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Thread: Salt Dosage and Fleck 6700XTR, or any head for that matter

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  1. #1
    DIY Junior Member cgarai's Avatar
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    Default Salt Dosage and Fleck 6700XTR, or any head for that matter

    Hi,

    Trying to figure out the salt dosage settings on this Fleck head though I believe the following would apply to most electronic heads. It is a downflow brining head. Although it has a salt dosage in the menu it is only available for the upflow configuration. I can set the head to be upflow, but the valve body isn't set up for it and I don't know what happens if I set it to upflow. Does it open the valves to do down flow, but provide the other setting features offered in upflow? I haven't tried experimenting yet.

    PLEASE CHECK THE FOLLOWING CALCS TO SEE IF I HAVE THE CONCEPTS. THANKYOU!

    So I assume that I need to control salt dosage based on the following:

    1. Resin Volume
    2. BFLC flow rate
    3 Salt dosage

    From these numbers I can calculate the required brine and rinse time.

    So for my system:

    Resin Vol = 1.5 cuft (Nominal 48K grains capacity)
    BFLC = .125 gpm
    Salt dosage = 6#/cuft

    The other required bit of info is the amount of salt in the brine. Brine Conc = 3#/gal is assumed. I have seen it listed as low as 2.6#/gal

    The calcs run like this (in my head):

    Salt required = Resin Vol * Dosage = 1.5 cuft * 6#/cuft = 9 # of salt

    Brine (gal) = Salt Req / Brine Conc = 9#/(3#/gal) = 3 gal of brine.

    Brine&Rinse time = Brine/BFLC flowrate = 3 gal/(.125gal/min) = 24 min

    Does that seem correct? I can't see another way the amount of salt could be controlled.

    The remaining question is what to enter for system capacity on this Metered valve. The nominal capacity is 48kgr, but that is at a salt dosage of 15#/cuft. My understanding that

    Salt Dosage Capacity
    6#/cuft 20Kgr/cuft
    15#/cuft 32Kgr/cuft

    so my system capacity is

    48Kgr * (20kgr/cuft)/(32kgr/cuft) = 32Kgr.

    My assumption is that 32kgr is the proper number to enter for capacity in the setup for this head.


    My understanding is that for a given head/valve/resin tank combo the brine time is what controls the salt dosage. For a bigger BFLC flow rate, less time is needed, for a larger resin volume more time is needed.

    My other understanding is that the system capacity setting on any head must be set to a compensated level based upon salt dosage. The exception to this would be a head that allows you to set the salt dosage directly. In that case the head does the above math and sets the brine time appropriately.

    The people that sold me my unit are telling me that setting for lower salt dosages is a flawed concept and their setup instructions do not adjust brine time for system capacity. I just can't believe that is true from everything I have read.

    Thanks,

    Chris

  2. #2
    DIY Senior Member F6Hawk's Avatar
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    Default

    For the most part, correct calculations. But there is the theoretical max of a softener (48K in your case) vs. the practical capacity (45K). The normal dosing numbers are:

    1 cu ft 1.5 cu ft
    4# - 16K 24K
    6# 20K 30K
    8# 24K 36K
    10# 27K 40.5K
    15# 30K 45K

    Also, 48 * 20 / 32 = 30K, not 32K

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    DIY Junior Member cgarai's Avatar
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    Thanks F6Hawk for checking my arithmetic! And for the reply. Maybe it is me, but it seems that I haven't been able to find that info in one clear place. Is there a sticky somewhere that explains this? If not, there should be.

    Thanks again,

    Chris

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    That's all folks! Gary Slusser's Avatar
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    You need to come up with how many gallons between regenerations you need/want. That gives you the length of time (days) between regenerations. And it and a calculation of your peak demand flow rate should have been done before you buy a softener.

    Then you take the K of capacity you need for the regeneration schedule (gallons over how many days) and find the salt efficiency you want and then the lbs of salt (3lbs/gal of refill) is required to make that happen. You would add to that any reserve capacity you need IF your control valve doesn't have variable reserve, which yours does.
    Gary Slusser Retired (= out of business)
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    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

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    DIY Junior Member cgarai's Avatar
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    Thanks, I did all that before hand. Now I'm just trying to get the system setup. In my case the SFR set the size of the system quite high compared to my average water use and hardness, which is quite low compared with the nominal 75 g/day/person normally assumed. Thus the time between regens will be at the upper end (20days plus if our water usage doesn't change) of what I have read is acceptable.

    Chris

    Quote Originally Posted by Gary Slusser View Post
    You need to come up with how many gallons between regenerations you need/want. That gives you the length of time (days) between regenerations. And it and a calculation of your peak demand flow rate should have been done before you buy a softener.

    Then you take the K of capacity you need for the regeneration schedule (gallons over how many days) and find the salt efficiency you want and then the lbs of salt (3lbs/gal of refill) is required to make that happen. You would add to that any reserve capacity you need IF your control valve doesn't have variable reserve, which yours does.
    Last edited by cgarai; 06-29-2012 at 11:54 PM. Reason: add some thoughts

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    DIY Junior Member FleckLander's Avatar
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    "From these numbers I can calculate the required brine and rinse time."

    Just so everyone is on the same page, it's my understanding that the standard softener cycles are backwash, followed by brine draw/slow rinse, followed by rapid rinse, followed by brine fill. (Assuming no double backwash and postfill brine fill)

    The cycle that you want to set to 24 min to get your desired 9 lb total salt dose is the BRINE FILL, not the "brine and rinse time". Your seller is probably taking your referring to "brine and rinse time" as the brine draw/slow rinse cycle which would be more like 60 minutes for a generic setting.

  7. #7
    That's all folks! Gary Slusser's Avatar
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    Quote Originally Posted by FleckLander View Post
    "From these numbers I can calculate the required brine and rinse time."

    Just so everyone is on the same page, it's my understanding that the standard softener cycles are backwash, followed by brine draw/slow rinse, followed by rapid rinse, followed by brine fill. (Assuming no double backwash and postfill brine fill)
    That postfill should be PRErefill.

    Quote Originally Posted by FleckLander View Post
    The cycle that you want to set to 24 min to get your desired 9 lb total salt dose is the BRINE FILL, not the "brine and rinse time". Your seller is probably taking your referring to "brine and rinse time" as the brine draw/slow rinse cycle which would be more like 60 minutes for a generic setting.
    Good catch.

    The 60 minutes slow rinse/ brine draw is a default setting from the factory, as all the settings are. Depending what and how much of it is in the water, like iron, I usually shorten that cycle time along with the backwash and final rinse cycles.
    Gary Slusser Retired (= out of business)
    Click Here to learn how to correctly size or program a water softener.
    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

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    DIY Junior Member cgarai's Avatar
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    Quote Originally Posted by FleckLander View Post
    "From these numbers I can calculate the required brine and rinse time."

    The cycle that you want to set to 24 min to get your desired 9 lb total salt dose is the BRINE FILL, not the "brine and rinse time". Your seller is probably taking your referring to "brine and rinse time" as the brine draw/slow rinse cycle which would be more like 60 minutes for a generic setting.
    Now that is not my understanding at all. The Brine Fill cycle refills the brine tank. The Brine/Slow Rinse (I was a little sloppy with my terminology before) is where brine is being fed into the resin tank along with water. At least that is what the service manual shows.

    I hadn't really considered the Brine Fill cycle. This will depend on the size of the brine tank and the flow rate into the tank. There is an float type shut off valve, but it probably best to adjust the time so that one isn't relying the float valve.

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    DIY Senior Member F6Hawk's Avatar
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    As you noted above, you need 3 gallons of water to put 9 lbs of salt into solution; the way you get 3 gallons is to divide 3 by your .125 to get 24 minutes of BRINE FILL time. This happens at the end of the regen cycle, leaving water for the next cycle of Brine/slow rinse. The industry standard seems to be 60 minutes on the draw, but you will have sucked out all the brine in about the first 20 minutes or so.

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    That's all folks! Gary Slusser's Avatar
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    Quote Originally Posted by cgarai View Post
    Now that is not my understanding at all. The Brine Fill cycle refills the brine tank. The Brine/Slow Rinse (I was a little sloppy with my terminology before) is where brine is being fed into the resin tank along with water. At least that is what the service manual shows.

    I hadn't really considered the Brine Fill cycle. This will depend on the size of the brine tank and the flow rate into the tank. There is an float type shut off valve, but it probably best to adjust the time so that one isn't relying the float valve.
    The size of the salt tank has nothing to do with it.

    You can't get brine until the salt is dissolved, and that happens in the brine tank after the brine refill water has been added to the brine tank. The brine refill is added by the minute at your DLFC rating (.125 gpm). And that float, it is not used to stop the brine refill water flow, it is a safety float operated shut off valve to prevent salt brine from overflowing the tank onto the floor if something goes wrong and the brine water rises too high, which can happen fairly frequently.

    Your control valve allows for PRE refill, meaning the refill water is added before a regeneration starts, as the first cycle position, then there is a pause and after that the control valve starts the backwash, slow rinse/BRINE DRAW meaning suck the brine water out of the brine tank into the resin tank. You can't have brine draw without the slow rinse water flowing.

    It takes 2 hours for the brine refill water to totally dissolve all the salt needed for the regeneration salt dose. Post refill is done as the last cycle position of a regeneration.

    BTW, water companies say the average gals/person/day is 60, and its been that way for a very long time but especially since shower heads, dish/clothes washing machines, toilets and sink fixtures have had to meet water conservation mandated maximum gpm etc. ratings. I've used 60 gals since the late 1980s and I have no idea why Fleck still uses 75 unless it's to pad the reserve capacity of the softener for uninformed dealers.

    Lastly... the 60 minutes of slow rinse/brine draw is a factory default setting, and many dealers would rather not be bothered in changing it or informing their customers of why it should be changed, or to what it should be changed to based on their water quality and the size of the softener. The rest of the original programing is factory default also and each control valve manufacturer has their own default settings. Sad to say that most dealers, plumbers etc. do not know what to set them to so they say the settings are just fine.
    Gary Slusser Retired (= out of business)
    Click Here to learn how to correctly size or program a water softener.
    CAUTION, as of Nov 12 2013 all YouTube videos showing how to rebuild a Clack valve have an error in them that can cause damage.

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