Controlling Final Hardness, salt dosage, upflow brining questions

Discussion in 'Water Softener Forum, problems, installation and r' started by cgarai, May 12, 2012.

  1. cgarai

    cgarai New Member

    Messages:
    21
    Location:
    Sonoma County
    A couple of questions:

    1. I am wondering how to adjust the final hardness of softened water. The reason for this is that I am installing a condensing water heater that requires that hardness be maintained between 5 and 7 gr/gal. I am starting with water that is 13 gr/gal. I have read that reducing the salt dosage allows the final hardness to be above 1 gr/gal, but it is not clear to me by how much.

    2. I understand that SFR is 7gpm/cuft. (although I have seen references to it being non linear). How does one avoid channeling? Is there a minimum flow/cuft? I assume that channeling doesn't occur just because a low flow is being demanded over the short term (a single low flow tap on for 2 minutes). It must occur over a longer time if insufficient peak flow rates don't occur often enough.

    3. How does softening affect TDS?

    4. I have read much about salt dosage and brine efficiency, but I don't understand how to set it up. I don't see mention of salt dosage in the programming manuals for the 2510SXT, 5600SXT or 7000SXT. It is briefly mentioned in the 6700 Upflow manual. How is it set in these other controllers? Seems like I'm missing something.

    5. I'm not too concerned about hardness leakage if SFR is exceeded on occasion. Why is it mentioned so much? I don't see a problem with occasional briefly elevated hardness or am I missing something (again)?

    6. What is upflow brining? Is it more difficult or expensive? How much more brine efficient is it? Is it more water efficient?

    7. My intention is to use one of the above Fleck valves. Any opinions about them? I am having a hard time finding a good comparison of the features and capabilities.

    Thank you,

    Chris
  2. F6Hawk

    F6Hawk New Member

    Messages:
    166
    Location:
    Alaska
    Chris,

    With regards to #1, I'd buy a Hach 5B hardness test kit so you can test your own water. Then, if you have a triple-tree type bypass, just mix unsoftened water with softened until you raise the hardness to 5~7gpg. Trial and error on the amount to bypass, using the hardness tester.

    And for #5, I can't see it being a big issue for a home owner, either. Perhaps in commercial apps, or where equipment requirements force the user to remain under a few ppm... but if I had it in my home, I wouldn't worry, personally. I'm sure the pros can give more examples where it might matter a lot.
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,185
    Location:
    Maine
    Let's back up a second. Are you saying that the manufacturer of the water heater is looking for water hardness between 5 and 7 gpg? Or is that the maximum hardness they want water flowing through their coils because I'd bet you that the 5-7 is the maximum not the minimum in which case any properly sized softener will bring you below those numbers.
  4. F6Hawk

    F6Hawk New Member

    Messages:
    166
    Location:
    Alaska
    From http://www.pexuniverse.com/docs/pdf/takagi-t-h2-manual.pdf

    As Tom says, you are prolly looking at a MAX hardness rating, not a target. The less hardness, the better it typically is on plumbing/equipment.

    "Only potable water or potable water / glycol mixtures can be used with this
    water heater.* * Do not introduce pool or spa water, or any chemically
    treated water into the water heater.
    • Water hardness levels must not exceed 7 grains per gallon (120 ppm) for
    single family domestic applications or more than 4 grains per gallon (70
    ppm) for all other types of applications.* *Water hardness leads to scale
    formation and may affect/damage the water heater.* *Hard water scaling
    must be avoided or controlled by proper water treatment.
    • Water pH levels must be between 6.5 and 8.5
    • Well water must be treated."
  5. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,842
    Location:
    Ontario California
    #1 hardness leakege will be measured in ppm, not gpg when lower salt setting are used. FYI, 1 GPG = 17.1 ppm. The reason for caring about hardness leakage is for two primary reasons. 1: Critical low ppm hardness applications, including steam boilers, turbines, and Ultrapure EDI applications, 2, when a customer complains that the water does not "feel" soft, but the hardness is 1 or less. Water hardness at 10+ppm will often feel harder than water that is below 5 ppm. Here is a link to a recent article by an old freind. He is one of the smartest people in the water industry and he explains something very similar to this topic in this article. http://www.wcponline.com/pdf/1203Michaud.pdf

    2: Correct, softeners do have a minimum as well as a maximum flow. There is a lot more to the calculations than just Cu. Ft, we also have to consider and calculate tank diameter and it relationship to Sqare footage as well as bed depth. Many years ago, it was acceptable practice to throw in a couple of 50 cu. ft softeners to feed a hotel, now we use multiple small systems that will turn on and off to meet the flow needs. This allows for much higher efficiences, and eliminates the low flow channelling common in the older large systems. For a regular house, tank diameter should probably never exceed 16", but 14" and smaller is preferred to ensure that there will be minimal to no channelling.

    3: Softening will typically raise your tds since the exchange of sodium ions to calcuim and magnesium is not an equal exchange. This again is difficult to say for certain exactly how much the tds will rise, on paper it is easy, but in the real world, it never calculates out the way you would expect it to.

    4: Salt dosage efficiency has been discussed at great length here recently, while I do not like the answer of "use the search button", I will say it this time, or ask again later in the week and I can repost some charts. To put it simply, the lower the salt setting, the higher the hardness and the higher the water usage. Higher salt settings will use less water, and produce softer water. The industry has basically settled on 4-8 pounds of salt per cubic foot, while 4 gives fairly poor quality water, it is extremely efficient, and 8 pounds gives extremely high quality water, but you do give up some of the efficiency. It can be a personal preference thing, or it can be a regulated issue as well. In California, a salt setting of 4 pounds per cubic foot is required to meet standards, but this is not enforced. Most people in the industry set their own units to 8 pounds per cu ft for the higher quality. Anything less than 4 gives really poor quality soft water, anything above 8 pounds loses too much efficiency.

    5: SFR is generally completely overstated. You are correct that exceeding the flow rate of resin on a rare occassion is not a big deal. Leakage will increase, and possible damage to the resin can occur. That being said, it is written more for commercial applications where a known flow rate will be achievec on a regular basis. Commercial dye plants that fill a 2000 lb wash basin with a fill rate of 120 GPM, we would definetely consider the flow rates carefully and design the equipment to ensure we do not damage the resin within the first three months. Commercail steam boilers, where <3ppm is required is another example, we can not achieve a low PPM hardness count if the water flow is not considered correctly to the equipment. Residentially, if you happen to be running your mega shower with 3 body sprays at 5 gpm, and the dishwasher turns on, 1.5 gpm, a sink turns on, 2 gpm, a toilet flushes, 1.5 gpm, then the laundry kick s on, 3.5 gpm..... as you can see, even with a 1.5 cu, ft system, the chances of a house exceeding the maximum flow rate of a standard softener is almost non existent, unless you are dealing with a very considerable house. Most manufacturers now give peak flow rates since the frequency of exceeding the system maximum "recommended" flow is so minimal , you can use the peak to determine if it will meet your needs. I do regular training on this topic, and it is usually geared toward commercial and industrial applications, for residential applications, if their is any concern, it is overstated. My recommendation, assuming your hardness does not exceed 25 GPG, a 2 cu. ft 7000SXT will hadle any house that has a 1" main pipe.

    6: wow, the qestions you ask are long topic answers, but I will shorten it to this. On paper, uplflow brining is absolutely superior to downflow brining in every way. In the real world, it is a pain in the butt and is not worth the headache. We have almost eliminated upflow brining from our vocabulary since it has become more of a marketing gimmick since so few companies do it correctly anyway. Upflow brining is in no way a new idea either. Anybody here ever see or work on a schurz valve? They were bought by Fleck in the 80's I beleive, and were quickly dropped from production. That was an uplfow brining design that has been around for decades prior to being "phased out". The advantages of upflow brining are nearly eliminated unless the valve, pressure, injectors, flow controls, timing etc are all perfectly programmed and intitially set and that nothing ever changes including the resin (which changes over time) the pressure (which changes by the minute), etc. Most of the perceived advantages of upflow brining can be realised by a standard control valve with a double backwash. In other words, an extra 10 gallons of water every couple of weeks eliminates all of the potential problems of upflow brining. I am a fan of upflow brining, but I do not even stock them in our distribution facility.

    7: All of the valves you metioned are great but... the 7000SXT has all of the features of the other valves, is nema 4 rated, has far higher flow rates, uses a larger riser, has more plumbing options, and has replaced the other valves for many of the major manufacturers. The main disadvantage is that the valve itself, is HUGE. Many of our customers prefer that since it costs almost the same, and looks impressive. If you are extremly limited on space, you may want to order the 90 degree adapters to tighten the valve up a bit.

    Hope this helps.
  6. chevy427

    chevy427 Banned

    Messages:
    174
    Location:
    USA
    I have a feeling you are mistaken here about the water heaters. You don't want a softener that has a programmed failure by 'leaking' hardness. Heater companies have a maximum of 5-7 grains for usage but still prefer soft water with a pH of between 6.8 -8.5. Simply reducing the salt dosage won't lower hardness consistently over the life of the service cycle but will run out of softened water faster.

    For other applications where complete softness of water is not desired, then it is not the softener that has to be adapted, but the plumbing. But re-read you heater manual on hardness levels.
  7. cgarai

    cgarai New Member

    Messages:
    21
    Location:
    Sonoma County

    That is exactly what I am saying. And it's a stainless steel water heater as well. Here is a quote from the manual:

    "If the hardness of the water exceeds the maximum level of 7 grains per gallon, water should be softened to a hardness level no lower than 5 grains per gallon. Water softened as low as 0 to 1 grain per gallon may be under-saturated with respect to calcium carbonate, resulting in water that is aggressive and corrosive."

    You can read it here: http://www.htproducts.com/literature/lp-179.pdf

    I looked briefly into Langelier Scale Index and I sort of see why. If I plug in low numbers of hardness (.1 - .5 gr/gal) you get mildly corrosive LSI numbers. If you are really pulling all the hardness out the numbers go very negative (corrosive).

    Thanks,

    Chris
  8. chevy427

    chevy427 Banned

    Messages:
    174
    Location:
    USA
    Softening water makes the water no more corrosive than before it was softened.
    http://www.wqa.org/sitelogic.cfm?ID=366

    The manufacturer may be relating to areas in the country where natural water sources have very low pH associated with very low hardness (and low TDS), which can be corrosive. In those cases, hardness can be raised while elevating pH. I would check your pH. if it is above 7, then I wouldn't worry about corrosion.

    I mean, it is ridiculous to find a way to change hardness from 7 grains down to 5. Perhaps they are creating a situation that easily voids warranty. Check competitors' manuals and see if they recommend the same.

    I work with a restaurant that has an espresso machine that is fed by an RO. Due to its copper boiler, a calcite filter was added to raise the pH slightly.
    Last edited by a moderator: May 13, 2012
  9. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,185
    Location:
    Maine
    If I had too and I mean had too, I would leave the softener set normally and run an untreated line, tee'd into the inlet to the water heater that would allow me to add unsoftened water at that point but holy crap, what a pita that would be and you would have to test constantly to insure the level was right. I'm with Water Solutions on this one.
  10. Gary Slusser

    Gary Slusser That's all folks!

    I agree as long as the peak demand of the house doesn't require a larger softener and you can't split the flow to 2 softeners or 2 in parallel.

    Or he can click on the Click Here in my signature.

    As you know, most control valves allow for adjustment of the water use per regeneration, the same as for the salt dose. And all resin manufacturers that I've checked resin spec sheets with suggest a residential softener be regenerated on roughly a weekly basis. And regenerating on say a two week basis instead of weekly saves some water but the down side is the condition of the resin can deteriorate, and especially on well water. And it isn't much water being saved to start with.

    Generally and completely too... lol

    I think a house has a known flow rate that will be achieved on a regular basis.

    I'm not sure what you mean by "overstated" but from what else you've said, you must mean it's unimportant, at least in residential applications.

    I disagree and my customers would also because they check the history of their control valve to see if they have exceeded the constant SFR I told them to expect from their softener. I've never heard from any of them that the SFR has been exceeded but... more than a few have said their peak demand flow rate has gotten within a couple gpm of exceeding the figure I gave them.

    We should be addressing the peak demand gpm that will be running through a softener in a house also.

    I say that commercial equipment is basically the same as residential equipment expect it is larger. And it is. So since we can get down to less than 3 ppm of hardness for a steam boiler, we can get down to 0 gpg for residential just as easily. Yet next to no dealer even mentions constant SFR.

    Adding up your figures, I say the total gpm in the example exceeds the constant SFR of a 2.0 cuft softener and it will not give 0 gpg soft water when that happens.

    If you size for the constant SFR of the softener to cover the peak demand gpm flow rate of the house based on how the family actually uses water, you don't have to worry about exceeding the peak flow rate of the softener; or the constant SFR of the softener.

    Maybe that's why most plumbers and dealers never get into it, as if it doesn't matter.

    I disagree because a house with a large tub, maybe 2 person shower and other water using fixtures with a couple kids say 12 years or older, can have a flow rate over the constant SFR of 13 gpm for a 2.0' softener.

    I agree with it being a marketing gimmick but even for someone from California dude, those two statements in BOLD are like a contradiction.
  11. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,185
    Location:
    Maine
    Gary.....OMG YOUR SIGNATURE IS GONE! HOW WILL ANYONE KNOW HOW TO SIZE A SOFTENER ANYMORE !
  12. Gary Slusser

    Gary Slusser That's all folks!

    The LSI was invented to determine IF concrete pipe was being dissolved by the water run through it. It was never meant to be used to determine if a water was aggressive to metal.

    Toward the bottom;
    http://corrosion-doctors.org/Cooling-Water-Towers/corrosivity.htm

    It should only be used to determine scaling potential caused by hardness or the lack of hardness in a water, not to determine corrosion potential of metals.

    And you really do not want any gpg of hardness in any type of water heater, even this SS one.
  13. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,842
    Location:
    Ontario California
    I am with Water Solutions on this one as well. I write warranties for other companies and at their request I intentionally add certain requirements that will make a warranty claim almost impossible.

    Go to an auto parts store and look at their sockets with life time warranties, for a $3 tool, just send it back to the manufacturer with a check for $5 to cover shipping and handling and they will determine if you can have a broken part warranted. :)
  14. cgarai

    cgarai New Member

    Messages:
    21
    Location:
    Sonoma County
    Well thank you all for so much input.

    I looked into salt dosage vs residual hardness leakage and found the link to the Purolite C100E resin. Looks like there is some leakage, but at least not much until you get to really low salt dosages.

    As for the water heater, I read the warranty closer and they say this about water quality:

    "WATER CHEMISTRY REQUIREMENTS – Sodium less than 20mGL.
    Water pH between 6.0 and 8.0.
    Hardness less than 7 grains.
    Chlorine concentration less than 100 ppm."

    I can see right away that I can't use sodium chloride. Also, here it states less than 7 gr/gal hardness, so reblending is not required. My pH however is right at the upper limit.

    As far as my system, I think a 1 cuft system dosed at in the 5-6#/cuft will give adequate performance. Yes there are enough bathrooms and fixtures to exceed SFR of 9gpm. It won't happen often. If the guest bath starts getting used a lot then I can relatively inexpensively upgrade the tank. My concern here is more that I will have the metered regen being over ridden because we don't use enough water in 8 days.

    I suppose an alternative would be to buy a bigger resin tank, but only load it with 1 cuft of resin and program the controller accordingly. If it turns out I need more capacity, all I have to do is add resin and reprogram. Does this make sense or is there a pitfall I haven't considered?

    On another topic, which is likely to reveal a high level of ignorance: Does the rinse water from the regen cycle contain significant chlorine in it? Could it be dumped in a pool as part of the chlorine dose? Obviously it will have a significant amount of calcium in it, but I'm not sure how much in the context of a pool.

    Thanks,

    Chris
  15. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,185
    Location:
    Maine
    Chris, do you already have a softener? If not then there is very little price difference between a 1 cu/ft unit and a 1-1/2 or 2 cu/ft and you will bet better salt efficiency from a larger unit. Sodium won't be a problem either
    Last edited: May 16, 2012
  16. F6Hawk

    F6Hawk New Member

    Messages:
    166
    Location:
    Alaska
    I wouldn't worry about regen frequency, unless you start going over 20-30 days. There are those that will argue frequency, but unless you have really nasty (dirty) water, I wouldn't worry about it too much. My family's use means I will regen about every 5-18 days.

    A 1.5 cu ft resin tank will allow better salt usage, as Tom and others have said; I went with one for that very reason. The price difference is negligible.

    The rinse water will contain about the same chlorine as the incoming water; chlorine will remain in solution unless you remove it chemically, or unless it precipitates out once exposed to air. I'm not a pool expert, but I seem to recal reading somewhere that soft water is not good for a gunite pool...
  17. Gary Slusser

    Gary Slusser That's all folks!

    Your raw water is likely to have more sodium than the 20 mg/l. And IIRC, it's the chloride that corrodes SS, or more than sodium does. IMO it would take either a long time to corrode SS enough to cause a problem in a water heater and I wouldn't worry about it IF I had to have a SS water heater.

    Over running the SFR is not a good idea and you should get the correct sized softener and program it for the best salt efficiency it can give you. That's because you should want to get it done right the first time and gt on with life.

    An metered 8 day regeneration is fairly efficient and if you program at 60 gals/day/person there won't be much capacity left in 8 days to worry about. To change to a larger tank measn you have to change parts in the control valve also. And the plumbing and buy more resin. It's a bad idea.

    The softener drain water needs to go to the septic/sewer system, it is not good for a pool and will mess up the water chemistry due to the hardness possibly but more likely the salt.
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