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Thread: Low HW pressure on Tankless System

  1. #1
    DIY Member gmrules's Avatar
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    Default Low HW pressure on Tankless System

    I have Nortiz Tank less HW system in my house till recently I had good HW pressure, Now when I turn on more than 1 facet have little to no pressure.

    I am on a private well who water is little hard and I do get calcium build up on the show heads and the tiles and the toilets do show the brown / orange stains

    Today I cleaned out the strainer on the cold water inlet to the unit hoping that would be my problem but it was not.

    I am suspecting the heat exchanger needs to be flused and cleaned out with like CDR or something like that to de-scale it.

    Am I on the right lines or completely off base?

    any ideas or feedback would be greatly appreciated

    Thanks
    george

  2. #2
    TROJAN WORLDWIDE SALES RP MACPLUMB 777's Avatar
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    Exclamation Low Hw Pressure



    YES MERRY CHRISTMAS;

    DO NOT USE CRL;


    you need something safe for drinking water, ie; potable water,
    use eather white vinger or AO SMITH sales a food grade acid to flush though
    the heat exchanger this may several passes to clear out the lime buildup

    then flush with clear water a couple times before putting back into service

    JERRYMAC MASTERPLUMBER PH.D WATER HEATEROLGY

  3. #3
    Licensed Grump GrumpyPlumber's Avatar
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    Two other items, check the cold inlet for a screen...you might just have sediment clogging it.
    If the GPM rating is 3 GPM or less, it's the flow restrictor...which means your unit is undersized.
    You should do a vinegar flush at least once a year, depending on your water content.
    "The biggest regrets we have in life are the chances we never took."

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    DIY Junior Member gmt's Avatar
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    I concur with the two posts above.

    Additionally, it may be undersized and is compensating for keeping the water temperature at the desired setting. Some of the units will restrict the flow in order for it to get the water warmed up to the required temperature.

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    Plumbing Contractor srdenny's Avatar
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    From my experience with Noritz, I'd say it's the screen on the cold inlet.

  6. #6
    Master Plumber master plumber mark's Avatar
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    Talking How old a Nortiz??

    I am not starting trouble here...

    but I would be interested in hearing how hard the water is??

    wether they have a water conditioner or not.??


    and how long has this tankless heater has been installed??


    If the filter is jsut the only problem you will be lucky

    If it needs to be de-limed , then it is something you
    will have to do "every so often"


    that is what I am curious about...

  7. #7
    DIY Senior Member construct30's Avatar
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    Master plumber mark is possibly correct. Fix the problem not just the symptom.

  8. #8
    Plumbing Contractor srdenny's Avatar
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    Deliming with CLR is not too difficult if you have these installed on your heater.
    Attached Images Attached Images  

  9. #9
    Master Plumber master plumber mark's Avatar
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    Talking Sr Denny...

    those isolator valves are aobut 100 bucks and should
    be installed at the time of the original install....


    what do you charge to de-lime a tankless heater????

  10. #10
    Plumbing Contractor srdenny's Avatar
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    I haven't had to do it, yet. But I've got a Zoeller dewatering pump, hoses, bucket, and a bottle of CLR ready to go when the first call comes. I figure it should take about an hour w/a little travel time added in ($150.00). As for the $100.00 cost for the iso valves, they come with a pressure relief port and a pressure relief valve. Add that to the valve you would have had to put on anyway and the true cost comes down to about $60.00. Plus, they install quickly. I usually put in the bigger units, so an $100.00 really isn't an issue, especially when you consider the cost of the Cat III flue pipe.

  11. #11
    DIY Member gmrules's Avatar
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    Default Low Water Pressure

    Thanks all that replied, to answer some of your questions

    Its a Nortiz N-084m (LP)
    Its in 3 1/2 Years
    Water Kinda Hard Just happen to have the
    water tested by the county

    Calcium 30.0
    Chloride IC: 40
    Cooper <.05
    Iron : <.10
    Hardness :as CaCO3 (Ca,MG) 101
    Magnesium 6.4
    Manganese : <.03
    Lead <.005
    PH 7.4
    Zinc .97

    I do get build up at the shower head of the white crap

    I do not have the isolating values installed, I was wondering if I could do this

    The heater is sweated in BUT, it converts back to PEX in my crawl which I can stand up in, so I wanted to install isolating values on the PEX Like so:


    Heater ------- Tee -- Ball Value -- House
    |
    |
    Ball Valve

    Do this on both Hot & Cold, Would that not Isolate the Tank so I can de-scale it?

    Where could I get Food grade vinegar? How long do I run the pump to clean and then to flush?

    I am sure this is the issue. I did clean the screen was not too dirty BTW,

    Thanks so so much Happy New Year

    George

  12. #12
    Licensed Grump GrumpyPlumber's Avatar
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    Valve on cold only.
    Put a draw off between the cold valve and the inlet, then a draw off on the hot side, no valve.
    "The biggest regrets we have in life are the chances we never took."

  13. #13
    In the Trades Bob NH's Avatar
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    You get food-grade vinegar at the grocery store. You can probably get gallon size at some of the warehouse outlets.

    It works better if the vinegar is hot. Put a couple of gallons in a bucket and pump from the bucket. Dump the return in the bucket and keep it hot.

    I don't know a good way to measure when it's done. It only takes about 5 minutes to clean a really bad teakettle but that is with the vinegar boiling. I suspect that it will take longer with a water heater.

    You can probably save the vinegar for a second time.

  14. #14
    Plumber Cass's Avatar
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    Based on the cost of vinegar I would toss it.

    Phosphoric acid or citric acid will work also, flush well with water when your done, 3-4 times, B 4 placing it back in service.
    Last edited by Cass; 12-30-2007 at 04:40 AM.

  15. #15
    DIY Member gmrules's Avatar
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    If I do not put a valve on the hot side how can I isolate it and recover / recirculate?

    George

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