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Leaking HX on Vitodens 200

Paul PolletsPaul Pollets Member Posts: 3,017
This HX from a Vitodens 200 was installed 7 or 8 years ago (by others) and poorly maintained. When we were called in to service it, it was loaded with debris and faulting the computer. The vent collar connection for the co-pipe was melted through the inner liner at the top of the boiler. After cleaning the appliance, we found the HX had a leak within the helical SS coil. The replacement HX took 7 days to get to Seattle, but that's another story. Never seen a leaking HX on a Vitodens before.


  • IronmanIronman Member Posts: 3,430

    Lost flow and over-heated. Wonder if it was ever set up correctly.

    It just goes to show that even the best products aren't "fool-proof".

    So many of us Americans haven't grasped the importance of proper maintenance on HVAC equipment.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • SpeyFitterSpeyFitter Member Posts: 420

    That's some serious lack of maintenance.

    The Coaxial venting system tends to cool the exhaust as it travels outwards and the intake travels inwards also imparting some heat to the incoming intake air which raises combustion efficiency, as many of us all know. Obviously the area where the inner, exhaust pipe connects to the heat exchanger will have the highest temperatures but consider that when the boiler is running there is still a good flow of intake air in that area pictured. For that exhaust pipe to fail like that, even rated at around 230-250 degrees like most polypropylenes are rated for, suggests some SERIOUSLY high exhaust temps. I'm gonna buck a wild guess - AT LEAST 280-300 degrees.

    The nice thing about coaxial venting is it is also very safe, especially the way Viessmann does it. In this case, the exhaust leak would be reingested into the intake and not dumped into the space. But this is not something you want occurring on a prolonged basis. As some have pointed out in the past reinvesting exhaust into the intake air will reduce the PH of the condensate even further to the extent that it could due some damage to the stainless and in some cases could cause the boiler to have ignition failures.
    Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
  • Paul PolletsPaul Pollets Member Posts: 3,017
    Mod Con Maintenance

    We urge our customers to clean their mod-cons yearly, and most of them do. Those that don't are warned of the possible consequences of loosing heat or hot water when it's cold and very inconvenient. This repair was somewhat inevitable. The owner didn't have a clue about the details of his system,or proper maintenance procedures, and the installer recently went out of business.
  • Tim McElwainTim McElwain Member Posts: 3,897
    Paul does this 200

    have the Lambda Pro system just curious as to how that system would react with recirculation of products of combustion.
  • Paul PolletsPaul Pollets Member Posts: 3,017

    This is a W2BA model, without the Lambda gas valve.At least the sensor shut down the boiler when the debris the point of no return!
  • RE:Leaking HX on Vitodens 200

    In this case due to over heating the inner pipes got melt and causes such type of problems.We must take care of this because these equipments are very costlier can be maintained under supervision of experience persons and leaking of pipes must be repaired as soon as possible for preventing further loss.
  • Larry (from OSHA)Larry (from OSHA) Member Posts: 677
    more than a little neglected

    Too bad about the V.  I'm actually surprised that there was no inlet-outlet differential limit fault like on the Knight boilers.  Or, for that matter, a low flow fault.  I suppose there needs to be a flow switch for that one.  I don't recall anyone posting any pics of any Vitodens that look that ugly.  Maybe most V owners have periodic service.  But that does prompt me to do my annual service on my Knight.

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