Water softener abstract
The present invention provides a controller for a water softener
having an ion exchange resin capable of receiving hard water ions
from hard water during a softening step and releasing the hard water
ions during a regeneration step. The controller includes a processor
programmed to cause termination of the softening step and initiate
the regeneration step when both a first and a second condition are
met. The first condition is met when the resin is saturated with
hard water ions, and the second condition is met when current demand
for soft water is at or below a prescribed flow rate.
Water softener claims
What is claimed is:
1. A controller for a water softener, said water softener having
an ion exchange resin capable of receiving hard water ions from
hard water during a softening step and releasing the hard water
ions during a regeneration step, said controller comprising a processor
programmed to cause termination of the softening step and initiate
the regeneration step when both of a first and a second condition
are met, said first condition being met when said resin is saturated
with hard water ions, and said second condition being met when current
demand for water is at or below a predetermined flow rate.
2. The controller of claim 1 further comprising an input from a
hardness sensor used to determine when said first condition is met.
3. The controller of claim 1 further comprising data that is used
by said controller is used to determine when said first condition
4. The controller of claim 3 wherein said data is from a flow meter.
5. The controller of claim 1 wherein said controller comprises
a microprocessor, one or more control valves driven by said microprocessor,
a timer, and a user interface to receive input for said controller.
6. The controller of claim 1 further comprising data from a flow
meter that is used by said controller to determine when said second
condition is met.
7. The controller of claim 1 being configured for having a prescribed
delay between monitoring operations when water demand exceeds said
predetermined flow rate, said controller waits a prescribed delay
time then determines the flow rate again.
8. A water softener comprising: a housing; an inlet to said housing
for receiving inflow of hard water; an outlet from said housing
for dispensing outflow of treated water; an ion exchange resin held
within said housing for receiving hard water ions from the hard
water during a softening step and releasing the hard water ions
during a regeneration step; a processor programmed to cause termination
of a softening step and initiate a regeneration step when both of
a first and a second condition are met, said first condition being
met when said resin is saturated with hard water ions, and said
second condition being met when current demand for soft water is
at or below a predetermined flow rate.
9. The water softener of claim 8 further comprising an electronic
hardness sensor for determining when said first condition is met.
10. The water softener of claim 8 further comprising electronic
memory mounted on or held within said housing for storing information
and calculating if said resin is saturated with hard water ions.
11. The water softener of claim 8 further comprising a flow meter
for determining when said second condition is met.
12. The water softener controller of claim 8 further comprising
one or more control valves, wherein said processor is configured
for causing termination of said softening step and initiation of
said regeneration step by movement of said valves causing one or
more of said valves to change position.
13. The water softener controller of claim 8 wherein said processor
is further programmed with alternate modes of regeneration.
14. The water softener controller of claim 13 wherein said processor
further receives input as to the quality of said hard water and
offers only said alternate modes of regeneration if the water hardness
is sufficiently high or if iron is present in said hard water.
15. A method for controlling a water softener containing an ion
exchange resin capable of receiving hard water ions during a softening
step and releasing the hard water ions during a regeneration step,
said method comprising: initiating said softening step; determining
that a first condition is met when said resin is saturated with
the hard water ions; determining that a second condition is met
when current treated water demand is at or below a predetermined
minimum flow rate; terminating said softening step when both of
said first and second conditions are met; and initiating said regeneration
16. The method of claim 15 further comprising obtaining data from
a hardness sensor for determining if said first condition is met.
17. The method of claim 15 wherein determining when said first
condition is met comprises storing information used to make said
18. The method of claim 15 wherein determining when said first
condition is met comprises obtaining data from a flow meter.
19. The method of claim 15 wherein said terminating step further
comprises rotating a cam.
20. The method of claim 15 wherein determining when said second
condition is met comprises obtaining data from a flow meter.
21. The method of claim 20 wherein when said current water demand
is above said predetermined flow rate said controller waits a delay
time, then redetermines if said current water demand exceeds said
predetermined flow rate.
22. The method of claim 21 wherein said delay time is less than
Water softener description
BACKGROUND OF THE INVENTION
 This invention relates to a controller for a water softener.
More specifically, it relates to a controller for a water softener
that reduces the amount of resin that must be held in reserve prior
to regeneration of the unit.
 Electronic controllers have recently become very inexpensive
and readily available for use in common household items. They are
now regularly used for a number of appliances, including water softeners.
While treating hard water, an ion exchange resin in a water softener
absorbs calcium and magnesium ions from the water and replaces them
with sodium ions. The resin becomes ineffective when the amount
of available sodium is depleted and the resin is saturated with
calcium and magnesium, and must periodically be regenerated. Water
treatment is then suspended while the resin is regenerated in a
multi-step process to flush the calcium and magnesium ions from
the resin and restore the sodium level. The resin is first backwashed,
by reversing the flow of the incoming water, to remove sediment.
Next, the resin bed is contacted with a brine solution, whereby
the resin takes sodium ions from the high concentration solution
and displaces the calcium and magnesium ions into the brine. When
an optimum amount of ion exchange has taken place, the brine solution
and the unwanted hard water ions in it are discharged from the resin
bed. After being rinsed to remove residual brine, the restored resin
bed is then returned to service treating hard water.
 Water softeners use electronic controllers to direct the
timing and the opening and closing of valves during the various
process steps. Some newer, more sophisticated water softeners use
electronics to schedule the next regeneration cycle based on one
or more inputs. The input data includes information from timers,
flow meters, stored historical data on water usage and the like.
 In U.S. Pat. No. 6235200 to Mace, a controller is disclosed
for regeneration of a water conditioner. The apparatus measures
water usage over a predetermined time period, and electronically
stores the water usage data. Information for the same time period
is averaged with similar time slots, such as the same time for previous
days, or the same time period for previous weeks. The controller
thereby determines time slots during which there is no water usage
or when water usage is minimized. When resin saturation reaches
a predetermined level, the controller determines the next regeneration
time based upon historical water usage during given time periods.
Actual current water usage is not used to determine appropriate
 A water softener controller with a microprocessor is described
in U.S. Pat. No. 4490249 to Seal. Water usage is measured by a
flow meter. Based on the flow meter data, the microprocessor determines
the amount of water used since the last regeneration, and also keeps
a running average of daily average soft water consumption. At a
prescribed regeneration time, the microprocessor calculates the
remaining resin capacity, and regeneration is initiated if the resin
capacity is less than that necessary to supply the next full day's
supply of soft water. Regeneration always takes place at the prescribed
time of day.
 The regeneration scheme used in Zabinski, U.S. Pat. No.
5751598 is very similar to that of Seal. Here the regeneration
system is armed using information from a flow meter, a timer or
electrodes that detect the impedance of the solution. Once armed,
regeneration starts at the next predetermined regeneration time.
 Regeneration in a multiple tank treatment system is described
in U.S. Pat. No. 5069779 to Brown. A controller initiates regeneration
of the tank currently in use when the resin in that tank reaches
a predetermined saturation level. The controller also anticipates
saturation of other tanks, and may regenerate the current tank early
if it determines that another tank will become saturated before
regeneration of the current tank is complete. Current water usage
is not a concern with this system since there is a constant supply
of soft water from the tanks that are not regenerating.
 Schreiner, in U.S. Pat. No. 5879559 also teaches the
combination of a mechanical clock and an electronic controller to
operate a drive motor having an output shaft coupled to a valve
system. A switch set by the mechanical clock, and an electronic
ready signal must both be present for regeneration to occur. The
ready signal is generated by a timed signal, such as the day of
the week, or from a demand regeneration scheme. The demand signal
is produced with input from a flow meter when water flow has exceeded
a set value. Immediate regeneration may be initiated by the push
of a button by the user.
 All of these schemes use the electronic controllers to schedule
regeneration some time in the future once some level of saturation
of the resin is obtained. Because the controller schedules the regeneration
to occur in the future, regeneration must be scheduled while there
is sufficient resin to provide soft water during the time between
the time regeneration is scheduled and the time that regeneration
actually begins. If a timer initiates regeneration no more than
once daily, then the reserve resin provided should be no less than
that needed to provide treated water for 24 hours. The resin that
is held in reserve is not used efficiently. Theoretically, it is
possible that this resin will never be used to soften water. Therefore,
the unit has to have resin in reserve that is rarely, if ever, used
to soften water.
 Withholding a portion of the resin in reserve leads to excessive
salt and water usage during regeneration. Brine usage is determined
based on complete saturation of the resin. If up to one third of
the resin bed has not been saturated with calcium ions, the amount
of brine required to regenerate could be reduced by a corresponding
amount. However, because the exact saturation level of the bed is
unknown, the brine usage assumes total resin saturation.
 Another problem with water softeners is finding a predetermined
time to regenerate when there is no current demand for soft water.
Users frequently program the controller to initiate the regeneration
cycle when household members are usually sleeping, for example at
2:00AM. This schedule limits initiation of regeneration to once
a day, requiring that the reserve of useable resin be sufficient
to meet soft water demand for at least 24 hours. Such a rigid schedule
of regeneration also fails to account for unusual circumstances
by the soft water users, such as when a household member desires
to shower after arriving home very late at night.
 None of the prior art provides for monitoring of the current
water usage for the purpose of determining if regeneration should
be delayed due to current soft water demand. Prior control sequences
have used historical determinations as to when water usage is nil
or minimized. However, none have determined that regeneration is
due, then started monitoring current water usage to determine when
there is no present soft water demand.
 It is therefore an object of this invention to provide an
improved controller for a water softener that delays regeneration
if there is a current demand for soft water.
 It is another object of this invention to provide an improved
controller for a water softener that minimizes the amount of resin
that must be kept on reserve.
 It is still another object of this invention to provide
an improved controller for a water softener that provides a fully
automatic setting for the controller, minimizing the amount of input
required from the consumer.
 It is yet another object of this invention to provide an
improved control sequence for a water softener that is more economical
and environmentally friendly due to lower water and salt usage.
SUMMARY OF THE INVENTION
 These and other objects are met or exceeded by the present
invention, which features a controller for a water softener that
does not delay regeneration to a preselected time of day.
 More specifically, the present invention provides a controller
for a water softener. The water softener has an ion exchange resin
capable of receiving hard water ions from hard water during a softening
step and releasing the hard water ions during a regeneration step.
The controller includes a processor programmed to cause termination
of the softening step and initiate the regeneration step when both
a first and a second condition are met. When the resin is saturated
with hard water ions, the first condition is met. The second condition
is met when current demand for water is at or below a predetermined
 The water softener and controller of the present invention
minimizes the inventory of reserve resin by not calling for regeneration
until the bed is substantially saturated. Full use of the resin
reduces the amount of resin that is needed to treat a constant volume
of water. When smaller quantities of resin are required, the housing
can be made smaller since the compartments for storing the resin
and for storing salt can both be reduced in size and still obtain
the same performance. Compact units are more easily designed for
use in small homes or apartments.
 When the resin is used more fully, regeneration needs to
occur less frequently compared to controllers that utilize an average
amount of reserve resin. Resin is held in reserve because regeneration
is primarily controlled by time. At a prescribed time, regeneration
begins regardless of the saturation of the remaining resin. If 20%
of the resin is consistently not used in a unit that regenerates
daily, an extra regeneration is required every 4 days. Sufficient
salt and water are used to regenerate the entire bed, even though
the reserve resin does not need regeneration. Extra water and salt
usage makes operation of the softener more expensive for the user
and puts a strain on the environment.
 The controller of the instant invention also makes it easier
for a novice or disinterested user to efficiently use his softener.
One with no experience in the operation of a water softener may
have no idea when or how to schedule regeneration of the unit. With
the controller of this invention, the user need only answer a few
questions programmed into the controller to be assured that the
unit will regenerate as needed but still minimize use of water and
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a schematic diagram of a water softener with the
controller of the present invention;
 FIG. 2 is a water softener of the present invention with
portions of the cabinet and resin tank cut away; and
 FIG. 3 is a flow diagram of the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
 Referring to FIGS. 1 and 2 a water softener, generally
designated 10 has an ion exchange resin capable of receiving hard
water ions from hard water during a softening step and releasing
the hard water ions during a regeneration step. The softener has
controller, generally designated 12 including a processor programmed
to cause termination of the softening step and initiate the regeneration
step when both of a first and a second condition are met. The first
condition is met when resin 14 is saturated with hard water ions
and the second condition is met when current demand for soft water
is at or below a predetermined flow rate.
 The softener 10 includes a housing or tank 16 that holds
a quantity of the ion exchange resin 14. When the softener 10 is
designed for home use, the housing 16 is generally a single unit,
however, a suitable softener optionally has two or more pieces that
constitute the housing. In the preferred embodiment, a resin tank
20 is surrounded by a brine tank or salt chamber 22. Other softeners
are known having separated resin tanks and brine tanks. For the
purposes of this invention, all units are considered to be included
in the housing 16.
 The water softener 10 also has an amount of a softening
agent 24 in the salt chamber 22. Sodium salts, such as sodium chloride
in pellets, provided in a solid block or in a granular form, are
the most common softening agents 24 but any solid softening agent,
such as a potassium salt, is contemplated for use with this invention.
High purity salts are recommended to lengthen the time between salt
additions and to reduce the amount of impurities that accumulate
in the bottom of the water softener 10 but salt purity does not
directly effect the operation of the controller 12 or softener 10
 Referring to FIG. 1 during softening, the controller 12
operates valves to allow fresh, hard water from a supply 26 to flow
into the resin tank 20 through an inlet 28 and treated or soft
water exits through an outlet 30. Between the inlet 28 and the outlet
30 the hard water contacts the sodium-rich ion-exchange resin 14
where hard water ions, including calcium and magnesium ions, are
received by the resin, and sodium ions are released into the soft
water. Softened water is discharged from the softener 10 through
the outlet 30.
 When the resin 14 is saturated with hard water ions and
the sodium or potassium ions are depleted, the resin is regenerated.
During regeneration, a brine solution 32 is withdrawn from the salt
chamber 22 through a brine valve 33 and enters the resin tank 20.
A brine well 34 seen best in FIG. 2 keeps the particles of the
softening agent 24 from clogging the brine valve 33 while allowing
the brine solution 32 to flow freely to the valve. Hard water ions
are released from the resin 14 into the brine solution 32 as sodium
ions from the brine are absorbed by the resin. Spent brine 32 is
removed from the resin tank 20 to a discharge pipe 36 and ultimately
to a drain 40 (FIG. 1).
 At the end of the regeneration cycle, water is added to
the salt chamber 22 so that the softening agent 24 dissolves, making
the saturated brine solution 32 to be used during the subsequent
regeneration. The brine solution 32 is kept separate from the water
supply 26 and resin 14 while softening is taking place so that the
brine 32 does not contaminate the fresh water supplies, and because
ion exchange between the resin 14 and the hard water would not occur
efficiently in the presence of brine. Only during the regeneration
cycle is the brine solution 32 brought into contact with the ion
exchange resin 14.
 Where it is necessary to have an uninterrupted soft water
supply, multiple resin tanks 20 may be used so that one unit is
softening while one or more others are regenerating. For home use,
the entire water softener is often contained in a one-piece housing
16 or cabinet as shown in FIG. 2. Some water softener designs utilize
the cabinet 16 as the salt chamber 22 allowing the softening agent
24 to be placed into the cabinet and occupy space around and between
other elements of the softener 10. The resin tank 20 separates the
ion exchange resin from the softening agent 24. Preferably, the
resin tank 20 is a smaller tank that is housed inside the cabinet
16 of the water softener 10. However, the salt chamber 22 and the
resin tank 20 may both be portions of the cabinet 16 that are separated
from each other by dividers or partitions inside the cabinet, or,
the salt chamber 22 and the resin tank 20 may be entirely separate
tanks. Any arrangement may be used for the salt chamber 22 and resin
tank 20 that keeps the water being softened from contact with the
brine solution 32.
 The controller 12 initiates and controls the regeneration
cycle. For the purposes of this invention, the controller 12 includes
one or more control valves 46 a microprocessor or micro-computer
control unit 48 a timer 50 and a user interface 52. Some duties
of the unit controller 12 include timing of the softening and regeneration
cycles, and the opening and closing of the valves 46 as appropriate.
The controller 12 may perform other tasks as well. Most modern water
softening systems include a microprocessor 48 in the unit controller
10. It should be appreciated that the microprocessor 48 may have
functions not specifically described in this application that are
not a part of this invention, even when carried out by the same
or similar equipment. Although the controller 12 of the present
invention, as described, is most advantageously designed to be used
with such modern water treatment systems, the controller 12 and
process of this invention may also be used with less complex systems
or retrofit into older water softener units 10. Use of a second
microprocessor 48 dedicated to determining when to initiate regeneration
is also contemplated.
 Process steps are directed by the controller 12 by movement
of the one or more control valves 46. In the preferred embodiment,
the single valve 46 positions determine whether hard water or brine
flows into the resin tank 20. Any electronically actuated valve
46 is suitable for the valve 46 including solenoid valves, or valves
controlled by an electronically controlled rotary cam.
 During the softening step, hard water from the supply 26
flows into the resin tank 20 then to the outlet 30 to supply soft
water to the building. When the resin 14 is being regenerated, the
control valve 46 is repositioned to drain brine 32 from the brine
tank 22 and send it to the resin tank 20. After contacting the resin
14 the spent brine is discharged to the drain 40. The control valve
46 is also used to send water from the supply 26 to the brine tank
22 to backflush the resin 14 and perform other process steps as
required by the softener 10.
 The electronic controller 12 is driven by a set of instructions,
preferably in the form of a software program. Preferably, software
is preloaded into memory of the microprocessor 48 at the point of
manufacture. Alternately, the instruction set could be loaded onto
firmware, such as read-only memory for installation into the microprocessor
48. Any method of electronically storing the instructions is suitable
as long as the instructions are readily available to the controller
 Initiation of regeneration by the controller 12 or method
of the present invention is intended to be one option from among
many regeneration modes. Modern electronic controllers 12 optionally
offer a variety of additional ways to determine when regeneration
is appropriate, depending upon the needs or preferences of the user.
This scheme is particularly suitable with a compact softener 10
where space considerations limit the amount of resin 14 available
to be held in reserve. However, under certain circumstances, as
where the hardness of the water is very high or where certain minerals,
such as iron are present, other methods of regeneration are preferred.
Based on input as to the quality of the hard water, the controller
12 optionally selects, or recommends for the user to select, alternate
regeneration modes that may or may not include the efficiency mode
of the present invention. Alternate regeneration modes are based
on the time of day, the saturation of the resin 14 or any other
suitable conditions. Even though the processor 48 is programmed
to use the efficiency mode, it need not offer this particular regeneration
mode if the hard water quality does not warrant its use.
 The high efficiency controller 12 of the present invention
initiates regeneration when two independent conditions have been
met. A first condition indicates that the resin 14 is saturated
with hard water ions to a predetermined level. The second condition
specifies that current demand for treated water is at or below a
minimum flow rate. When both of these conditions have been met,
the controller 12 immediately initiates regeneration without regard
for the time of day or other criteria.
 The resin 14 is saturated when the hard water ions have
replaced a high percentage of the available soft water ions at the
exchange sites. As the hard water contacts the resin 14 ion exchange
usually occurs at the first opportunity the hard water ions have
to exchange with soft water ions. During the softening step, a front
moves through the resin bed 14 from the bed inlet to the outlet,
whereby ion exchange takes place at the front. The resin 14 located
toward the inlet 28 from the front is saturated, while the resin
located toward the outlet 30 still holds soft water ions. When the
front nears the bed outlet, the bed is saturated and regeneration
is required. The physical location of the bed inlet and outlet are
determined by whether the softener 10 is regenerated in an upflow
or downflow fashion.
 Some small reserve of resin is used to provide soft water
while the controller 12 determines if the second condition is met.
However, the reserve in the present system is very small compared
to the prior art. The bed 14 is considered saturated when 90% of
the resin holds hard water ions. Preferably, the resin 14 is at
least 95% saturated before regeneration is triggered. Even more
preferably, the bed 14 is saturated when the bed has the capacity
to soften the average water usage for less than one hour. For the
purposes of this invention, estimated saturation values of the resin
14 are sufficient.
 Information as to the saturation level of the resin 14 is
obtainable from a variety of sources. One preferred signal source
includes one or more sensors 56 that directly monitor the condition
of the resin bed 16. One or more of the hardness sensors 56 such
as the Culligan AQUASENSOR.RTM., (Culligan International, Northbrook,
Ill.) could be placed in appropriate locations within the resin
bed 14 to send a signal when the bed is saturated with hard water
ions to a certain level. The resin 14 is considered to be saturated
when the resin has a supply of sodium ions so low that it will be
unable to treat a minimum amount of hard water, for example, the
amount used by the household in about an hour or less. This minimum
resin reserve gives the controller 12 only this short time (one
hour or less) to wait until current water demand has been reduced
or eliminated as discussed in greater detail below. Preferably,
the resin 14 is considered to be saturated when less than 100 gallons
of water is treatable or when one hour of soft water remains. After
this time period has expired, the water being piped through the
house will be hard water, regardless of whether or not regeneration
 Another preferred source of information is a water meter
60 for estimating the saturation of the resin 14 instead of or
in addition to a direct reading from the sensors 56. Demand for
treated water is preferably monitored by the water flow meter 60.
Preferably the meter 60 is a flow meter that measures the volume
of fluid flowing through it. The meter 60 is suitably mounted either
within the housing 16 or outside the housing of the softener 10.
Electronic meters are preferred, however, any metering device 60
is suitable as long as it sends electrical signals to the controller
 Electronic memory 61 in the microprocessor 48 is used to
store information needed by the microprocessor to calculate the
appropriate saturation level of the resin bed 14. Data as to the
volume V of water that has been treated since the last regeneration,
is preferably calculated and stored by the microprocessor 48. The
amount and type of resin 14 used in the softener 10 is used to calculate
the approximate capacity of the resin, C, in grains of hardness.
The average hardness of the incoming hard water measured in grains
per gallon, H, is also required. Estimated percent bed saturation,
S, is obtained by calculating the ratio of the number of hard water
ions accumulated since the prior regeneration to the total number
of ion-exchange sites available:
 Referring to FIG. 2 some of the above information is obtained
by the controller by direct input of the information into the microprocessor
48. Any method of inputting data to a microprocessor 48 is suitable.
Preferably, the controller includes a display 62 capable of asking
for information and the user interface 52 such as keys or buttons,
useful for inputting data. The capacity of the type and quantity
of the resin, C, is optionally preset when the softener 10 is made.
However, the average water hardness, H, will depend on the water
conditions where the softener 10 is used, and thus is input by the
user at the interface 64. As part of the initial set-up of the softener
10 the controller 12 should be programmed with this information,
preferably by asking one or more questions on the display 62 then
storing the response entered by the user with the interface 64.
Alternatively, the controller 12 could receive data through a personal
computer, input through voice recognition software, or any other
commonly known method.
 Questions asked of the user are also preferably used to
provide information to the controller 12 as to the quality of the
hard water used to determine the suitability of this method of scheduling
regeneration. When the water is particularly hard, or where certain
metals, such as iron, are present, the software optionally selects,
or allows the user to select, a scheduling mode other than the efficiency
mode of the present invention.
 After the first condition is met, the controller begins
to monitor the water flow meter 60 for water demand. The second
condition is also required to be met before to initiation of the
regeneration step, the "low flow" condition. Because the
water bypasses the treatment step during regeneration, it is generally
undesirable to begin the regeneration process while soft water is
in use. Although water is available during regeneration through
the bypass valve (not shown), flow is restricted compared to flow
during the softening cycle. Thus, regeneration is delayed while
the water demand is high, even beyond complete saturation of the
resin 14 to maintain water flow rates. Thus, even when the resin
14 is essentially saturated, regeneration is delayed only very briefly
until water demand is terminated or until the water demand is at
or below a maximum level.
 Referring now to FIG. 3 hard water contacts the ion exchange
resin 14 during a softening step 70. While softening takes place,
the controller periodically determines if the resin is saturated
72 by calculating S using current values of H, V and C, by checking
input from a hardness sensor 56 or by any other suitable means.
If the resin is not saturated, the controller 10 makes no change
in the control valves 46 allowing the softener 12 to continue to
treat hard water.
 If the controller 10 determines that the resin is saturated
72 it then begins to monitor the current water usage 74 preferably,
by reading the flow meter 60. If water demand exceeds D in step
76 the controller 12 waits a prescribed time, T, before again checking
to determine if the water demand is less than D. Water demand, D,
and the time, T, are determined by a variety of techniques. Numerical
values, representing D and T are optionally entered at the user
interface 52 and stored in the microprocessor 48 of the controller
12 making the value easily changeable. Most preferably, D is equal
to 0 and T is 15 minutes. Values of D larger than zero are useful
when the user is willing to allow regeneration to begin when small
quantities of water are being used, such as getting a drink of water,
rather than large quantities, as when taking a shower. Values of
D that exceed the flow rate of water through the bypass valve (not
shown) are not suitable. The maximum water demand, D, is also suitably
calculated by the microprocessor 48 based upon any useful criteria,
such as time of day, historical water usage, day of the week and
the like. Values of T that exceed the average time to saturate the
small reserve of resin 14 are unsuitable. Preferably, the delay
time T is less than 30 minutes, and more preferably, less than 20
minutes. The most preferred value for T is about 15 minutes.
 If current water demand exceeds D, the controller begins
again monitoring the demand over a new time period 78. Only when
water usage is less than D does the controller 10 initiate the regeneration
step 80 immediately. No additional resin 14 is held in reserve to
provide water treatment until regeneration commences at a predetermined
time of day. Regeneration proceeds using any suitable process known
to release the hard water ions from the resin 14 and restore sodium
or potassium ions. Termination of the softening step 70 and initiation
of the regeneration step 80 preferably occurs by manipulation of
the control valves 46 channeling flow of water and brine to appropriate
places at appropriate times.
 Following regeneration, the information stored by the microprocessor
48 is optionally updated. The amount of water measured by the flow
meter 60 since the previous regeneration, W, is reset to zero, and
any historical data that may be useful to the controller 12 such
as water usage or regeneration times should be stored and reset.
Data from the flow meter 60 need not be stored or reset when the
sensors 56 are used.
 Regeneration is complete and the softening step is commenced
when the hard water ions, Ca++ and Mg++ are removed from the resin
14 and eliminated from the softener 10 in the waste brine 36. The
sodium and potassium ions from the brine replace calcium and magnesium
ions, producing soft water. When the softening step begins, the
controller 12 begins tracking the volume of softened water using
the timer 50 provided for the purpose of estimating the next resin
 While a particular embodiment of the water softener controller
has been shown and described, it will be appreciated by those skilled
in the art that changes and modifications may be made thereto without
departing from the invention in its broader aspects and as set forth
in the following claims.