Racking my brain in where to find some good advice on how to disassemble an old flue pipe, it dawned on me that the experts at FHC would likely have some good tips. I would like to remove this old flue pipe (pictured) and close off/seal the opening in the attic so that HVAC return air will effectively now only come from the return register in the wall rather than also from the attic. Does this type of flue pipe disconnect/disassemble easily? Or will it need to be cut into sections to disassemble? Some more detail/context for those interested - I have an old un-used flue pipe in my house which used to connect to an old furnace (have a newer 95% efficient furnace that uses a different flue vent now). I recently discovered this old flue pipe runs through a wall cavity which also is connected to an HVAC return, and the top of this wall cavity is wide open to the attic, since the flue pipe runs up that way to the roof. Because of this, I'm suspecting my HVAC is not running as efficiently as it should since it is drawing in hot air from the attic in the summer and cold air during the winter. Additionally, the flue pipe becomes very hot during the summer since ~8-10 ft of it sits in the hot attic and subsequently much of the length in the wall cavity heats up as well (you can feel the warmth on the wall sections around this cavity where the flue pipe runs). A couple related notes - 1. There is a separate flue pipe for my water heater, if anyone is concerned that this old flue pipe might still be connected to something. The bottom end of it terminates in the crawlspace and is connected to nothing else. 2. I am aware closing/sealing off the opening to the attic still will not guarantee that all return air is coming from the register in the wall which is connected to this same wall cavity. HVAC guy recommended I get a sealed box put in, increase the size of the register itself, and run a slightly larger hose back to the HVAC unit itself. But I have a strong suspicion this will definitely help.
Not sure I follow completely...if you have the chimney pipe blocked off, how are you getting return air being sucked through it? Also, why are you taking return air from the attic? Return air should be coming from the heated/cooled space. If you need to seal up the HVAC ducts better, you can do a lot with a roll of foil tape...
If you remove that white tape or whatever it is you’ll see one side of the connection. That should give you a good clue as to how it’s assembled. so if I understand correctly at one time your furnace chimney and HVAC once shared an open chase? Dang, can’t get much more illegal than that Glad to hear that’s been rectified. Probably why they left it open to the attic. Otherwise the return air might suck the gases out of the chimney if there was a leak. Not my field of expertise. Ok I don’t have a field of expertise,,,,couple small grassy patches maybe. Have no advice beyond look at the one connection that you have.
Just my 2 cents but likely just slip fit connection possibly wit a couple of self tapping screws on each joint?
I think my initial post here was a little confusing and probably had too much detail - I had an old furnace flue pipe which was no longer used in my house which ran through a wall chase and up through the attic to the roof. I found that where this chase wall connected to the attic, the wall cavity was open to the attic. In the same wall chase, my HVAC return is connected to the living space. I found that during hot days this wall became very warm I believe due to that flue pipe heating up from ambient air in the attic, as well as the fact that hot attic air was being drawn down into this chase wall cavity. I attached a illustration to help explain what the layout looks like (please note this is not to scale by any means). Since I posted this originally, I removed the old flue pipe and installed a plywood panel at the top of the wall chase to separate this space from the attic, and added fireblocking sealing foam around the perimeter of the panel to seal it further, plus put insulation on top of it. Additionally, I sealed off where the flue had originally entered the wall chase from the crawl space area with a plywood panel. Since doing this, this wall which used to feel very warm on hot days has stayed a normal temperature, and I feel like I notice my AC running less often.
