running flexduct through unused bvent
hmj
| Posted in Energy, Heating & Insulation on
I need to run a line of flexduct from a basement up to a second floor attic. There is an old b-vent, leftover from when the furnace was converted from oil to direct vent natural gas.
Anyone see any problems with running it through the old vent instead of pulling it out? Multiple attachment points inside the chase would make it a royal pain to remove the vent.
Tahnks in advance.
Edited 9/23/2009 12:33 pm ET by hmj
Replies
Any chance of some goofball trying to re-use the vent in the future while your stuff is inside? As long as your duct enters at the very bottom of the vent I would think this unlikely.
Scott.
Nah, no chance of not seeing the flex. I would come in the through bottom and cut a hole to access it from the attic.
Is the B-vent pipe clean enough inside, or can you clean it up, so as to use the pipe itself as duct, just connecting at the ends? Flex duct introduces a lot of pressure drop, restricting flow.
I uncapped it and got a facefull of soot... I could probably scrub it with a chimney cleaning brush, but I'd be worried about a lingering smell of soot/smoke. Probably 20 years of oil soot on the pipe.Flexduct is pretty restrictive, but would probably be a step up from the leaky sheet metal ducts already there.
If the B-vent appears to be in good shape and clean enough, I second DickRussell's suggestion.
If you really want to use the B-vent as a chase for flex duct, no problem I can see from what you've described.