Flex vent pipe

John Stephenson · 05-28-2007, 02:44 PM

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**DavidR** · 05-28-2007, 04:06 PM

Originally Posted by John Stephenson

What is causing the white staining at the vent connection spillage?

More than likely flue gases condensing inside the flue due to no post purge cycle.
Underfiring of the furnace is another very likely culprit.

**Jerry Peck** · 05-28-2007, 05:08 PM

If it does not have a label on in, I would not "assume" that is it listed.

Could be, but without a label - I would not say it's okay ... I'm not the AHJ and cannot give it my blessing without labeling or testing.

"Could" it have been labeled" Sure, but the label is also supposed to be permanent, meaning it is not supposed to fall off.

**Bob Harper** · 05-28-2007, 05:27 PM

Appears to be flexible liner used as a vent connector, for which it is not approved or listed. There are listed flex connectors, which are heavier, stiff and carry listing lablels. This appears to be liner adapted with single walled pipe into B-vent above and below. No draft hood connector, lack of proper support, oversized liner. Cannot use single walled connector in attics regardless if flex or rigid.

I recommend the entire run be done by a qualified HVAC tech using the same brand of B-vent installed to the listing. Then, have him inspect the unit and test it for proper setup.

**Michael Thomas** · 05-28-2007, 05:35 PM

BTW, when you do encounter listed flex B-Vent, this may be helpful:

http://www.duravent.com/docs/instruct/L206A_Sep01.pdf

Richard Rushing · 05-28-2007, 05:41 PM

Reference the white staining:

I have found that this condition really rears it's ugly head in the winter when the cold air of the attic meets the hot air gasses. The 'white' comes from the gas.

As David said, this could very well be an indication of the heater units purge cycle being much too short. At least, that was the way I was skuled.

Rich

**Eric Barker** · 05-28-2007, 06:52 PM

John,

Sorry I don't have a pic but there are flex vents that are designed for venting water heaters and furnaces. You will recognize these because they come with an adapter on the ends for connecting into rigid vents - the adapters are not field installed was in your pictures. What you saw is wrong.