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Black particles in water: Navien tankless water heater to blame?

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cry1130
cry1130 Member Posts: 1
in Water Quality
Small black particles started appearing in our water a few weeks ago. Appears to only be the hot water. We have a Navien tankless water heater. I'm not sure the model but have attached a picture of the inside. Looks relatively new (we bought the house a year and a half ago). We had the Navien flushed/serviced. Did not fix the issue. We had the valve on the main water line into the house replaced as recommended by a plumber (in case rubber is the issue). House has copper and PVC pipes. No visual evidence of flexible/rubber lined piping in the home. We're not sure exactly what the particles are. I have attached a picture. They smear when you rub with your finger. Any ideas as to what this is and how to fix it?

Comments

  • Intplm.
    Intplm. Member Posts: 2,714
    Those particle are very hard to see. Are you sure the particles are only coming from the hot water ?

    It could be that the hot water is extracting those black particles out of the water when the water is heated. The thing that I can't tell is how they smear when rubbed.

    A few questions.
    Have you had your water tested?
    Is there a water filter and water conditioner on your water main?
    Is this city water or a well?
    From what water faucet did you take the sample from?
    It could be normal build up coming through your faucets that is built up in the faucet aerators ?

    Maybe remove and clean the aerators on your faucets ?

    Try draping a white cloth like a handkerchief over a glass and turn the faucet on drawing water through the cloth? Then look at the cloth.
    Hope these things help. Please respond back.

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,547
    edited February 2019
    Our local water department changed the disinfectant they add to the water from chlorine to chloramine (a chlorine/ammonia compound). The ammonia breaks down rubber, affecting various parts of a plumbing system (toilet flappers, faucet/water heater connectors, etc.); symptoms are like yours. Chloramine resistant fittings are now available.

    What part of the country do you live in? Check with your water department.
    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
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,948
    Hello, If you have any braided stainless flex connectors, they often have a black rubber lining that disintegrates just as you have described. An expansion tank could be another source of rubber too. ;)

    Yours, Larry
    Intplm.CanuckerFredoSP
  • luckyroy2070
    luckyroy2070 Member Posts: 5

    Hi cry1130, we have Navien water heater and having the same issue as yours. Can you please help me letting know what the issue was and how it was fixed ? It would be huge help as we are in great stress due to this issue. Thank you.

  • Greening
    Greening Member Posts: 37
    https://forum.heatinghelp.com/discussion/comment/1553825#Comment_1553825

    Who promoted those chemicals, the local plumbers union?

    The insurance companies are going to have a field day. . .or rather a flood day.

  • Jamie Hall
    Jamie Hall Member Posts: 26,350
    https://forum.heatinghelp.com/discussion/comment/1810256#Comment_1810256

    No. The public health people. The objective of the exercise is very simple: keep enough disinfectant active in the system, even at the far ends of the system, to kill any bacteria which might get in there. Such as cholera, typhoid, Legionnaires', assorted other nasties.

    Chloramines are one choice. Chlorine (sometimes as a gas, sometimes as sodium hypochlorite) is another. Which to use depends partly on cost, partly on operating safety (chlorine gas is toxic, of course — but sodium hypochlorite is a powerful oxidizer, and is a real fire hazard; chloramines are pretty safe to handle), and partly on source water quality (some source waters react to make bad tastes or odours with chlorine, but not with chloramines).

    If there were no possibility of contamination after leaving the treatment plant, then ozone, or ozone in combination with ultraviolet, could be used as a disinfectant. Unfortunately, experience has shown that public water supplies will get contaminated. Not that often, but it does happen, so a residual disinfectant is the only realistic option.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • luckyroy2070
    luckyroy2070 Member Posts: 5

    can some please help me with this ? It’s becoming huge issue for us and no one is able to figure out

  • luckyroy2070
    luckyroy2070 Member Posts: 5
    https://forum.heatinghelp.com/discussion/169518/black-particles-in-water-navien-tankless-water-heater-to-blame

    Any update ?

  • bosch
    bosch Member Posts: 3

    I have a Bosch tankless hot water heater was installed in 2021 that has black in the coming from plastic inside the hot water heater disintegrating faulty parts trying to get Bosch to admit that there’s a problem. We have MWRA water where I live. It’s an excellent source of water so the water is not the problem. It’s the hot water heater. I also have neighbors that have the Bosch hot water only two years old and it has already started with black specs.

    IMG_2662.jpeg
  • mattmia2
    mattmia2 Member Posts: 14,125

    what is the chloride content of the water and what does the manual for the tankless spec as a maximum?

  • Jamie Hall
    Jamie Hall Member Posts: 26,350

    You need to do the necessary research to determine that the problem is an inherent problem in the unit and identify the problem, and not the result of any of a host of other causes. It's called proof — and they aren't going to do it for you.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Intplm.
  • hot_rod
    hot_rod Member Posts: 25,648

    Maybe start a water analysis, then a filter on the incoming water to eliminate that potential.

    You could send a sample of the particle to a lab for an analysis, that should answer the question of how and why.

    I can't imagine a company like that not knowing what type of rubber and composite seals to use for US water?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,948

    Hi, Roughly two questions… Do those specs smear on the sink if you rub them? What sort of connectors do you have hooking up the heater? Are they braided stainless?

    Yours, Larry

  • bosch
    bosch Member Posts: 3

    I talked to the water department superintendent where I live and he said there is no reason the water should be corrodingparts in the tankless hot water heater. And yes, the. Black particles smear when you rub them. My plumber has done a flush of the system and changed out some of the plastic parts it only helped for a short time.I am going to have to put in a spin down filter that goes on after the hot water heater to collect the particles before they get to my faucets.

  • pecmsg
    pecmsg Member Posts: 6,452

    a fine strainer with a blow down might be better.

    I would still get an independent water analysis performed.

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,948

    Hi, Those braided stainless lines often have black rubber liners, which decompose and give exactly what you're seeing.

    Yours, Larry

  • bosch
    bosch Member Posts: 3

    Bosch plastic inside parts are made in Turkey. Not sure what the quality control is like there?

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