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Tankless Scale Removal

RickDelta
RickDelta Member Posts: 483
edited November 17 in Domestic Hot Water

Hello HeatingHelp.com community! : )

In a commercial hot water (potable) tankless environment (high volume), the need can be as short as every three months to vinegar wash out the system. Scale build up servicing is mandatory for heat exchanger warranty coverage.

It is my contention, that the use of a cold water inlet pre-treatment with a TAC (Template Assisted Crystallization) filter would then negate the required vinegar flush entirely and preserve the covered manufactures warranty.

……. thoughts on this?

Comments

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,576

    Hi, I found this article: https://waterfilterguru.com/what-is-template-assisted-crystallization/#:~:text=Learn%20what%20%EE%80%80TAC%EE%80%81%20is, They suggest TAC can reduce scale buildup by 90%, so you would still need periodically to descale the heater. If your heater has any way (maybe with a boroscope) to have a look inside of the heat exchanger, it would be useful to really know how well the TAC unit is working. Seems that as long as you can demonstrate that the heat exchanger has never been fouled, warranty on the tankless heater should remain in force. 🤓

    Yours, Larry

    RickDelta
  • RickDelta
    RickDelta Member Posts: 483
    edited November 16
    TAC-element1.png

    @Larry Weingarten

    Thanks Larry!

    My thoughts are that if it stops the scale minerals from attaching in the first place "AND" ……… removes any scale that had already established itself to the heat exchanger , that there should not be any significant scale left. (hence no need for a vinegar wash)

  • RickDelta
    RickDelta Member Posts: 483
    edited November 16

    ……… pondering:

    Where you normally connect to the vinegar "flush" ports , a small circulator to act as a TAC "scale scrubber" loop during idle flows 24/7 ? (no vinegar)

    The same loop could "scrub" all heat exchangers, even in a large commercial 24 unit tankless group.

  • Revenant
    Revenant Member Posts: 45

    Calcium and magnesium are inversely soluble in relation to temperature.

    Therefore calcium and magnesium will plate out (scale) on hot surfaces.

    Sodium is increasingly soluble in relation to temperature.

    Sodium will not plate out on hot surfaces.

    So trade the calcium and magnesium with sodium before sending the water through the water heater.

    Do this with a basic old fashioned sodium ion exchange water softener.

    Good for water heaters, bad for boilers.

    Bad for boilers because boilers are hotter. Sodium raises the electrical conductivity of the water and causes corrosion at the higher temperature of the boiler. No problem in the lower temperature of the domestic water heater.

    RickDelta
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,576
    edited November 16

    Hi, I'll throw in that salt softened water is good for water heaters in that it slows sediment build-up in tanks, but bad for water heaters in that it increases conductivity of the water, accelerating sacrificial anode consumption. I've seen anodes completely used up, down to a bare wire, in six months with softened water. So, there is a balance to be found.

    Yours, Larry

    ps. I'll add that whatever is done with TAC, it would be really useful to be able to do a visual inspection, so you know what's going on.

    Revenant
  • RickDelta
    RickDelta Member Posts: 483
    edited November 17

    @Larry Weingarten

    With the relatively small heat exchanger surface area of a tankless unit ….. I was amazed of just how fast you lose this high efficiency to scale accumulation.

    Scale Loss.png

    Its my contention that removing the scale build up, at its earliest formation, before it has a chance to drop its heat transfer efficiency ……….. is to perpetually "scrub" the heat exchanger of the scale minerals during its no-flow idle state.

    I'm installing a new "Quad" tankless group in about three weeks at one of our motels.

    In prima facie …..

    I think I can easily form a closed recirculate loop (aka: keep alive loop) from the cold water TAC filter and the "flush" ports on all four of the tankless units isolated with spring loop checks. Control the scrubber circulator with the tankless own flow detector.

    Scrubber2.png

  • hot_rod
    hot_rod Member Posts: 23,249
    edited November 17

    we make these phosphate dosers for residential tankless and combi boilers

    You could probably find or make something similar

    https://www.caleffi.com/en-int/under-boiler-polyphosphate-dispenser-5459-caleffi-545950

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    RickDelta
  • RickDelta
    RickDelta Member Posts: 483
    edited November 17

    @hot_rod

    Hi Hot rod! : )

    What's the working principal of this unit? (didn't get much from the link)

    Despite the benefits, excessive use of PolyPs in food products can increase potential health concerns. Kidney damage, cardiovascular issues, and weakened bone due to calcium-phosphate imbalance are some of the potential consequences (Calvo & Uribarri, 2013; Kemi, Kärkkäinen, & Lamberg-Allardt, 2006).

    This unit "doses" polyphosphate crystals that dissolve and mix into the water??

  • hot_rod
    hot_rod Member Posts: 23,249
    https://forum.heatinghelp.com/discussion/comment/1820754#Comment_1820754

    There are pros and cons to all the various treatments for water. Ion exchange softening, TAC, phosphates, RO,

    We looked at bringing these phosphate dosers to the US market, but the capacity seems far too small for typical US water users.

    Tap water is very expensive in Europe, they tend to use much less.

    Research and find the water treatment method(s) that you are comfortable with.

    Screenshot 2024-11-17 at 12.12.54 PM.png

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    RickDelta

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