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Dirty HX

We did some maintenance on a Viessmann Vitodens WB 2 8-32 that we installed 16 years ago. Part of it was cleaning out the HX which seems particularly dirty. The condensate trap had a lot of corrosive particles (see the bucket picture) and the Gianoni coils had quite a bit of built-up corrosion, so much so that I didn't want to go at it with a credit card or even CLR.

My question is: Is this an indication of a failing HX?

Often wrong, never in doubt.


  • kcoppkcopp Posts: 3,324Member
    Sure looks that way to me.
  • Danny ScullyDanny Scully Posts: 1,098Member
    You clean it every year or this is the first time in 16 years @Alan (California Radiant) Forbes?
  • Second time (tail between my legs).
    Often wrong, never in doubt.
  • Danny ScullyDanny Scully Posts: 1,098Member
    When was the first time and how did it look then?
  • FredFred Posts: 7,733Member
    Coils look to be at the end of their life, to me @Alan (California Radiant) Forbes
  • nicholas bonham-carternicholas bonham-carter Posts: 7,778Member
    i wonder if long loose hair could be a safety issue, when working with cordless drills etc.—NBC
  • STEVEusaPASTEVEusaPA Posts: 2,715Member
    edited March 2
    The drill is just product placement...not used :). I'd be more concerned about no safety glasses.
  • The first time I cleaned it was probably 10 years ago and there was some debris, but nothing like this.

    Hehe - It's not a drill, but a DeWalt fluorescent light.

    Often wrong, never in doubt.
  • invermontinvermont Posts: 59Member
    There something to be said about yearly maintenance
  • Early January of this year, I entered my 1,000th hydronic customer which I've been collecting and serving over the last 30 years. I talk to my customers about maintenance and send postcards to ones that I haven't seen in a few years to remind them to take care of their boilers. Not all of them respond for whatever reason.

    Your boiler should be like your car. Get regular check-ups. Maybe not every year, but 2-3 years is a good idea.
    Often wrong, never in doubt.
  • hot_rodhot_rod Posts: 11,143Member
    nice work that you keep track and in touch
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Paul PolletsPaul Pollets Posts: 3,149Member
    I've already replaced more than a few of the original WB-2 models. The heat exchanger needs to be cleaned yearly or the HX is likely to have premature failure. Having the Viessmann cleaning tool is required, as a credit card simply doesn't work well between the sections. In most cases, the units were maintained and cleaned but failed anyway. In some cases, cleaning or annual service was deferred for 3-4 years.
  • Steve MinnichSteve Minnich Posts: 2,250Member
    Lack of maintenance aside, I think its had a great run.
    Steve Minnich
    "The wages of carelessness is failure."
  • SuperTechSuperTech Posts: 937Member
    That heat exchanger looks just like the Giannoni in a munchkin that we replaced last week due to leakage. Ten years old and never cleaned.
  • Tom_133Tom_133 Posts: 595Member
    invermont said:

    There something to be said about yearly maintenance

    Yeah 95% of Vermonters feel its a scam!!
    Montpelier Vt
  • HenryHenry Posts: 872Member
    Viessmann makes their own heat exchangers. They need yearly maintenance. The most overlooked part was the European P trap for the condensate. It blocks very quickly. We have saved several installations by emptying the Euro P Trap.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,289Member
    @Alan (California Radiant) Forbes

    They should take better of their equipment but most don't show their heating or Ac equipment off to their neighbors or friends.

    The shiny car sitting in the driveway is much more attractive to them.

    The way customers think, a car is a necessity, even have 2 or 3 of those. A heating system is a necessary evil thing , like paying taxes.

    Your doing what you can to take care of their equipment.
  • heatheadheathead Posts: 83Member
    What is the latest from Viessmann for cleaning. in the past they recommend Antox 75 for cleaning the heat exchangers. I would have thought that the chemical help passavated the stainless steel to make it last longer. Looking at the 2013 year instructions with the cleaning knife says chemicals can harm the heat exchanger. Call me crazy but I have water picked (for teeth) after cleaning with viessmann knife. Water picking is giving me piece of mind trying to get a deeper more through cleaning without causing more harm than good. Not sure if water picking is just pushing more things deeper in or helping flush things out. See pics of before and after. Looks like mouse droppings. The intake and exhaust are separate no coaxial pipe with the centrtherm low profile wall termination mounted 8 feet off the ground. Note third picture is behind refractory, It looks like the heat exchanger going into the cast aluminum is doing something on it's own in terms of corrosion. Pictures are from a system in mid atlantic two years into service. 2500 operating hrs.

  • edited March 19
    Worked on this one yesterday. The worst I've seen.

    Viesmann 100, 3 years old.

    Often wrong, never in doubt.
  • bob eckbob eck Posts: 834Member
    Natural gas or LP gas
  • Natural gas.

    Combustion numbers looked fine. Gas pressure was a bit low: 6" wc dropping to 5" on ignition, but Viessmann has a 4" minimum.
    Often wrong, never in doubt.
  • bob eckbob eck Posts: 834Member
    Would this type of dirt end up in a Firetube type heat exchanger?
  • SuperTechSuperTech Posts: 937Member
    > @bob eck said:
    > Would this type of dirt end up in a Firetube type heat exchanger?

    Not in my experience. I have seen the coffee grounds looking crud only building up in Giannoni heat exchangers. They seem to be pretty maintenance sensitive. Fire tube boilers still need maintenance though.
  • SuperTechSuperTech Posts: 937Member
    @Alan (California Radiant) Forbes was that boiler still functional? That's one of the worst I've seen
  • Yes, still functioning. The owner had me there because he was getting an error code for a bad sensor. Now that I think of it, it could have been a problem related to the build-up in the HX.
    Often wrong, never in doubt.
  • flat_twinflat_twin Posts: 193Member
    bob eck said:

    Would this type of dirt end up in a Firetube type heat exchanger?

    I find a small amount of "coffee grounds" in the condensate trap each year (WM firetube HX). It looks like it blows down thru the firetubes rather than piling up on the HX coils but three years worth would be nowhere near the amount shown in the photo above.
    What would cause that much crud to form? Dirty combustion air? A particular chemistry in the natural gas?

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