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  1. #1
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    leaking concentric vent

    Just finished a call at an apartment building that I am running all the 1 year warranty for (installing company is 2.5 hours away) and found something interesting. A week ago I got called out for a no heat to a unit I was in about 2 months ago. The gas valve bad for the second time in two months. But this time there was rust all over the cabinet, burners, and gas valve. the intake air comes into the top of the unit (york 95.5 upflow). The only way water can be getting onto the burners and gas valve is if it is coming from the air intake. This apartment is on the top floor (of 3) and vents out the roof with a concentric vent. So somehow water is getting in the intake line and leaking back onto the furnace and killing the gas valve. Today, I was on a no cool call for a different 3rd floor apartment, and in talking with the resident, he said his heat did act up a little a few weeks ago but ever since is fine. After getting the ac running I told him since i was there i was going to start the furnace and see if anything stands out. turn ut on, walk to the unit, pull the blower door off, the compartment is filled with rust!!

    Now im concerned that some, most, or all of these concentric vents are leaking onto my gas valves. I have not been to the roof yet, my 32' ladder can not reach so I need to get a 40" or a lift to get up there. I also can not find a cut away drawing of a concentric vent kit to see where this water may be getting in.

    So my question to you masterminds is, how could this water be getting in the intake of the vent kit, if the its pulling the air in from the bottom of the cone?

    Since I plan on inspecting all 18 units on the roof now, I want to be prepared so my lift rental cost is put to good use.

    Thanks for the help.
    Ben

  2. #2
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    Nov 2008
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    is it plumbed properly? intake goes in the side and exhaust goes in the end. So basically the exhaust is straight piped and the intake is from a pipe that is around the exhaust. Make sense? you do not need on the roof to figure this out just in the attic.

  3. #3
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    Quote Originally Posted by DOGBOY View Post
    is it plumbed properly? intake goes in the side and exhaust goes in the end. So basically the exhaust is straight piped and the intake is from a pipe that is around the exhaust. Make sense? you do not need on the roof to figure this out just in the attic.
    Fair question, answer is I dont have a clue. I know how the vents are build but I thought looking at a cutaway might help. But I understand what your saying. I guess I just built in my head that no one would do that. I guess I should not give them to much credit seeing as how I have made great money in the 9 months the building has been open fixing their mistakes. Ill check that first before dropping the rental fee, its just a bear trying to coordinate with their maintenance staff to get in to stuff like that.

    Thanks for making me think past my own thoughts that no one would pipe it wrong.

  4. #4
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    Nov 2008
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    did you google concentric vents?

    http://www.diversitech.com/Product-L...0000005QG0EIAW

    look at these pictures.

  5. #5
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    Mar 2016
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    Quote Originally Posted by DOGBOY View Post
    did you google concentric vents?

    http://www.diversitech.com/Product-L...0000005QG0EIAW

    look at these pictures.
    Been there seen that plus more. I was looking for something like where they would cut the vent right down the middle and show how everything fits and seals together inside the unit. I was thinking somehow, the exhaust pipe was allowing water to run down the outside of the pipe, which would then become part of the intake, and then run all the way back to the unit. But like you said before, it may be more reasonable that they piped it backwards. Seeing as how my no cool call today was from the disconnect not being pushed in, it possible with this crew. (the cover was zip tied shut like all of them have been, so i know its still from the original install.)

  6. #6
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    It is piped wrong. Some body may have a cutaway of it but it is a pipe in a pipe. I do not think that the exhaust can leak in to the intake. and for several of them to be doing it now way. Sounds like an installer was confused. Or new. Or did not care. Or?

  7. #7
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    The ones I have installed differ slightly from what is pictured in your link. the cone and exhaust pipe are 2 different pieces. therefor, since it is not a single piece construction, and the exhaust sticks past the intake cone a few inches, hypothetically, the rain water hitting the outside of the exposed exhaust, "could" work its way down into the intake. I think! thats why i would like a cutaway. possible, yes... probable, no.

    thank you though you really did get me on a different train of thought. From what i have been repairing, these guys are not first class installers. I just figured since I have never piped one wrong no one could. I mean im not the brightest shining bulb.

  8. #8
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    Jan 2010
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    Can you repipe the intake at the furnace so the intake comes down beside the furnace into a tee? Take the branch over to the the intake on the furnace. Put a drain on the run end. Kind of like a drip leg.

    Sent from my SM-N910W8 using Tapatalk

  9. #9
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    Quote Originally Posted by BALloyd View Post
    Can you repipe the intake at the furnace so the intake comes down beside the furnace into a tee? Take the branch over to the the intake on the furnace. Put a drain on the run end. Kind of like a drip leg.

    Sent from my SM-N910W8 using Tapatalk
    I can picture what your saying. But to be honest going from memory I am not sure if there is room for that or not. on one side is the wall of the closet, the other side the vent runs out and if I recall correctly, the vent stubs right out then a 90 up. putting is close to the cabinet and not a lot of room for the intake knock out on the side.

    Ill have to take another look at that. That thought crossed my mind at one point as well.

    Thanks,
    Ben

  10. #10
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    Mar 2015
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    As far as 'concentric' style,approved,vent term's involving 'cones'.I've never encountered such.
    2 pipe separate yes. But Cones with an extended Ex pipe above the cone,No.
    BTW,How do you know this beings you have not been on the roof?
    Line of site from the ground?
    Somebody's 'adaptation of the OEM?
    Seen this a time or two where the Concentric was actually Extended some 10' to the Cone.Nobody could explain this 1. Figure it had to do with a split level and the Vent had to terminate above the 2nd story so to speak.Fubar.
    never piped one wrong
    Yeah, I've seen a few done Backwards.
    The only way your getting 'water' back thru the Intake is either by rain or snow infiltrating back in or the Ex is not completely solid out the exit and condensing into the intake.Which would likely cause a flame out code as your in taking 'burnt' air lacking Oxygen if 'that bad but a possibility.
    No matter how long you have been doing this,
    Go back and reread the Basic's.You WILL Learn something.
    Why is it called,an Act of GOD when IT has Nothing to do with Him?
    Will of the Devil would be more appropriate IMO.Just Saying.
    PSALMS, 18 & 25.

  11. #11
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    Mar 2016
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    Quote Originally Posted by mrkelly View Post
    As far as 'concentric' style,approved,vent term's involving 'cones'.I've never encountered such.
    2 pipe separate yes. But Cones with an extended Ex pipe above the cone,No.
    BTW,How do you know this beings you have not been on the roof?
    Line of site from the ground?
    Somebody's 'adaptation of the OEM?
    Seen this a time or two where the Concentric was actually Extended some 10' to the Cone.Nobody could explain this 1. Figure it had to do with a split level and the Vent had to terminate above the 2nd story so to speak.Fubar.

    Yeah, I've seen a few done Backwards.
    The only way your getting 'water' back thru the Intake is either by rain or snow infiltrating back in or the Ex is not completely solid out the exit and condensing into the intake.Which would likely cause a flame out code as your in taking 'burnt' air lacking Oxygen if 'that bad but a possibility.
    So maybe I am not explaining what I have. if you look at the attached picture, http://www.diversitech.com/Product-L...0000005QG0EIAW , the bottom of what I am calling the cone is the intake. from reading your post you have seen these i guess im just trying to clarify. But in the ones I have installed the whole piece that looks like a cone is its own separate piece. So i stub what would be the intake out the wall/ceiling, stick the cone piece on, then insert the piece for the exhaust. IF.... these are of the same construction as the ones I get, the i THINK it is possible rain could run down it. THINK is capitalized cause its trouble when I have to think

    I remember the first time I saw one of these vent kits come undone and really screw the flame up. pulling the exhaust fumes right back in the intake. made me scratch my head for about 30 seconds before i told myself to go check the exterior penetration.

  12. #12
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    And to the issue of not being on the roof yet....
    technically, this is still under warranty from another company that is paying me to do all their warranty work since they are 2.5 hours away. So really for something that involves this added cost needs to get an okay from them. So after today and seeing the second unit leaking, I called to see what they want to do. They just want it to be July 1 so they can be done with this place all they care about at this point thought.

  13. #13
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    Sep 2015
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    Are we sure that the leak is from water entering the intake. If the furnace is heating the condensate in the exhaust pipe will leak out of any loose and bad joints on the exterior of the pipe.

    If the water is coming in through the intake and into the cabinet, it is likely that the the insert pipe is installed wrong or not glued. I've used these concentric vent kits a lot. If water is coming down the intake and the cap is on, the condensate from the exhaust can be entering the intake. This can only happen at the concentric vent kit before the pipes become separate.

    2 bad gas valves? Have we taken a gas pressure reading?
    Last edited by DuctLife7926; 04-01-2016 at 09:23 PM.

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