The roofers are one day into my roof job and I was deliberating having them remove the top portion of a stack that's no longer used. Finally, I said to remove it and they've put 1/2" CDX plywood over it, but it's not too late to change my mind.
It's around 5.5" external diameter and I think it's ceramic and after going through the roof it attaches down the side of the stuccoed house, and goes straight down into the ground. About 2 feet above grade level, it has a section at right angles to the wall that goes under the house into the crawl space. A foot or two from there somebody attached metal ducting, evidently to a now-disconnected gas furnace. Most of that ducting has been removed - there's a few feet they left there.
So, my guess is that they used an abandoned sewer drain and vent to vent the heater. Is this correct? I mean, a heater vent wouldn't have a portion going straight down into the ground, right?
I don't have a central heating system installed here yet, and I'm thinking maybe I should leave this stack protruding through the roof since it's already there - maybe I can use it in the future. Or should I figure I'll install central heating venting when I cross that bridge and have them continue roofing over where the top section of that stack was and eventually remove the pipe going down the outside of the house wall? And if "remove" is the answer, what do I do about the section going underground? Don't I have to plug that or something? How? Thanks for any help on this.
Dan