Apparatus for controlling water level

Apparatus for monitoring and controlling the level of fluid in a reservoir. The apparatus utilizes a fluid sensing probe to monitor the level of fluid in a reservoir and can generally be installed in an existing fluid reservoir without requiring structural modification of the reservoir. The apparatus, in determining the level of fluid in a reservoir, compensates for swells and other surface undulations which mask the true fluid level in the reservoir.

This invention pertains to apparatus for monitoring and controlling the 
level of fluid in a reservoir. 
More particularly, the invention pertains to water level control apparatus 
which can be readily installed in various types of fluid reservoirs 
without requiring that portions of the reservoirs be reconstructed or 
otherwise structurally modified. 
In a further respect, the invention pertains to apparatus for controlling 
the level of water in a reservoir, the apparatus not requiring the 
utilization of moving parts which contact water in the reservoir and are 
therefore susceptible to being damaged by corrosion or by the accumulation 
of calcium and other mineral deposits on the moving parts. 
In another respect, the invention pertains to water level control apparatus 
which, in determining when water should be added to a reservoir of water, 
takes into account and compensates for swells and other surface 
undulations which mask the true water level in the reservoir. 
In yet a further respect, the invention pertains to water level control 
apparatus which utilizes an electrically conductive probe to monitor and 
control the water level in a reservoir. 
Systems for monitoring and controlling the water level in a swimming pool 
or other fluid reservoir are well known in the art. However, such systems 
are not readily installed in an existing swimming pool because they 
require a significant amount of structural modification of the cool deck 
or walls of the swimming pool. In addition to being difficult to install, 
conventional water leveling systems are costly to maintain and often 
include moving parts which are, because they must continually contact 
swimming pool water, susceptible to damage caused by fatigue corrosion and 
the accumulation of calcium and other mineral deposits. One conventional 
water level control system is the POWERSTREAM automatic refill system, 
Model ARS-350 marketed by Flow-Rite Controls, Ltd. of 700 West 193rd 
Street, Glenwood, Ill. 60425. The POWERSTREAM system utilizes a pressure 
sensor positioned in the side wall of a swimming pool. The sensor detects 
the force generated against the sensor by the volume of water in the pool 
above the sensor. When the water level in a swimming pool decreases to a 
predetermined level, the sensor automatically opens a valve to add water 
to the pool. Installation of the POWERSTREAM system is costly because the 
pool must be drained, the earth adjacent the pool wall excavated, and the 
wall bored in order to install the pressure sensor. Maintenancing or 
replacing the sensor is equally expensive. Other conventional water 
leveling systems utilize floats which are susceptible to corrosion and to 
the accumulation of calcium and mineral deposits. Installation of float 
systems in existing swimming pools also normally requires additional 
concrete construction and the destruction and replacement of portions of 
existing pool walls and cool deck. Water level control systems utilizing 
electrical sensors are presently not favored for swimming pools because of 
safety considerations. 
Accordingly, it would be highly desirable to provide an improved water 
level control system which could be quickly and inexpensively maintenanced 
and which could be readily installed on existing swimming pools by 
individuals of limited mechanical skill utilizing only simple conventional 
hand tools. 
Therefore, it is a principal object of the invention to provide an improved 
system for controlling the level of fluid in a reservoir. 
A further object of the invention is to provide an improved water level 
control system which can be quickly installed in existing swimming pools 
with conventional hand tools and without requiring structural modification 
of the walls or deck of the pools. 
Another object of the instant invention is to provide an improved water 
level control system which is, after being installed in a fluid reservoir, 
readily maintenanced at minimal cost.

Briefly, in accordance with my invention, I provide improved apparatus for 
adding fluid to a reservoir, the reservoir normally being filled with 
water to a desired level therein. The apparatus includes a probe having a 
water sensing tip generally maintained in fixed position above the 
reservoir such that the sensing tip contacts the water when the reservoir 
is filled to the desired level and the sensing tip is spaced above the 
water when the reservoir is filled to a level lower than the desired level 
of water in the reservior; a control unit in communication with the probe 
to monitor when the sensing tip is contacting water in the reservoir and 
when the sensing tip is spaced away from and not contacting water in the 
reservoir; a conduit through which water flows into the reservoir; and, a 
valve operatively associated with the control unit and positioned in the 
conduit. The valve has at least two operative positions, a normally closed 
position in which water is prevented from passing through the conduit into 
the reservoir, and an open position in which water flows through the 
conduit into the reservoir. The control unit moves the valve to the open 
position to permit water to flow through said conduit into the reservoir 
when the sensing tip of the probe is spaced away from and not contacting 
water in the reservior. 
In another embodiment of my invention, I provide an improved method for 
adding fluid to a reservior. The reservoir is normally filled with water 
to a desired level therein and includes a deck adjacent at least a portion 
of the reservoir. The deck includes at least a pair of adjacent sections 
of material spaced apart from one another along a joint line. The improved 
method includes the steps of installing an electrically conductive probe, 
a control unit, and a conduit. The electrically conductive probe has a 
water sensing tip in fixed position above the water in the reservoir such 
that the sensing tip contacts the water when the reservoir is filled to 
the desired level, and the sensing tip is spaced above the water when the 
reservoir is filled to a level below the desired level. The control unit 
is positioned generally near the reservior in electrical communication 
with the probe to monitor when the sensing tip is contacting water in the 
reservoir and when the sensing tip is spaced away from and not contacting 
water in the reservior. The electrical communication between the probe and 
the control unit is provided by at least one electrically conductive wire 
extending from the probe along the joint line between the pair of sections 
of material to the control unit. The conduit directs water into the 
reservoir and includes a valve having at least two operative positions, a 
normally closed position in which water is prevented from passing through 
the conduit into the reservoir and an open position in which water flows 
through the conduit into the reservior. After the probe, control unit and 
conduit are installed, the remaining step in the improved method of the 
invention is to open the valve when the control unit determines the water 
sensing tip is spaced away from and above the water in the reservior. 
Turning now to the drawings, which depict the presently preferred 
embodiments of the invention for the purpose of illustrating the practice 
thereof and not by way of limitation of the scope of the invention, and in 
which like reference characters refer to corresponding elements throughout 
the several views, FIG. 1 illustrates a water level control system 
constructed in accordance with the principles of the invention for a 
swimming pool generally indicated by reference character 11 and including 
wall 12 enclosing electrically grounded water 13 having a desired level 
within wall 12 indicated by horizontal line L. Cylindrical L-shaped 
standpipe 14 in wall 12 includes removable cap 15. Probe unit 16 is 
detachably fixedly affixed to the bottom of cap 15. Wire 17 from probe 
unit 16 extends from standpipe 14 through expansion joint 18 in deck 19 to 
control unit 20. Wire 17 can, instead of being coursed through expansion 
joint 18, be directed from standpipe 14 through a hollow piece of PVC or 
other conduit buried in or below deck 19. While expansion joint 18 is 
illustrated in FIG. 1 as being a generally horizontally oriented layer 
between deck 19 and deck support foundation 21, it is understood that in 
the cool deck surrounding most swimming pools each expansion joint 
comprises a vertical panel shaped space between adjacent slabs of cool 
deck or concrete. Wire 17 would therefore, in most existing pools, extend 
through a vertical panel shaped expansion joint space between a pair of 
adjacent concrete slabs to the edge of the cool deck. From the edge of the 
cool deck wire 17 would preferably extend through a hollow buried conduit 
to control unit 20. 
As shown in FIGS. 2 and 5, probe unit 16 includes hollow cylindrical 
housing 57 having aperture 58-63 formed therethrough. Caps 24, 25 snap 
onto the top and bottom of housing 57, respectively. Electrically 
conductive externally threaded brass probe 26 is secured to cap 24 by nuts 
27, 28. Metal contact 29 crimped onto wire 30 contacts probe 26 and is 
compressed between the top of cap 24 and nut 28. In FIG. 1, probe unit 16 
is positioned such that tip 27 of probe 26 is at point 30 on line L, i.e., 
tip 27 is at the desired water level of reservoir 11. Line 32 on the 
exterior of housing 57 indicates the position of tip 27 of probe 26 in 
housing 57 and, consequently, indicates the preferred level L of water 13 
on probe housing 57 when housing 57 is in standpipe 14. 
Control unit 20 includes electrical contacts 31 which receive power from a 
110 or 220 VAC power source. Lines 34, 35 electrically connect control 
unit 20 to normally closed valve 33 in water supply conduit 36. Control 
unit 20 must, along with water 13, be grounded 42 in order for probe unit 
16 to function correctly. During operation of the apparatus of FIG. 1, 
valve 33 is automatically opened and closed by control unit 20. Time dial 
38 can be set to two, five, ten or fifteen minutes and indicates the 
length of time control unit 20 will open valve 33 when probe unit 16 
indicates to unit 20 via wire 17 that the level of water 13 is below the 
desired level indicated by line L. LED 40 turns on when the level of water 
13 is below the desired L and below tip 27 of probe 26. LED 41 lights when 
control unit 20 opens valve 33 to permit water to flow through conduit 36 
into reservoir 11 as indicated by arrows W. Valve 33 is not opened by 
control unit 20 until LED 40 has been lit for a pre-selected period of 
time. It is presently preferred that control unit 20 not open valve 33 
until probe tip 27 has not contacted water 13 for a period of time 
equivalent to one-half of the time setting of knob 38. For example, in 
FIG. 1 knob 38 is set at ten minutes. Consequently, control unit 20 opens 
valve 33 after probe tip 27 has not contacted water 13 for a continuous 
period of five minutes. As soon as tip 27 of probe 26 has not contacted 
water 13 for five minutes, the microprocessor in control unit 20 opens 
valve 33 for ten minutes and then closes valve 33. 
A conventional swimming pool 11 skimmer 50 with filter basket 51 is 
illustrated in FIG. 3. Conduit 52 carries water 13 to the pool pump and 
filter unit (not shown). In FIG. 3 the water in pool 11 is at the desired 
level L. Probe 16 is installed in filter basket 51 by removing cap 25 and 
cutting off an appropriate portion of housing 57 such that after cap 25 is 
replaced on housing 57 and probe 16 is positioned in the bottom of basket 
51, line 32 on housing 57 and tip 27 of probe 26 are generally positioned 
at the desired water level L. Wire 17 extends through expansion joint 18 
to control unit 20 (not shown in FIG. 3). Control unit 20, in a manner 
similar to that described in conjunction with FIG. 1, automatically 
controls a valve 33 to direct water through a conduit 36 into pool 11 when 
the level of water 13 therein falls below the desired level L for a 
selected period of time. 
In FIG. 4, probe unit 16 has been secured to the side of pool wall 12 with 
U-shaped clamp 54. The level of water 13 illustrated in FIG. 4 is the 
desired level L of the water. Unit 16 is positioned on wall 12 such that 
line 32 on housing 57 and tip 26 of probe 27 are positioned at the desired 
water level. In FIG. 4, wire 17 lead to control unit 20 (not shown) which, 
in a manner similar to that described in conjunction with FIG. 1, 
automatically controls a valve 33 to direct water through a conduit 36 
into pool 11 when the level of water 13 therein falls below the desired 
level L for a selected period of time. 
FIG. 6 is a block flow diagram which illustrates a typical program or logic 
function executed by the microprocessor in control unit 20 during 
operation of the water level control systems of FIGS. 1, 3 and 4. After 
power to the control unit 20 is turned on 70, the basic control program 
consists of commands to "RESET, START AND INITIALIZE" 71; to determine if 
the "PROBE TIP 27 IS TOUCHING THE WATER" 72; to, when the probe tip 27 is 
not contacting water, "START INTERNAL TIME #1" and "TURN ON LOW WATER LED 
40"; to periodically continually permit internal timer #1 to run for a 
preselected period of time and then determine if the "PROBE HAS TOUCHED 
WATER AGAIN" 74; to, if the probe tip 27 has not touched the water, 
"CONTINUE THE TIME #1 RUNNING FOR A TIME EQUAL TO ONE-HALF OF THE TIME 
SETTING OF DIAL 38" 75; to determine when "TIMER HAS RUN" 76 for a period 
of time equal to one-half of the time setting of dial 38; to, after 
internal time #1 has timed out, "TURN ON WATER VALVE 33 AND TURN ON 
FILLING LED 41" 77; to, after turning on valve 33, "START INTERNAL TIME 
#2" 78; to continually periodically monitor if internal timer #2 has run 
for the period of time selected by dial 38, i.e., to determine if "ELAPSED 
TIME IS EQUAL TO SETTING OF DIAL 38" 79; to, after internal timer #2 has 
run for a period of time equal to the setting of dial 38, "TURN OFF VALVE 
33 AND TURN OFF LED's 40, 41" 80; and, after valve 33 and LED 41 have been 
turned off, to return 81 to command block 72. If during command block 72 
the microprocessor determines that tip 27 of probe unit 16 is touching 
water 13, then the microprocessor repeats 85 the query "IS PROBE TOUCHING 
WATER" after a selected, normally short, period of time has passed. If 
while timer #1 is running for a period of time equal to one-half of the 
time setting of dial 38 the probe tip 27 touches the water, then the 
microprocessor will "RESET TIMER AND TURN OFF LOW WATER LED" 82 and return 
84 to control block 72. If when the microprocessor determines whether 
"TIMER #1 HAS TIMED OUT" 76, the timer has not run for an uninterrupted 
continuous period of time equal to one-half of the time setting of dial 
38, the microprocessor logic returns 83 to control block 74. If when the 
microprocessor queries whether the elapsed time of timer #2 is "EQUAL TO 
DIAL SETTING 38" 79, the continuous uninterrupted elapsed time of timer #2 
is less than and not equal to the time setting of dial 38, then the 
microprocessor repeats 85 the query after a selected, normally short, 
period of time has passed. In FIG. 6, logic blocks 74-76 are intended to 
compensate for waves or wave troughs moving past sensing tip 27 and giving 
a false indication of the level of water or other fluid in a reservoir. 
As would be appreciated by those of skill in the art, probe unit 16 can 
sense water 13 in a reservoir 11 by means other than electrical 
conduction. For instance, a light optic system could be utilized to direct 
a beam of light across s small space at the water sensing tip of the 
probe. When the probe tip was contacting water the light beam would be 
interrupted. When the tip was above and not contacting water 13 in a 
reservoir 11, the light beam would not be interrupted. Further, probe unit 
16 does not have to be physically connected to control unit 20 by 
electrical wiring. Radio or light optic signals from probe unit 16 could 
be generated and transmitted from probe unit 16 to control unit 20 to 
indicate when the tip of the probe was or was not contacting water 13 in 
reservoir 11. 
Having described my invention in such terms as to enable those skilled in 
the art to which it pertains to understand and practice it, and having 
described the presently preferred embodiments thereof,