Flue Attachment Mystery

[Stephen G Sheldon]

Saw the attached looking arrangement on a basement forced air furnace being vented to the side of the house. What are these components in the picture?

[Raymond Wand]

Its a power vent. Most likely used on high efficiency oil fired furnace or where their is no vertical chimney or where the horizontal flue is too long or slope cannot be adequately provided. Don't see many of them up here but have seen them.

There is a pressure switch (round disc) which will shut down the furnace if positive pressure on the vent is inadequate.

[Stephen G Sheldon]

Raymond, Thanks for your help

[DavidR]

Was that attached to a furnace that had an open drafthood Stephen?

If so you might want to call it out as having the potential to be unsafe.