is not my best subject, but it seems more logical to me that the "insulated" parts would heat up faster than the uninsulated ones, not slower. However, I reserve the right to be entirely wrong and full of it.

Brian G.

Not That It's Ever Happened Before or Anything [;)]

I'm not smart enough to know and have a short attention span for theory. What I do know and have often witnessed is that the draft is affected by the uneven heating, be it faster or slower and condensation with the associated efflorescence has an adverse deteriorating effect on the flue and often the appliance Brian. Flames on the insulation is of little or no concern.

Link to comment
Share on other sites

Say Mike,

Do you really use "exaust bouyancy"? I'd feel the need to explain that one to a layman client. Maybe it's just me, but I tend to automatically associate bouyancy with something that floats in liquid, even though I realise it has wider meanings.

Brian G.

I'll Say a Word, and You Say the First Word That Comes into Your Mind...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...