Water Softner sizing and programming

Discussion in 'Water Softener Forum, problems, installation and r' started by pooleje, Feb 21, 2014.

  1. pooleje

    pooleje New Member

    Messages:
    4
    Location:
    IL
    I've done a fair amount of research and think I've settled on the Fleck 7000SXT valve. My question is about resin tank sizing and programming.

    I've measured our hardness at 16gpg and gotten the following values from the cities water quality report:
    Chlorine 0.5 ppm
    Iron 0.0111 ppb

    We live in a 2.5 bath house with 1 HE Dishwasher and 1 HE Washer. Based on our water bill, the 3 of us (2 adults, 1 child) are currently using a total of 90 gal/day. I'd like to allow room (with programming adjustments) in the sizing for a family of 4.

    I'd also prefer to use potassium chloride, if that makes a difference.

    What size system would you guys recomend?
    Should I get the upgraded resin to handle the chlorine?
    Is the Fleck 7000SXT valve the one I should be looking at and what program setting?
  2. mialynette2003

    mialynette2003 Member

    Messages:
    738
    Location:
    Ocala, Florida
    The compensated hardness in your case would be 16*1.1=17.6 round to 18. This take into count the iron and other hardness ions. Using 90 GPD *18=1620 grains per day * 7 days=11340. So a 1 CF unit will regen about every 12 days.
  3. Gary Slusser

    Gary Slusser That's all folks!

    Chlorinated water has no ferrous iron in it, so the softener is not going to have to remove any.

    Most 'city water' will have a varying amount of hardness, and you should size for the highest level in the water company's system.,If not, at times you will get harder water than your current 16 gpg and in a short time the softener will not remove all the hardness and yet there will be nothing wrong with its operation. Your water company seems to have like 12 different wells and at times one or more will be shut down for maintenance and that usually causes a change in hardness content. You can call them and ask them to tell you the max hardness in their system. They may not like telling you that since it is not on their annual water quality report. And the one you posted is for 2012.

    For a 2.5 bathroom house with 3 people, the average water use is 60 gals/person/day and a 1.0 cuft softener (32K) is going to have a constant SFR (service flow rate) of only 9 gpm.The normal 2.5 bathroom house will need a 1.5 cuft (48K) softener's 12 gpm SFR.

    You can learn all about that by clicking the Click Here link in my signature. You will also learn how to size for the best salt efficiency there, and that to use potassium chloride you need to increase the salt dose lbs from 6% to 27% more than for sodium chloride.
  4. Reach4

    Reach4 Active Member

    Messages:
    2,242
    Location:
    IL
    Expect to pay 3 or 4 times as much per pound of potassium chloride vs sodium chloride.
  5. pooleje

    pooleje New Member

    Messages:
    4
    Location:
    IL
    So, let's talk programming of a 1.5 cuft 7000sxt system.

    Since I want to use potassium, I used a Brine Concentration of 2.87 lb/gal (Saturation point of KCl in H2O at 20deg C) instead of the 3 lb/gal used for NaCl.

    At a dosage of 4 lb/cuft, I would need 6 lb of salt to regenerate 1.5 cuft of resin. At 2.87 lb/gal, that would be 2.09 gal of brine. With a BLFC of 0.25 gal/min, it would take 8.36 min to refill the brine tank. I rounded this up to 9 min for the BF cycle, which should be 2.25 gal of water. Again, using the 2.87 lb/gal, this results in an actual usage of 6.46 lb of KCl.

    I also found an article listing the theoretical max efficiency of KCl at 4702 grains/lb instead of 6000 grains/lb of NaCl. Which I used this to calculate that KCl has 78.3% of the efficiency of NaCl. I used this same % at a dose of 4 lb/cuft to come up with an efficiency of 3135 grains/lb for KCl instead of the 4000 grains/lb for NaCl.

    So with and actual use of 6.46 lb of KCl and an efficiency of 3135 grains/lb, I get 19700 grains of capacity.

    With my usage of 90 gal/day and 16gpg hardness (1440 grains/day), this would result in a regeneration every 13.7 days. Which results in a 1 day safety factor of 8% (1/13.7 rounded up).

    So given all that, I came up with the following programming values:
    DF = GAL
    VT = St2b
    CT = Fd
    C = 19.7
    H = 16
    RS = SF
    SF = 8
    DO = 16
    RT = 12:00AM
    BW = 10
    BD = 60
    BW = 5
    RR = 10
    BF = 9
    FM = t1.2

    Are there any problems with my assumptions or math? I wasn't sure what to use for the 2 backwash times, the brine draw time, or the rapid rinse time. Any changes to those times?
    Last edited: Feb 25, 2014
  6. Reach4

    Reach4 Active Member

    Messages:
    2,242
    Location:
    IL
    Did not go through your numbers. RT seems early to me, but maybe you are an early riser.

    http://www.800mainstreet.com/9/0009-004-solub.html shows that KCl saturation in solution is more sensitive to temperature, but fortunately it is similar to NaCl at room temperatures.
  7. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,836
    Location:
    Ontario California
    KCL is highly sensitive to temperature. I would make a minor changes to your programming.

    1: Brine fill first, VT dFFF, this will greatly reduce the problem of bridging in the salt tank due to water temperature fluctuations between regenerations. If your system is installed in an area that rarely sees temperature fluctuations, this is not critical. If the system is installed outside, or in a minimially temperature controlled basement, or garage, then use this setting.

    I did nothave time to go into the math of it, but it sounds like you know what you are doing.
  8. pooleje

    pooleje New Member

    Messages:
    4
    Location:
    IL
    If I changed to dFFF, I would need to adjust the temperature I'm using in my calculations to the incoming water temperature (about 47F or 8.33C for my area). That would change my Brine Concentration to approx 2.53 lb/gal, the brine required to 2.3728 gal, the BF time to 10 min, and the capacity to 19462. So I would change the C setting to 19.5 and the BF to 10. Would all of the other settings stay the same?

    DF = GAL
    VT = dfff
    CT = Fd
    C = 19.5
    H = 16
    RS = SF
    SF = 8
    DO = 16
    RT = 12:00AM
    BW = 10
    BD = 60
    BW = 5
    RR = 10
    BF = 10
    FM = t1.2

    Is there a place to set the brine soak time, or is that automatic? Does it pre-fill the tank and allow for this soak time before the regen time (RT) or would it finish the regeneration 2hrs later?
  9. Reach4

    Reach4 Active Member

    Messages:
    2,242
    Location:
    IL
    I think it would be the air temperature at the brine tank that would matter, since the incoming water temperature will have adjusted to the basement temperature by the time of the next brine draw. In areas where they put the water softener outside, that temperature would be more variable.

    "brine soak time? In each regen, it draws the brine, and later refills the brine tank with the selected dose of water. That dose of water sits in the brine tank for some number of days before the brine draw of the next regeneration. So would that be a 167 hour brine soak time, if you regen once per week for example?
  10. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,836
    Location:
    Ontario California
    Tha air temperature is critical for wet salt storage, dry salt storage is water temperature based, you are correct. The programming has an adjustable soak time. if you go through the programming, you will notice that it has the brine fill as the first cycle, then the default is 1 hour soak time, then the system goes though a standard regeneration. The valve will also resync and technically you are supposed to change the brine cam to pt# 41498. The cam is a different color and has is nearly identical except that the letters are molded in the correct position. Dont worry about it, just FYI.

    dFFF is also used for variable brining systems. Note: Variable brining should not be used except for systems that can not be sized to regenerate more than every 6 days.
  11. pooleje

    pooleje New Member

    Messages:
    4
    Location:
    IL
    Just a couple more questions.

    Do I need to worry about the .5ppm chlorine when selecting the resin? The dealer I was looking at offers an imported 10% Crosslinked resin or SST-60 as upgrades. The SST-60 looks nice for hardness leakage at low salt dosages but I can't seem to find anything about chlorine resistance.

    Dittohead: Is there an online source you'd recommend for the brine cam? A brief google search didn't turn up anything but the fleck accessory guide.
  12. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,174
    Location:
    Maine
    10% cross linked and SST60 are good resins. Will you notice a difference? Probably not. Do you have some extra money to spend on them? Let's put it this way, using either isn't a bad idea, it's just not really needed.
  13. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,836
    Location:
    Ontario California
    I don't know of an online source for that part. It is identical to your brine cam except the letters are molded in different positions. I will see if I can dig one up today, Iif I can I will send it to you.
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