referring first to fig1 and 13 , a spa 200 , includes wall means , as at 201 , facing toward a water reception zone 202 . the wall means may include a synthetic resinous wall 201a bounding zone 202 . the inner face of the wall means appears at 201b . a plurality of water pumps are associated with the wall means , the pumps indicated generally at 203 , and as spaced about zone 202 . if desired , only one pump may be employed , and any number of pumps may be used . the pump or pumps are oriented to individually receive water intake from zone 202 at intake port or ports 204 , and to discharge water streams 205 into zone 202 , as via discharge ports . such ports are defined by nozzle or nozzles 206 . water pumping structure is indicated by block 207 , in the pump 203 seen in fig1 . note pump housing 203a received in the recess 208 , formed in the wall 201a . it may be retained in position frictionally , or by other means . the water pumps are preferably independently operable , as by drive means associated with each pump and located at the pump . also , the pumps may be operated to vary the rate of pumping action , and the stroke of the pumping element , i . e ., variable as to amplitude and frequency of pumping action , to vary the jets 205 to best use of the bather . in this regard , while the pumps are herein described as operating by reciprocation , it is possible to provide rotary impeller - type pumps having controllably variable impeller rates of rotation , and so long as the jets 205 are directed toward the interior region of the spa , as indicated . control means to control the pumping structure is indicated generally at 210 in fig1 . note the three cables 211a , 211b , and 211c extending respectively to the drivers at the three pumping structures 203 shown for independent control . note the frequency and amplitude controls 210a and 210aa controlling one pump via cable 211a ; frequency and amplitude controls 210b and 210bb controlling a second pump via cable 211b ; and frequency and amplitude controls 210c and 210cc controlling a third pump via cable 211c . on - off switches may be provided in or proximate of the controls 210a , 210aa , 210b , 210bb , 210c , and 210cc , for further selective control , in various combinations of amplitude and frequency of pumping action at different pumps . a spa liner may be employed , as at 212 , and clamped by a pump flange 225 . as a result , a minimum of pumping structure is provided ; no water liner or ducts in wall 201 are needed ; the pumps are individually and independently operable and controllable . in the exemplary drawings 1 - 11 , an electrically powered spa jet unit , referred to generally in fig1 by the reference numeral 10 , is provided for use in a spa 12 or the like , to deliver a discharge jet of water to provide a hydrotherapy massage action . the spa jet unit 10 is typically installed in a side wall 14 of the spa in several selected locations about the spa perimeter and below the normal water fill line . each jet unit 10 represents a relatively compact and substantially self - contained unit , which can be individually controlled by an appropriate control unit 16 , all without requiring complex plumbing flow conduit networks and related recirculation pump devices . in general terms , the spa jet unit 10 of the present invention includes an electrically powered reciprocal element 18 adapted for regulation by the control unit 16 to deliver a pulsating jet of water through a discharge nozzle 20 . each jet unit 10 is adapted for mounting into an open - sided pocket 22 formed in the side wall 14 of the spa 12 , with appropriate electrical conductors 24 interconnecting each jet unit 10 to the control unit 16 . no plumbing conduits or related recirculating equipment is required . as a result , the overall hydrotherapy massage system is relatively simple and economical . the spa jet unit 10 is shown in one preferred form in more detail in fig2 - 5 . as shown , the jet unit 20 comprises a generally cup - shaped outer housing 26 adapted for slide - fit reception into the side wall pocket 22 , with the reciprocal element 18 comprising a solenoid mounted on a base wall 27 of the housing 26 . the solenoid 18 includes a reciprocal plunger 28 having a free end contacting and preferably connected to a central region of a resilient diaphragm 30 formed from a suitable elastomeric material . an outer rim of the diaphragm 30 is trapped or retained against the periphery of the housing base wall 27 by a retainer sleeve 32 mounted within the outer housing 26 , as by means of a threaded interconnection therebetween . a port sleeve 34 is mounted in turn within the retainer sleeve 32 , as by a further threaded connection therebetween . the port sleeve 34 defines a port wall 36 , which extends across the interior of the spa jet unit in a position spaced forwardly from a normal , unstressed position of the diaphragm 30 . thus , the port sleeve 34 cooperates with the diaphragm 30 to define a pump chamber 38 for the spa jet unit . a plurality of intake ports 40 are formed in the port wall 36 in a circular pattern about the centrally positioned discharge nozzle 20 , which is also formed in the port wall 36 . importantly , the rear or inboard sides of the intake ports 40 are normally covered by resilient valve flaps 42 , which are retained between an inboard end of the port sleeve 34 and a short flange 44 formed on the retainer sleeve 32 . as shown in fig4 and 5 , reciprocal operation of the solenoid 18 is effective to draw water from the spa into the pump chamber 38 ( fig5 ), and then to discharge that water as the pressure discharge jet through the nozzle 20 ( fig4 ). more particularly , as shown in fig4 movement of the solenoid plunger 28 through an advance stroke depicted by arrow 46 expels water from the pump chamber 38 in the form of a discharge jet passing outwardly through the nozzle 20 . during this stroke movement , the water pressure within the chamber 38 effectively retains the valve flaps 42 in a closed position , thereby confining water discharge to passage through the nozzle 20 . subsequent movement of the plunger 28 through a retraction stroke , as depicted by arrow 47 in fig5 causes the diaphragm 30 to flex rearwardly , resulting in a momentary vacuum within the chamber 38 , whereby water is drawn from the spa into the pump chamber 38 through the intake ports 40 , as well as via the nozzle 20 . fig5 shows pressure - caused retraction of the valve flaps 42 to accommodate relatively free inflow of water through intake ports 40 into the pump chamber 38 . the control unit 16 ( fig1 ) includes appropriate controller components for regulating the operation of the solenoid 18 in a manner achieving adjustable discharge jet power and pulse rate . for example , a pulse width modulator with frequency control may be used for regulating the reciprocating frequency and / or stroke length of the solenoid 18 , according to the preferences of an individual using the spa . alternately , pulse width modulation systems may be employed to achieve a range of power and frequency selection , which can be programmed through variable speed frequencies . the control unit 16 may be used for common control of multiple spa jet units 10 , or otherwise adapted to individually control each spa jet unit . fig6 illustrates one alternative form of the invention wherein components identical to those shown and described in fig1 - 5 are referred to by common reference numerals . fig6 differs from the embodiment of fig1 - 5 in that a small flow of water is employed to cool the solenoid 18 , thereby preventing overheating thereof during operation . as shown , this small water flow is obtained by providing a small circulation tube 48 with an inlet end tapped into the pump chamber 38 . the circulation tubing 48 includes a coil segment 49 wrapped about the winding portion of the solenoid 18 in heat transfer relation therewith , and then extends to a discharge end connected to the region in front of the port wall 36 . during reciprocal solenoid operation , a small portion of the water under pressure within the pump chamber 38 is forced to flow through the circulation conduit 48 to cool the solenoid . fig7 shows another alternative form of the invention wherein a modified reciprocal element 118 is provided in lieu of the solenoid device shown in fig1 - 6 . in this version , an electric motor 50 is mounted on the base wall 27 of the outer housing 26 , and includes a rotary output shaft 52 connected by a pair of crank links 54 and 55 to a head 56 coupled to the diaphragm 30 , in the same manner as previously described with respect to the is solenoid plunger 28 . operation of the motor 50 displaces the crank links 55 and 55 in a manner providing the desirable reciprocal action of the diaphragm 30 , as previously described . fig8 shows a further alternative form of the invention , generally in accordance with fig1 - 5 , except for the inclusion of an air induction system 58 . the structural components shown in fig8 are otherwise identical to those shown and described in fig1 - 5 , and are thus identified by common reference numerals . the air induction system 58 comprises an air induction tube 60 having one end coupled to ambient air , and an opposite end tapped into the pump chamber 38 . a one way check valve 62 is mounted along the air tube 60 to permit air inflow to the pump chamber 38 , while preventing water backflow through the air tube . a control valve 64 may be provided to regulate air flow through the air tube 60 . during operation , and upon retraction motion of the diaphragm 30 to draw water into the pump chamber 38 , the momentary vacuum in the pump chamber 38 additionally draws air therein via the air tube 60 . as a result , a quantity of air is entrained with the water within the pump chamber 38 , for discharge with the water as an air - water jet during subsequent advance stroke motion of the diaphragm 30 . the combined air - water jet is known to provide an enhanced therapeutic massage action . fig9 illustrates an alternative air induction system 158 wherein the back or inboard side of the diaphragm 30 cooperates with the housing base wall 27 to define an air chamber 66 for pumping air into the spa jet unit . in this version , an air tube 160 with a check valve 162 therein is provided for drawing air into the air chamber 66 each time the diaphragm 30 is displaced forwardly by the solenoid 18 . subsequent retraction of the diaphragm 30 is effective to expel air from the chamber 66 through a tube segment 68 and associated check valve 70 for passage into the pump chamber 38 and entrainment with water therein . a bleed tube 72 may be connected into the tube segment 68 , and equipped with an adjustable valve 74 for regulating the amount of air injected into the pump chamber 38 . air injected into the pump chamber is , of course , expelled with the water as a combined air - water jet through the forward nozzle 20 . fig1 and 11 show still another alternative embodiment of the invention wherein components corresponding in structure and function to those shown and described in fig1 - 5 are identified by common reference numerals . in this embodiment , a cup - shaped outer housing 26 has a solenoid 18 carried by a base wall 27 thereof , with a reciprocal plunger 28 coupled to a pumping piston 75 . the piston 75 comprises a circular plate having an annular array of pump ports 76 formed therein , with the outboard side of the ports 76 being normally covered by a resilient flap valve 78 , the center of which is secured in a suitable manner to the pump piston 75 . the piston 75 is reciprocally carried within a cylinder 80 and cooperates with a front wall 81 of the cylinder 80 to define the pump chamber 38 . the pump chamber is open to the body of water within the spa through a forward discharge nozzle 20 , which may include a narrow central jet port 82 . as shown , the outboard side of the spa jet unit includes a perforated cover plate 84 , which cooperates with the nozzle 20 to retain an angularly adjustable nozzle fitting 86 . an air induction tube 88 is coupled to the interior of the nozzle 20 , at the downstream side of the jet 82 , to permit entrainment of air therein in response to water pumping through the nozzle 20 . advancement of the solenoid plunger 28 displaces the pump piston 75 in a forward direction within the pump chamber 38 , to displace water therein as a discharge jet outwardly through the nozzle 20 and associated nozzle fitting 86 . during this discharge step , the flap valve 78 sealingly overlies the piston ports 76 , so that the water in the pump chamber 38 is forced outwardly into the spa ( fig1 ). while a peripheral seal may be provided between the pump piston 75 and the inner diameter of the cylinder 80 , a small clearance between these elements will normally suffice to provide the desired pumping function . subsequent retraction of the solenoid plunger 28 draws the piston 75 rearwardly within the cylinder 80 . in this regard , the inboard side of the pump piston 75 and the cylinder 80 is in open flow communication with the perforated coverplate 84 , around the periphery of the cylinder 80 , so that water behind the piston 75 is allowed to displace forwardly through the pump ports 76 into the pump chamber 38 . the flap valve 78 flexes forwardly ( fig1 ) as the piston is drawn rearwardly by the plunger 28 , to allow the water to flow through the pump piston 75 . accordingly , reciprocal driving of the piston 75 within the cylinder 80 affectively discharges a water jet through the nozzle 20 and nozzle fitting 86 , in a pulsating fashion , to provide a desirable therapeutic massage action . fig1 also shows the pump unit in discharge motion , the flow channels 89 having water flowing in an inwardly direction , as marked by the arrows and toward chamber 189 rearwardly of the reciprocating elements 75 and 78 . this flow is in opposite direction to the flow through the central jet port 82 , as marked by the arrow and is a result of a negative pressure created rearwardly of element 75 as the element moves forwardly in the discharge motion . with proper design , these flows are balanced to cancel or reduce momentum forces transmitted to the spa or tub wall . referring to fig1 , it shows the pump unit in retraction motion . flap seal 78 opens to allow free fluid movement through the reciprocating element . no substantial fluid movement is produced through central jet port 82 or through flow channels 89 . fig1 shows an embodiment wherein the reciprocating element 220 drives end wall 221a of a bellows 221 in reciprocation , to draw fluid into chamber 222 via ports 223 and passage 224 , and to discharge fluid through passage 224 . the bellows also provides a seal connection to chamber wall 225 , to seal off and protect the solenoid 226 from the water . a return spring is used at 227 . in devices as described , the housing may consist of a material which readily transmits heat causing a thermal connection between the solenoid and water in order to cool the solenoid . a variety of further modifications and improvements to the spa jet unit of the present invention will be apparent to persons skilled in the art . accordingly , no limitation on the invention is intended by way of the foregoing description and accompanying drawings , except as set forth in the appended claims . referring now to fig1 and 16 , the structure shown is somewhat similar to fig1 and 11 . the upright wall of the spa or tub 300 is indicated at 301 , and may consist of synthetic resinous material . a cup - shaped outer housing 302 may also consist of synthetic resinous material . it is set or received into a recess 303 formed in wall 301 opening toward the water - filled spa interior zone 304 . housing flange 302a fits against the wall inner side 301a . water delivery structure is received into the housing to deliver water into zone 304 . such structure , in the example , includes a driver 306 , for reciprocating a plunger 307 in the directions indicated by arrows 308 . a pumping piston 309 is coupled to the plunger and may comprise a circular plate . the piston defines a water - displacing reciprocating element operable to move rightwardly in fig1 , to draw water into an inner chamber 311 at the front side of the plunger , as via a water flow inlet / outlet hole 312 in a chamber front wall 313 . the periphery of the plate extends adjacent and reciprocates adjacent the fixed chamber skirt 311a . as the piston or plate 309 moves leftwardly , it displaces water from chamber 311 through the hole 312 toward and into the spa interior . water also flows to the rear side 311a &# 39 ; of the piston 309 , as via an outer passage 317 extending outwardly of and about the inner chamber 311 , i . e ., it fills the space 314 between the driver 306 and the piston 309 , serving to at least partly balance the water masses being moved by the piston as it reciprocates . this reduces vibration transmitted to the spa wall 301 . a front plate 315 extends forwardly of wall 313 , to define a water flow passage 318 communicating between passage 317 and the inlet / outlet hole 312 . plate 315 carries a diffuser 320 having a forwardly tapering conical wall , and in axial alignment with hole 312 . plate 315 has a skirt 315a attached as via threading 322 to the housing 302 , and a bezel 315b overlying flange 302a . a permanent magnet 325 is carried by a rotatable ring 326 received into the front plate and skirt recess 327 , and can be finger gripped by the bather in the tub or spa water to adjustably rotate the ring and magnet , and relative to a sensor 328 . the sensor is shown as isolated from the water into the spa , by virtue of its spacing from the water - receiving zone or zones , as shown . for example , the sensor can be embedded in the housing 302 , radially outwardly of the path of rotation of the magnet . as the magnet is rotated , its magnetic field projected outwardly toward the sensor is detected with varying strength as a function of magnet rotation . accordingly , the output signal developed by the sensor has correspondingly varying amplitude , or other parameter . a connection is shown at 330 from the sensor to the driver , and may , for example , vary the pushing output of the driver to vary the pumping effect of the piston , thereby varying the water jet output from the hole or jet opening 312 to the spa interior , as via the diffuser . a magnetic sensor , or a hall effect sensor , may , for example , be employed , as previously discussed . fig2 and 24 show the forward and rearward water flow characteristics when a diffuser is used ; whereas , fig2 and 22 show such flow characteristics when a diffuser is not utilized . fig1 and 18 show the same structure as in fig1 and 16 , except for the use of multiple sensors in the form of a series of reed switches 340 , spaced apart circularly about the axis of the adjustable carrier ring 326 . the magnetically sensitive reed switches are connected at 341 to the drive control , so that as rotation of the magnet 325 causes different ones of the switches to close , the output pulse rate of the drive can be stepwise varied . one or more such reed switches can be used . fig2 shows the tendency for the outward flow to maintain a confined &# 34 ; jet stream &# 34 ; perpendicular to the hole . fig2 shows the flow pattern of a liquid flowing into a hole d . the direction of the fluid flow is mainly hemispherical , not streamlike as in fig2 . in fig2 , a diffuser a has been placed above the hole and in axial alignment with the hole . the jet stream , as it passes through the diffuser , entrains fluid , which flows in through openings b between the diffuser base and plate 313 , and then flows through opening c . the net effect is to increase the overall volume of fluid in the jet stream , but also to reduce its velocity . this dampens the maximum pressure pulse , resulting in a softer feel of water impinging on the bather &# 39 ; s skin . in fig2 , fluid flow is shown passing reversely through 312 , at the hole d . fluid motion up through the diffuser persists , although diminished . the result is continuous flow through diffuser opening c , even during the inward flow period . the result of placing the diffuser over a hole or nozzle with an alternating inward / outward flow is to soften the pulsating effect and give somewhat of a continuous flow pleasing to the bather . fig1 and 20 show an actual application of the diffuser to the nozzle of the structure shown . in this case , the diffuser 420 is made to be axially adjustable by threaded connection at 350 between diffuser annular inner portion 420b and the tapered tubular portion 320 of plate 313 . in the full open position seen in fig1 , water is entrained in through the diffuser as discussed above , in regard to fig2 . in fig2 , the diffuser is adjusted to the right to be in the closed position , so that there is no opening to allow water entrainment into the jet stream . in the closed position , it has no effect on the jet stream . by turning the diffuser , the bather is able to increase or decrease the size of the opening between the diffuser and the nozzle plate , which reduces to varying the variations in velocity and pressure amounts over a pulse cycle , and reduces the peak velocity and peak pressure . the control devices of fig1 - 20 can be employed with any of the pumping devices shown in the various drawings . the device of fig1 and 16 , and equivalents , may be considered as preferred .
a spa water delivery system , the spa includes a wall structure exposed to a water reception zone , and combination comprising : a water delivery structure associated with the wall structure to deliver water to the zone ; a manually operable signaling device carried by the wall structure to be operated by a bather in the water reception zone ; a sensor spaced from the signaling device to be out of contact with spa water , and responsive to operation of the signaling device to produce a control signal ; whereby the control signal may be used to control a flow characteristic of water flowing via the delivery structure to the zone .