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  1. #1
    Join Date
    May 2004
    Posts
    44

    Thanks for all the info so far, and another question (exterior flue)

    First, thanks for the info from previous questions about ductwork and air flow. I got assurances that if I didn't like the install, they'd make the ductwork right. I told the guys to come on out and they installed the Trane XV95 furnace (60k btu) along with a 2 ton XL16i AC, just left about a half hour ago. Everything seems fine, no excessive noise, and the unit heats and cools well.

    The 60K btu XV95 is supposed to have a line out for exhaust and a line in for cumbustion air from the outside. I have two large PVC lines going from the furnace toward an outside wall. Just before they exit through the wall however, they come together in a Y into a larger single piece of PVC, so there's only one large pipe that exits to the exterior. I'm wondering why two separate lines weren't run to the outside? The guys had gone by the time I climbed up, pulled down ceiling tile and checked this out, or I would have asked them.

  2. #2
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by steve f View Post
    First, thanks for the info from previous questions about ductwork and air flow. I got assurances that if I didn't like the install, they'd make the ductwork right. I told the guys to come on out and they installed the Trane XV95 furnace (60k btu) along with a 2 ton XL16i AC, just left about a half hour ago. Everything seems fine, no excessive noise, and the unit heats and cools well.

    The 60K btu XV95 is supposed to have a line out for exhaust and a line in for cumbustion air from the outside. I have two large PVC lines going from the furnace toward an outside wall. Just before they exit through the wall however, they come together in a Y into a larger single piece of PVC, so there's only one large pipe that exits to the exterior. I'm wondering why two separate lines weren't run to the outside? The guys had gone by the time I climbed up, pulled down ceiling tile and checked this out, or I would have asked them.
    Is it a standard "Y". What does the termination cap on the outside of the house look like?

    I wonder if this could be a coaxial vent??? Otherwise I'd think you'd have issues with flue gasses getting recycled into the furnace.

    actually I'm suprised co-axial vents aren't used. you could get that last 1-2% available out of the fuel if the incomming air is preheated with exhaust gasses.

  3. #3
    Join Date
    May 2004
    Posts
    44
    Quote Originally Posted by motoguy128 View Post
    Is it a standard "Y". What does the termination cap on the outside of the house look like?

    I wonder if this could be a coaxial vent??? Otherwise I'd think you'd have issues with flue gasses getting recycled into the furnace.

    actually I'm suprised co-axial vents aren't used. you could get that last 1-2% available out of the fuel if the incomming air is preheated with exhaust gasses.
    Actually one pipe goes out straight and the other pipe comes into it at an angle. This is all preformed stuff, speaking of the Y and the output pipe, nobody patched this together. Looking on the outside:



    The hole in the center of the outside cap is a good bit smaller than the pipe going out. I'm guessing it could be coaxial, intake in the center, and the exhaust venting from behind the housing of the cap, or vice versa, they'd be separate that way.

  4. #4
    Join Date
    Jun 2008
    Location
    Nasty Natty
    Posts
    46
    That is a concentric exhaust. We use them all the time. I think they look a lot better than a two pipe system. Flue gas comes out the front while fresh air is taken in through the back.

  5. #5
    Join Date
    May 2004
    Posts
    44
    Quote Originally Posted by Sharp Snips View Post
    That is a concentric exhaust. We use them all the time. I think they look a lot better than a two pipe system. Flue gas comes out the front while fresh air is taken in through the back.
    Thanks for confirming, pretty cool way to handle it, they only had to make one hole on the exterior. The salesman had mentioned they had a way to run the two pipes out together, but I figured it would be some kind of side by side bonded pipe, this is much neater.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,104
    Yep, nicer looking then 2 pipes.


    Did they hook your furnace up so that the stat controls staging.

    If so. Turn it up 10 higher then the room temp, and see how the noise is in second stage.
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