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Dirty HX

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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?








8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab

Comments

  • kcopp
    kcopp Member Posts: 4,448
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    Sure looks that way to me.
    SuperTech
  • Danny Scully
    Danny Scully Member Posts: 1,429
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    You clean it every year or this is the first time in 16 years @Alan (California Radiant) Forbes?
  • Alan (California Radiant) Forbes
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    Second time (tail between my legs).
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Danny Scully
    Danny Scully Member Posts: 1,429
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    When was the first time and how did it look then?
  • Fred
    Fred Member Posts: 8,542
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    Coils look to be at the end of their life, to me @Alan (California Radiant) Forbes
    SuperTech
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
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    i wonder if long loose hair could be a safety issue, when working with cordless drills etc.—NBC
    SuperTech
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    edited March 2019
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    The drill is just product placement...not used :). I'd be more concerned about no safety glasses.

    There was an error rendering this rich post.

  • Alan (California Radiant) Forbes
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    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.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    STEVEusaPA
  • invermont
    invermont Member Posts: 73
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    There something to be said about yearly maintenance
  • Alan (California Radiant) Forbes
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    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.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • hot_rod
    hot_rod Member Posts: 22,467
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    nice work that you keep track and in touch
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Paul Pollets
    Paul Pollets Member Posts: 3,658
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    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.
    Alan (California Radiant) Forbes
  • Tinman
    Tinman Member Posts: 2,808
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    Lack of maintenance aside, I think its had a great run.
    Steve Minnich
  • SuperTech
    SuperTech Member Posts: 2,205
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    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_133
    Tom_133 Member Posts: 891
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    invermont said:

    There something to be said about yearly maintenance

    Yeah 95% of Vermonters feel its a scam!!
    Tom
    Montpelier Vt
    kcopp
  • Henry
    Henry Member Posts: 998
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    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-Ed
    EBEBRATT-Ed Member Posts: 15,829
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    @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.
    SuperTech
  • heathead
    heathead Member Posts: 234
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    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.




    SuperTech
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,102
    edited March 2019
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    Worked on this one yesterday. The worst I've seen.

    Viesmann 100, 3 years old.


    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    SuperTech
  • bob eck
    bob eck Member Posts: 930
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    Alan
    Natural gas or LP gas
  • Alan (California Radiant) Forbes
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    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.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • bob eck
    bob eck Member Posts: 930
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    Would this type of dirt end up in a Firetube type heat exchanger?
  • SuperTech
    SuperTech Member Posts: 2,205
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    > @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.
  • SuperTech
    SuperTech Member Posts: 2,205
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    @Alan (California Radiant) Forbes was that boiler still functional? That's one of the worst I've seen
    delta T
  • Alan (California Radiant) Forbes
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    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.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • flat_twin
    flat_twin Member Posts: 353
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    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?