Sediment in hot water lines with tankless heater

Discussion in 'Tankless Water Heater Forum' started by ryguy, Dec 10, 2009.

  1. ryguy

    ryguy New Member

    Messages:
    4
    Location:
    Tucson, AZ
    I have been having problems with sediment (looks like large pieces of sand and tiny rocks in varying colors of brown and black) accumulating in my faucet aerators and shower heads. I installed a whole house filter at the water main thinking that the water coming into the house was simply "dirty". Then I cleaned all the aerators in the house, and even decided to clean out the lines for my washing machine. That's when I realized the problem is with my hot water only, because the cold line to the washer was super clean but the hot water line was full of the sediment. It is so bad at this point that I am cleaning out aerators on a weekly basis, otherwise there is no pressure or hot water at the faucet or shower head. The washing machine keeps giving me an error code becaue the hot line is full again and no hot water is getting to it. I have an electric tankless water heater and I thought that there wasn't supposed to be any sediment with a tankless heater. My home is less than five years old and I live in Tucson, Arizona. The water has been tested and the hardness is less than 10. Anyone have any idea what is causing this problem?
  2. Dana

    Dana In the trades

    Messages:
    3,028
    Location:
    01609
    Accumulated crud in the lines keeps moving?

    Deteriorating galvanized plumbing?

    Whatever it its, it's not the tankless, which has extremely low water volume. It might lime up and restrict flow in hard water areas, but it can't develop a layer of sludge the way tanks sometimes do.
  3. AAnderson

    AAnderson In the Trades

    Messages:
    36
    Location:
    Aptos, CA
    sediment from tankless hot water heater

    All tankless manufactures recommend softeners if the water has more than 11 grains of hardness (roughly 210 ppm total dissolved solids). Calcium will precipitated out in hot water which is why you are experiencing the debris you are in appliance pre filters and aerators...
  4. macmikey

    macmikey Macintosh Computer Consultant/Tech

    Messages:
    4
    Location:
    Phoenixville, PA
    Have Rinnai Tankless and sediment also

    My plumber said it was from the old tank heater and the crud it created.

    He comes out, on schedule, to flush the system, run a vinegar solution through it and then flush it again. He also replaces my whole house filter and maintains the faucets for me as well.

    I go around about every 2 weeks or so and clean out all of my faucets and other filtery kind of things to prevent blockages.

    The routine maintenance is required for the warranty on the Rinnai or you may not get service on it. It does not reduce the crud, but does guarantee that the heater itself is not going to be damaged by it.

    Mike
  5. AAnderson

    AAnderson In the Trades

    Messages:
    36
    Location:
    Aptos, CA
    Mike, define crud? Do you mean small white particles that looks like broken sea shells? This is calcium that has precipitated out of solution under heat and pressure, a problem is you have hard water. A whole house filter will not remove dissolved solids.
  6. 4fuzzies

    4fuzzies New Member

    Messages:
    2
    Location:
    Durham, NC
    I'm a little worried since this thread was posted in 2009 and there doesn't seem to be a consistent answer. We too have the sediment in our hot water lines that looks like sand and up to 2mm sized pieces of mineral. We too were convinced to put a water filter on the incoming water. This did nothing for the problem and just killed our water pressure. It seems to be worse in the winter, we clean the shower head 3 times per week as apposed to once a month in the summer. Our water heater in a natural gas powered rinnai tankless that was installed in 2009. Our heat unit is an Apollo hydroheat system. We had no problems from 2005 when we moved in, until the summer of 2010. Then we lost hot water. The plumbers that put in the rinnai came out and cleaned the in line filter and the faucet aerators. We thought at the time that the sediment was from when the city changed the meters on the water lines. The problem went away until fall 2010 when the heaters kicked on. That's when we were told we need the whole house filter. It fixed nothing. We still have sediment in the lines that makes me feel like when I run the bath for my kids, I'm not getting them any cleaner. We call out plumbers... they say its the Apollo unit. We cal out hvac guys they say either they can't touch the Apollo units or its a plumbing problem, call a plumber. We have had several different companies come out. No one has an answer. We have to run the sink in the bathroom if we want to take a hot shower, otherwise because the lines and showerhead are so plugged, not enough water flows through the rinnai to turn it on. We did not have any problems the first winter after getting the new rinnai tankless. For what it is worth, our house was also plumbed using the now illegal Quest pipe. Please help. This thread is the closest thing we have found to an answer in 2 years.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    Have you demineralized the tankless system? It's fairly easy if it was setup properly with the appropriate fittings, otherwise, it can be a pain the first time (assuming you install them now). This involves pumping a weak acid solution through the thing for a period of time to disolve the minerals. Depending on the hardness of your water, your total water use, and how hot you have the tankless set would all affect how often it needs to be done. The internal passages could be restricted a lot, and the minerals also act like an insulator. Depending on the heating, some could break off during use and may be the source of the mineral chunks.
  8. 4fuzzies

    4fuzzies New Member

    Messages:
    2
    Location:
    Durham, NC
    Thanks Jadnashua, I will ask the installing company when they call me back. I forgot to mention that we did have 1 plumber (who was out for a busted pipe) tell us how to flush the water lines by draining the lines and then flushing water into them and turning the faucets on 1 at a time. We have done that 4-5 times since December. The first flush maybe seemed to help some, but I have not really been able to tell any detectable difference with the subsequent flushes.
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    That will only dislodge or flush loose stuff...that is totally different than what I'm talking about. Basically, you turn the heater off, disconnect the lines (or if you already have flush valves installed, switch them to flush position), then you use a pump and a hose and a couple of buckets to run acid through the heater. This disolves the caked on mineral deposits that are in the thing. WHen done (might take a hour or so), you reset the lines to 'normal' and flush the thing out from the acid, then you can turn the heater back on. The exact procedure depends on what fittings and valves you have, and how you need to make it all work. From what I remember, Tucson doesn't have the greatest water (really hard!), so you should plan on doing this probably at least once a year. Someone who knows how to service this type of heater will be able to advise you on how to maintain it properly.
  10. andream

    andream New Member

    Messages:
    2
    Location:
    Austin TX
    ryguy, I wonder if you have ever resolved this issue, or if anyone has figured out how to.
    We have 2 Noritz tankless water heaters in a 5 year old house. Over the past few years we have had many problems with water pressure and clogged aerators. We finally had plumbers install flush kits on our heaters and have since flushed them 3x, 2x with vinegar and the last desperate time with CLR. Still there is sediment in the hot water lines. I contacted Noritz and they suggested we need a water softener. We really don't want to take the minerals out of the water or put in an expensive purification system. We are considering a post-heater sediment filter and wonder if anyone has done this and if it will work. I don't mind cleaning out the sediment once in a while to stop it from reaching our dishwasher or washing machine which has resulted in some expensive repairs.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    FWIW, you can connect a water softener so that it only conditions water going to the heater. That way, you'd still have the minerals in the cold taps. Because the volume through it would likely be less, you'd use less salt verses conditioning all the water to the house.
  12. andream

    andream New Member

    Messages:
    2
    Location:
    Austin TX
    Thanks for the tip. I'll suggest it to the plumber.
  13. lifespeed

    lifespeed Member

    Messages:
    333
    Location:
    California
    We get minerals from our food, minerals in the water are a gnat's eyelash. As you have learned, hard water is damaging to your plumbing and appliances long-term, making a softener a good investment. I like to add an under sink RO filter for drinking water.
  14. bookemdanno

    bookemdanno New Member

    Messages:
    5
    Location:
    Ohio
    Why spend the money on a water softener only to not enjoy it's benefits on the cold water as well?
  15. lifespeed

    lifespeed Member

    Messages:
    333
    Location:
    California
    ^^ +1

    Softened water is great. If you're going to pay for it, run it through both hot and cold pipes. I like RO for drinking water, feed an undersink unit with softened water also and use the RO model with a permeate pump.
  16. Asheville_jeff

    Asheville_jeff New Member

    Messages:
    1
    Location:
    Asheville, SC
    Seeing a similar issue on a recent install of a tankless water heater. I'm considering putting a whole house filter after the tankless to capture precipitate.

    1 Any idea on how quickly this would get clogged?

    2 would/should I flush the lines / heater first

    3 is there build up in the tank as well (I've seen several threads that indicate there is either build up in they tank or in the lines - not sure if this based on the type of heat exchanger - but that's my guess)

    Many thanks
  17. aross8687

    aross8687 New Member

    Messages:
    1
    Location:
    Chapel Hill, NC
    Hello. I hope you have resolved your issue by now 4fuzzies. We just had the exact same problem (Well, I say that not knowing precisely what the sediment in your line looked like.) We noticed the other day that there was sediment in the hot water line coming from the tankless (Rinnai brand) water heater. It is only 2 years old. We have another water heater in the house and all the lines connected through that were fine so we knew it wasn't dirty water coming in the house. We finally discovered that the problem was with the expansion tank that was connected to the tankless heater. When the old water tank was removed a couple years ago, the contractors chose not to replace the existing expansion tank. Well, apparently, the expansion tank has a bladder and perhaps because of the cold weather it had cracked. It was essentially disintegrating and entering the water stream. Expansion tank replaced = no more sediment. I'd love to know if your solution, assuming you found one, was the same. Good luck!
  18. Bluetruck07

    Bluetruck07 New Member

    Messages:
    1
    Location:
    MN
    Tankless Water Heater Sediment

    HI, I've been reading everyone's issues with the tankless heaters. I was going to get one until a friend of mine installed one without a softener and he had the same issue, hard mineral chunks only coming out of the hot line. After finding out from the mfg that sometimes this technology can nucleate boil (momentary boil) the water running through it which bakes the minerals, he simply installed a hot water sediment filter (I think it was a Rusco brand) after the boiler and a HydroFlow S38 on the incoming water source to treat the entire home, no softener needed. The HydroFlow will prevent scale buildup and keep appliances running smoothly. I love being green when it actually works. Now that I know how to deal with it, I'm going to get one.
  19. Leon82

    Leon82 New Member

    Messages:
    7
    Location:
    CT
    The rusco filter is next on my list. I descale twice a year with flowaide solution or white vinegar.

    I think most of my particles were from a worn annode in the mini tank i buffer and resirc with.
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