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Rotting heat exchangers

Riles_5 Member Posts: 13
We have a customer who i sold a boiler too, they have gone through 2 heat exchangers in probably 5 years this last one lasted only 3 years. They have tested the water in the boiler telling me it is fine, there is antifreeze in the loop. To go through 2 heat exchangers, stainless steel is unheard of. Any help would be helpful.
They tested the anti freeze, with test strips.
They say that the boiler was set up properly, and cleaned annually


  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    What is the rest of the system like? only the boiler is being affected?

    Do a full water test by titration, PH, dissolved mineral.

    Could be over pumped and causing velocity erosion.

    Has anyone ever seen electrolysis be an issue with stainless?
  • icy78
    icy78 Member Posts: 402
    They say the boiler was set up properly.
    Must be a lousy product then.😀

    No, seriously, best show pics here for these guys, and also show entire room and the combustion printout and how long it was at those combustion numbers. (Steady state combustion)
  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    Do you know what side rotted out, water or flame?
  • Riles_5
    Riles_5 Member Posts: 13
    I include pic on Monday when i get to my work emails.
    what i do know is that i asked for a water sample and the sample had antifreeze in it, i used cryo tek test strips to check it. it came back bright yellow on the strip for PH that said unsatisfactory i though, being told different from my outside sales person.
    The pic i have of the heat exchanger my first thought was improper setup, i have been cleaning and setting up boilers for some time before taking a sit down job. but with out being onsite to see it first had its just my assumption.
    Mike Cascio
  • flat_twin
    flat_twin Member Posts: 318
    I don't see a specific number for chlorides mentioned in the water test. Don't know for sure if the glycol mix would affect a water test but perhaps the fill water should be tested.
  • Riles_5
    Riles_5 Member Posts: 13
    So here is this heat exchanger. I think maybe combustion issue.
  • Riles_5
    Riles_5 Member Posts: 13
    Did a water test 7.5 pH levels everything else looked normal.
  • kcopp
    kcopp Member Posts: 3,985
    edited December 2019
    LP gas? Looks it from the Pix...May be time to switch boilers.
  • ch4man
    ch4man Member Posts: 261
    edited December 2019
    if you sold the boiler, then who is "they"
    they say its good,
    they say they tested it,
    they said it was cleaned.

    to me it looks like its been badly neglected, never properly cleaned or properly set up with a combustion analyzer

    sorry to be blunt, im a little owley tonight
  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    I would venture to guess the rest of the system is copper or has copper in it. I think it would be hard to have water chemistry that would eat the boiler and not the copper or iron for that matter.

    I would agree that it is likely the combustion side.

    Or incorrect water flow, too much or too little?
  • Riles_5
    Riles_5 Member Posts: 13
    ch4man. lol..
    That's not blunt thats the first thing i said to them when i saw it. not cleaned and not service, or not set up properly. Told it was cleaned last year. worst of all its NAT gas. or he never did a combustion test on it.
    But that's my opinion.....
  • KC_Jones
    KC_Jones Member Posts: 5,081
    Riles_5 said:

    But that's my opinion.....

    That's easily solved by having them show you the results of the combustion analysis for that boiler, I would think if they were actually doing it they would be keeping the records. Would be foolish not to for this exact reason.

    Working for an OEM manufacturer I know I would require that documentation before approving any warranty. Not that we do boilers, but I have required specific documentation prior to any warranty approvals on our products.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Jamie Hall
    Jamie Hall Member Posts: 18,903
    Ah... if that's the fire side in the picture -- seems like it -- where is the boiler located in relation to any other chemical storage? Particularly anything with Chlorine in it in any form? And what is the general air quality of the intake air? We sometimes tend to forget that combustion creates moisture, and if that reacts with anything … interesting... in the air, it can have very bad effects very quickly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Intplm.
    Intplm. Member Posts: 1,375
    Riles_5 said:

    So here is this heat exchanger. I think maybe combustion issue.

    @Riles_5 ....is this truly stainless steel? Or is it something else that looks like stainless ?
    I'm wondering if it's not "true" stainless.
    Has this happened on any others that you have come in contact with?
  • tim smith
    tim smith Member Posts: 2,460
    water tube french heat exchanger I'm pretty sure. Combustion by products. Rotted from combustion side. Not been maintained would be my guess. We have had to clean those every year with maybe 10%-15% of the amount of coffee grounds as that one has annually. When the grounds build up the acidic condensate saturates the grounds and the crystals attack the stainless steel is what we have seen and deduced. Not too scientific of a deduction but its our assessment. We have found crystals attached to stainless and when you clean them off we have found pin holes at the attachment point. Don't find many lasting more than 8-10 yrs or less.
  • plumbbob
    plumbbob Member Posts: 19
    How close is the intake and exhaust
    Were they piped close together
  • tim smith
    tim smith Member Posts: 2,460
    edited December 2019
    Even with good combustion #s after we have set these up after servicing they still build up every year. As I stated above not near as bad but 2 or 3 yrs of ignoring, especially I have found on potable hot water with these types of heat xrs. Just my opinion from experience. Btw, we don't install these just repair and maintain periodically.
    Alan Welch
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,449
    I dont think you can tell from that pic.

    Yes it's very dirty with lotsa coffee grounds, but it looks like the rusty boiler water has been intruding for quite some time near the burner.

    I agree with @Jamie Hall where is the combustion air coming from? Any swimming pools etc near by?

    By the looks of this HX it's a 750,000 or larger input boiler in a large commercial building.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Gordy
    Gordy Member Posts: 9,514
  • Riles_5
    Riles_5 Member Posts: 13
    Not sure about chlorides. I did find out there was suppose to be some boiler re-piping, from the last heat exchanger replacement,That may not have been done. I just found out. thanks for all the input.

    How do you close a discussion on here?
  • Jolly Bodger
    Jolly Bodger Member Posts: 209
    Don't close it yet. Come back when you find the culprit.
  • bob eck
    bob eck Member Posts: 929
    There are many grades of SS
    Is this job on LP gas?
    Are you pulling room air for combustion?
    If pulling outside air for combustion do you have cross contamination?
    Is this a combi boiler with internal pump?
    If the primary pump is outside the boiler do you have the correct pump that the manufacturer recommends? I would say if you have a pump that is not moving the water fast enough the heat exchanger is getting to hot pulling impurities out of the exhaust flue gas and that crap there most likely is acidic sitting their eating away at the SS heat exchanger?
    Was this boiler set up with testing equipment to the manufacturer specs?
    Oh so many questions.
    Is this boiler piped primary / secondary?
    What did the manufacturer of this boiler say about your problem?
    Please let me know what you find out.