Low HW pressure on Tankless System

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

  1. gmrules

    gmrules Member

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    So Sorry for the delay in the update, I had both my knees replaced been layed up

    Was semi successful in the de-limeing, works better but not 100%

    Will get back to it when I am recovered

    thanks for all your help everyone

    George
     
  2. GrumpyPlumber

    GrumpyPlumber Licensed Grump

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    Plumber, self employed
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    Thought this thread a good place to post this...
    Got a call from a customer I installed a tankless for over 1-1/2 years ago...LOL.
    "I...um...think you'd mentioned we're supposed to flush this thing once a year, I forgot how you said to do it...any chance you could do it?"

    I go over and show him how to set up the pump, flushed it with 3 gallons of vinegar ($2 a gallon at Costco).
    I let it run for a full hour and..HOLY MOLY...it was BLACK!

    For those of you who own them, it's VERY simple to do, no parts to be removed - they get cleaned as well, plug & leave, come back an hour later and thats it.
    Nothing complicated, no serious issues, just a small pump with two double ended washing machine hoses connect the the cold inlet draw-off, close the cold valve and let it circulate the vinegar through the hot draw-off through a 5 gallon bucket while you get on with life for an hour or so.
     
  3. gmrules

    gmrules Member

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    Its back

    WELL here I am in the same BOAT very LOW pressure through my unit

    I have date with my vinegar tonight
     
  4. gregsauls

    gregsauls Homeowner

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    Texas
    I bought a little pump from Harbor Freight that powers off a drill. Works great for less than $10!
     
  5. Ladiesman271

    Ladiesman271 Homeowner

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    That earlier Grumpy Plumber post goes back to 2008.

    Pool cover pump
     
  6. Ladiesman271

    Ladiesman271 Homeowner

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    Occupation:
    Care and maintenance of transformers


    Check the water heater inlet filter once a year. If that is clogged up, that creates a flow problem. Flush / descale should be also be performed once a year.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The inlet filter condition has little relation to how much, if any, mineral deposits are in the heat exchanger. The filter is catching sand, and other crud that may be in the inlet water, not minerals, unless they are already precipitated out of the water. Think tea kettle...it WILL get mineral deposits in it unless you use softened water through it.
     
  8. Ladiesman271

    Ladiesman271 Homeowner

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    While that is true, my response was to these words:

    "WELL here I am in the same BOAT very LOW pressure through my unit".

    Check first things first is my procedure. Note that I also recommended an annual descale. Just because you descale does not mean that the filter is clean. A somewhat clogged tankless water filter will reduce water flow everything else being equal. With a somewhat clogged inlet filter, it is also difficult to descale in a reasonable amount of time anyhow (AKA low flow).
     
  9. SewerRatz

    SewerRatz Illinois Licensed Plumber

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    Chicago Illinois Licensed Plumber
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    Chicago, IL
    The joys of a tankless unit. Be right back I need to check the inlet filter on my tanked unit... oh wait there isn't one.

    This is the other issue about tankless units they do need to be maintained and will show signs of neglect faster than a tank unit. This is why I explain to whom ever calls me to install one of these that they must commit to maintaining it on a regaler basis.

    Now that I got my little rant out of my system. Yes I would check the inlet filter if your unit is so equipped. Once you verify it is clean, then proceed to delime it. Instead of vinegar A.O. Smith makes a product called Un-Lime that works great, the even have a pump kit for coil type heaters which is another type of heat exchanger. Part number for this pump is Parts No. 4930 and the part numbers for the solution is PART NO. 4763-P4 (1 Gal. Size, case of 4)
    PART NO. 4813 (5 Gal. Size)
     
  10. Ladiesman271

    Ladiesman271 Homeowner

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    I guess that you forgot about the maintenace schedule on tank type water heaters. Did you ever take the A.O. Smith tank water heater maintenance training course?


    Is regular monthly draining of a tank type water heater required? Yes!

    Is deliming required in a tank type water heater? Yes!

    Is anode rod inspection / replacement required in tank type water heater? Yes!

    Is your warranty void if you do not descale a tank type water heater on a regular basis? Yes!



    A.O. Smith Tank Water Heater Maintenance Requirements


    PRESENTED AS A SERVICE TO THE PLUMBING TRADE BY

    A.O. Smith Water Products Company


    For many years the importance of establishing an effective preventive maintenance recommendation for tank type water
    heating equipment has been recognized.
    Due to a combination of factors, including limited tank access and lack of
    suitable scale removal products, such a program had not been developed. In addition, the low input, small tank size
    heaters of the past operated in a generally satisfactory manner for long periods of time with little or no attention.

    With the advent of higher input, larger tank size heaters in both commercial and residential models, maintenance has
    become a problem that must be faced and dealt with to obtain maximum unit life and user satisfaction.



    When

    Aside from monthly tank flushing performed by opening the
    drain valve (with the water inlet valve left open to maintain
    pressure in tank), and allowing the water to flow until it runs
    clean; maintenance should be as indicated until experience
    indicates the interval for a given operation should be
    changed ...to a shorter or longer interval.

    Changes in water hardness, hot water usage and outlet
    water temperature may affect the lime buildup in the heater
    or on the elements. Therefore changes in any of these
    factors may require deliming to be done on a different
    schedule.


    Gas and Oil-fired Units

    The depth of lime buildup should be measured periodically.
    Heaters equipped with cleanouts will have about 2" of lime
    buildup when the level of lime has reached the bottom of
    the cleanout opening. Heaters without cleanouts will have
    about 1" of lime buildup if it has reached the drain valve
    opening. A schedule for deliming should then be set up,
    based on the amount of time it would take for a 1" buildup of
    lime. It is recommended that the water heater initially be
    inspected after 6 months.


    Example 1:

    If initial inspection after 6 months shows 1/2" of lime
    accumulation. Therefore, the heater should be delimed once
    a year.


    Example 2:

    If initial inspection after 6 months shows 2" of lime accumulation.
    Therefore, the heater should be delimed every 3 months.


    Electric Units

    A hissing sound may be heard as lime scale builds up on
    the residential water heater elements. When this is noticed,
    the elements should be removed and delimed.

    Commercial water heater elements should be delimed as
    determined by periodic inspections. If elements are limed,
    a shorter interval between inspections should be scheduled.



    Anode Rod Inspection

    The anode rod is used to protect the tank from corrosion.
    Most hot water tanks are equipped with an anode rod. The
    submerged rod sacrifices itself to protect the tank. Instead
    of corroding the tank, water ions attack and eat away the
    anode rod. This does not affect the water’s taste or color.
    The rod must be maintained to keep the tank in operating
    condition.

    Anode deterioration depends on water conductivity, not
    necessarily water condition. A corroded or pitted anode rod
    indicates high water conductivity and should be checked
    and/or replaced more often than an anode rod that appears
    to be intact. Replacement of a depleted anode rod can
    extend the life of your water heater. Inspection should be
    conducted by a qualified technician, and at a minimum
    should be checked annually after the warranty period.

    NOTE: Anode rod inspection may need to be made
    more frequently in areas subject to acid rain that obtains
    their water supply from surface water as the low pH
    will accelerate anode activity.


    .
     
    Last edited: Feb 17, 2009
  11. SewerRatz

    SewerRatz Illinois Licensed Plumber

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    Chicago Illinois Licensed Plumber
    Location:
    Chicago, IL
    Did you take the course? Also did you take any of the tankless water heater courses. I have and I have the certificates to prove it. My point of my little rant is most people do not do the maintenance required on a tanked heater mainly since they do not notice that it is not preforming as well as it used to. If they did half of what is recommended, it would last much longer. The trouble is if you do not maintain a tankless unit you will see a fall off water pressure, and or how hot the water actual gets.
     
  12. Ladiesman271

    Ladiesman271 Homeowner

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    Care and maintenance of transformers


    Yes, but can anyone afford to have a professional do regular maintenance on a tank type water heater? That tank deliming procedure is kind of dangerous for a DIYer!

    For that matter, does anyone do any maintenance on a tank water heater unless it does not work at all? Out of site and out of mind? It is probably just cheaper to replace the tank every ten years than to pay to have PM performed on a regular basis.


    Yes, if you want a tankless heater to last 20 years delime it on an annual basis!
     
  13. SewerRatz

    SewerRatz Illinois Licensed Plumber

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    Occupation:
    Chicago Illinois Licensed Plumber
    Location:
    Chicago, IL
    Was the first yes that you took the A.O. Smith course?

    All un-lime is phosphoric acid solution, same stuff in your soda pop. As long as you remove the anode rod deliming it is a whole lot easer than some of these projects these DIYers take on. The instructions for deliming a tank heater is real easy to follow. http://www.hotwater.com/lit/training/4800r9.pdf
     
  14. Ladiesman271

    Ladiesman271 Homeowner

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    Aug 22, 2008
    Occupation:
    Care and maintenance of transformers


    That's the same link that I used in my post above. Too bad those anode rods do not come out that easy, and you do need some clearance above the heater to get the anode out of the tank.


    Any homeowner can descale a tankless with little effort and for little cost. No need to call in a professional to do a descale on a tankless.


    My basic point was all water heaters require routine maintenance. I have no objection to the use of either a tank or tankless water heater!
     
  15. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Joined:
    Nov 20, 2008
    Occupation:
    Chicago Illinois Licensed Plumber
    Location:
    Chicago, IL
    And my point is a tanked heater with out the maintenance still provides water pressure and hot water. The thing is it may fail prematurely and consume more energy to keep the water hot when it has not been maintained. Where as a tankless that is not maintained people will notice the water is not as hot, or the pressure gets really low.
     
  16. nhmaster

    nhmaster Master Plumber

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    Tech. Instructor
    Location:
    S. Maine
    I have a 40 gallon AO Smith electric water heater that has been running continuously for over 15 years now with ZERO maintainance, not even an element. And that is not unusual for water heaters at all. Hardly anyone ever services them with the exception of changing elements. Original cost of the tank, around 150 dollars back then.
    Though you probably should do periodic maintainance on them, mos folks never do. They will not get away with the same careless attitude with their tankless.
     
  17. Redwood

    Redwood Master Plumber

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    Dec 15, 2007
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    Service Plumber
    Location:
    Connecticut
    What's that matter to you?
    You couldn't even afford to have your tankless installed by a pro in a state that has laws prohibiting DIYer Plumbing in addition to voiding your manufacturers warrantee...

    That is why I install Bradford White Hydrojet Water Heaters...

     
  18. STyler

    STyler Member

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    Sep 9, 2009
    Location:
    Rock Hill, SC
    Can you explain with a little more detail (for a novice) how the unit should be plumbed to accommodate the process the easiest? I was planning on going from Pex > ball valve > Flex WH pipe > Cold Inlet. Is the "draw off" a "T" after the valve with a another ball valve that terminates to nothing (to be tapped into for the flush)?

    ... and then the exact same setup on the Hot Water outlet?
     
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