Low HW pressure on Tankless System

Discussion in 'Tankless Water Heater Forum' started by gmrules, Dec 28, 2007.

  1. gmrules

    gmrules New Member

    Messages:
    94
    Location:
    Raleigh NC
    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. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Low Hw Pressure

    :D

    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:D

    JERRYMAC MASTERPLUMBER PH.D WATER HEATEROLGY
  3. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    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.
  4. gmt

    gmt New Member

    Messages:
    26
    Location:
    Pennsylvania
    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.
  5. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    From my experience with Noritz, I'd say it's the screen on the cold inlet.
  6. 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...
    Last edited: Dec 28, 2007
  7. construct30

    construct30 New Member

    Messages:
    590
    Location:
    NorthWest PA
    Master plumber mark is possibly correct. Fix the problem not just the symptom.
  8. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    Deliming with CLR is not too difficult if you have these installed on your heater.

    Attached Files:

  9. 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. srdenny

    srdenny Plumbing Contractor

    Messages:
    361
    Location:
    SF Peninsula
    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. gmrules

    gmrules New Member

    Messages:
    94
    Location:
    Raleigh NC
    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. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    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.
  13. Bob NH

    Bob NH In the Trades

    Messages:
    3,317
    Location:
    New Hampshire
    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. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    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: Dec 30, 2007
  15. gmrules

    gmrules New Member

    Messages:
    94
    Location:
    Raleigh NC
    If I do not put a valve on the hot side how can I isolate it and recover / recirculate?

    George
  16. Exactly how long a process is this????

    How exactly do you know when you have
    flushed out these things anyway????

    When do you know you are back to max efficiencey again???

    I mean, do you get a murkey , frothey kind
    of chicken soup thing going in the vinegar after
    about a half an hour

    or are you supposed to let the vinegar sit still in
    the exchanger for a 15 minute period then flush it out
    and repeat the process over and over agian till the

    vinegar looks nasty????
  17. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    A pump into the cold with a return off the hot side...as long as all hot fixtures are closed you're fine, though it will go into the hot line a bit...the flush has nowhere else to go.

    Also, another effective cleaner, DON'T laugh...unsweetened concentrated cool aid.
    It has citric acid, as Cass states above.
  18. gmrules

    gmrules New Member

    Messages:
    94
    Location:
    Raleigh NC
    Thanks all for you r advise

    I will be doing it this weekend
  19. again...when do you know its cleaned out good enough???

    No one cared to answer my queston...

    perhaps it was s stupid one, perhaps not.....


    How long a process is this and how or when do
    you know that you are back to 98% eff again??
  20. gmrules

    gmrules New Member

    Messages:
    94
    Location:
    Raleigh NC
    Sorry Mark

    According to Nortiz 45 mins you need to circulate the solution

    I was expecting a more experienced person to answer :)
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