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Packaged rooftop heat exchangers failing

RayWohlfarth
RayWohlfarth Member Posts: 1,656
in THE MAIN WALL
We service quite a few packaged rooftop units because almost every commercial building here has them. I am starting to notice more cracked heat exchangers than ever before. We just had two 10 1/2 year old rooftop units with cracked heat exchangers. Are you seeing the same thing? Could it be the gas? We are seeing lots or fracking here. Just curious Thanks.
Ray
Ray Wohlfarth
Boiler Lessons

Comments

  • Dan Foley
    Dan Foley Member Posts: 1,265
    Ray,

    We are seeing the same thing. Paper thin heat exchangers do not last long.

    Here are two heat exchangers we replaced a couple of weeks ago. 9-year old Trane gas packs. Pinholes and splits on the welds. The welds seem to be the weak point.
  • Dan Foley
    Dan Foley Member Posts: 1,265
    Pictures did not post
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,656
    Thanks Dan Its getting worse and we check gas pressure and static pressure.
    Ray Wohlfarth
    Boiler Lessons
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    13 yr old Lp unit last week with holes on the bends. My cleaning brush went right thru on multiple tubes.
  • John Mills_5
    John Mills_5 Member Posts: 952
    Common. Can't have the HX in the cold air stream but packaged units do, with a couple of exceptions. Our supplier only gets them with stainless steel HX to avoid this.
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,656
    Bob did the client blame you? Thats kinda scary
    John I agree but we used get 20-30 years out of older units and lucky to get 10 now
    Ray Wohlfarth
    Boiler Lessons
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    Not this one. Very tolerant. A 90 plus could have easily been installed inside @ split system back then, and he knows it. He was thinking space issues then.
  • Marz
    Marz Member Posts: 90
    I wonder what gauge that heat exchanger is. Reminds me of a run of *York* oil furnaces that (*If I remember right*) were 14-16 gauge and most of them lasted 10-15 years. I believe these heat exchangers should be a minimum of 12 gauge no matter what fuel they are burning. I guess a 25 year life expectancy is a lot to ask for these days...
  • SWEI
    SWEI Member Posts: 7,356
    edited December 2016
    Lack of adequate post-purge (thanks to the AFUE scoring scheme) quite likely contributed to these. @captainco teaches a fix for that.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,495
    Also, packaged units are usually bought based on cooling capacity (a 10 ton unit, a 15 ton unit) and the heating input/output is what it is.

    Most of the time the heating is way oversized, a lot of starts and stops, short cycling rotted out flue boxes and worse too much expansion and contraction on thin cheaply made heat exchangers
    Bob Bona_4
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    I don't work on any of this equipment any more, but I do know that a lot of the problems with water quality in hydronic systems is directly connected to the use of chlorides for road de-icing. I know for a fact that vehicle traffic stirs this stuff up into the air. Just wondering out loud if maybe the HXer failures you are seeing is related to the excess use of chlorides on our roads. It's eating our bridges for sure...

    ME

    There was an error rendering this rich post.

  • RayWohlfarth
    RayWohlfarth Member Posts: 1,656
    Lots of good points Thanks Just thinking it may be thinner metal but can't know for sure. I just tell customers they day of 30 years furnaces are gone.
    Ray Wohlfarth
    Boiler Lessons
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    edited January 2017
    They don't make them like they used to, for sure... See you in Las Vegas Ray! :smiley:

    ME

    There was an error rendering this rich post.

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