Patent Publication Number: US-7895682-B1

Title: Toilet ventilation system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is concerned with the removal of odors coincident with disposal of human bodily wastes into a toilet porcelain bowl having a hinged seat by supply of negative pressure in ventilation thereof. 
     2. General Background 
     The modern flush toilet, invented by John Crapper, is first recognized as being the single most important amenity of modern civilization without which widespread disease and the prevalent odor of human feces in the streets of all cities would remain in oppression of urban humanity. Chorea, typhoid, dysentery and other deadly diseases have been virtually eradicated from civilization by the invention of John Crapper and the usage of associated sewage systems. 
     The repeated outbreak of chorea in Chicago in the 1870s and 80s resulting in the last instance of over 30,000 deaths is testimony to the importance of modern sanitation systems as is its solution: the reversal of the South Branch of the Chicago River and its continuation through the Chicago Sanitary and Shipping Canal from Calumet to the Mississippi River. This, and the ‘deep tunnels’ providing Manhattan with both potable water from hundreds of miles upstate and sewage disposal for Gotham denizens, are among the largest and most important engineering feats of the modern age. Uncounted dozens died in the creation of the latter and more continue to perish in building its replacement. 
     At the present time perhaps the most pervasive reminder of the threat posed by unsatisfactory disposal of human excrement is the odor associated with disposal of the same into the porcelain bowl of a modern flush toilet while sitting upon the generally flat and annularly ovoid shaped hinged seat disposed in parallel, and in spaced apart contact with, the generally flat top surface of the porcelain bowl. Exhaust ventilation of the room having this facility will succeed in preventing the migration of these noxious odors beyond the confines of the same but, obviously, fails to prevent the author of the odors from subjugation to this most unpleasant assault upon the olfactory senses. It is noted that the repulsion triggered through the olfactory system of the human body by these odors is a defense mechanism as human feces carries deadly pathogens and therefore this repulsion is generally universal to the human species and decidedly severe. 
     3. Discussion of the Prior Art 
     A large number of U.S. patents are known to attempt address of the present problem. In chronological order since the commencement of the latest millennium, as commonly if incorrectly understood to begin with Jan. 1, 2000, one has: 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                 U.S.  
                   
                   
               
               
                 # 
                 Pat. No. 
                 Inventor 
                 Title 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 1 
                 6,019,862 
                 Carwell et al. 
                 Method of Making Integrated 
               
               
                   
                   
                   
                 Toilet Bowl Exhaust System; 
               
               
                 2 
                 6,029,286 
                 Funk 
                 Odor Removing Apparatus for Toilets; 
               
               
                 3 
                 6,041,449 
                 Brown et al. 
                 Apparatus and Method for 
               
               
                   
                   
                   
                 Treating Objectionable Odors in 
               
               
                   
                   
                   
                 Toilet Bowls and the Like; 
               
               
                 4 
                 6,073,273 
                 Tillen 
                 Venting Apparatus for Flush Toilets; 
               
               
                 5 
                 6,158,058 
                 Martens 
                 Ventilated Toilet; 
               
               
                 6 
                 6,167,576 
                 Sollami 
                 Ventilated Toilet Seat; 
               
               
                 7 
                 6,173,453 
                 Shahar 
                 Toilet Venting System; 
               
               
                 8 
                 6,209,146 
                 Gonzalez 
                 Ventilation Device for a Toilet; 
               
               
                 9 
                 6,219,853  
                 Johnson 
                 Toilet Ventilation System; 
               
               
                 10 
                 6,052,837  
                 Norton et al. 
                 Toilet Ventilation System; 
               
               
                 11 
                 6,233,750  
                 Donald et al. 
                 Toilet Bowl Ventilating Apparatus; 
               
               
                 12 
                 6,279,173  
                 Denzin et al. 
                 Devices and Methods for Toilet 
               
               
                   
                   
                   
                 Ventilation Using Radar Sensor; 
               
               
                 13 
                 6,295,656 
                 Tillen 
                 Venting Apparatus for Flush Toilets; 
               
               
                 14 
                 6,298,500  
                 Sollami 
                 Ventilated Toilet Seat; 
               
               
                 15 
                 6,360,377 
                 Sollami 
                 Filtration Housing Unit for Use with 
               
               
                   
                   
                   
                 a Ventilated Toilet Seat; 
               
               
                 16 
                 6,363,542  
                 Pope, Sr. 
                 Toilet Ventilator; 
               
               
                 17 
                 6,367,092  
                 Carwell et al.  
                 Charge Transfer Capacitance 
               
               
                   
                   
                   
                 Sensing and Control System 
               
               
                   
                   
                   
                 for an Integrated Venting System; 
               
               
                 18 
                 6,370,702 
                 Iddings, Sr. 
                 Toilet Enclosure with Ventilation 
               
               
                   
                   
                   
                 System; 
               
               
                 19 
                 6,370,703  
                 Kim et al. 
                 Odorless Toilet; 
               
               
                 20 
                 6,457,186  
                 Stewart 
                 Air Cleaning Device for a Toilet Seat. 
               
               
                   
               
            
           
         
       
     
     4. Statement of Need 
     At least twenty U.S. patents attempting to address the problem of noxious odors associated with the disposal of human bodily wastes into the porcelain bowl of a modern flush toilet while sitting on the hinged seat to the same have issued within less than three years prior to the present writing. The number and frequency of these is considered testimony to the pervasiveness, severity, and persistence of the problem. A poignant need for an effective means of removing the odor associated with disposal of human bodily wastes into the porcelain bowl of a modern flush toilet while sitting upon the hinged seat of the same is hence considered to exist. 
     SUMMARY OF THE INVENTION 
     Objects of the Invention 
     The encompassing object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowl of a modern flush toilet whilst sitting upon the hinged seat of the same. 
     A first auxiliary object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowl of a modern flush toilet whilst sitting upon the hinged seat of the same in a manner that introduces no safety hazards. 
     A second auxiliary object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowl of a modern flush toilet whilst sitting upon the hinged seat of the same in a manner that is unobtrusive to the user. 
     A third auxiliary object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowl of a modern flush toilet whilst sitting upon the hinged seat of the same in a manner that is applicable to a large range of sizes of toilet. 
     A fourth auxiliary object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowl of a modern flush toilet whilst sitting upon the hinged seat of the same in a manner that minimizes duct work required of installation. 
     A fifth auxiliary object of the present invention is the removal of odors associated with the disposal of human bodily waste into the porcelain bowls of a plurality of flush toilets in a building whilst sitting upon the hinged seat of any of the same. 
     Other ancillary objects of the present invention include automatic activation and applicability to both residential and commercial buildings. 
     In achievement of the above stated objects of the present invention it is suggested that a negative pressure differential with respect to ambient be applied proximate the back of the top of the porcelain bowl of a standard flush toilet, that a remote blower be used to supply this negative pressure differential, and that the remote blower be connected by conduit to a manifold adapted to possess an appropriately located and disposed inlet. 
     It is suggested that the standard spacing between the mounting bolts connecting the hinged seat, and typically a hinged lid also, be utilized for location of the manifold and its inlet specifically utilizing two slots, one each presented by opposed lateral wings, each possessing a width sufficient to admit one said mounting bolt. The manifold can then be readily located for use upon any flush toilet having standard spacing between the bolts utilized for connection of a hinged seat thereto. It is also suggested that the manifold inlet possess a sufficiently diminutive height for allowing location between the top annular substantially flat surface of the porcelain bowl and the bottom flat surface of the hinged seat without replacement of the existing bolts or seat. 
     It is suggested that relatively small, in comparison with typical rectangular cross section ventilation duct work, annular cross section, i.e. round, conduit be utilized between the manifold and the remotely located blower. It is specifically suggested that standard polyvinyl chloride (PVC) schedule 40 piping with an interior diameter of about one and one half inches be utilized throughout both residential and commercial applications. This enables the conduit to be disposed in plumbing passageways and to be hung within wall frames by the sill. It is suggested that the remotely located blower be located in a housing facilitating multiple conduit connections for a plurality of manifolds each located upon a separate flush toilet within the same building. And it is suggested that an adapter be utilized for connection of lengths of conduit of differing cross section to each other and the blower housing. 
     In optimization of the air flow dynamics of the inlet of the manifold proximate the top surface of the porcelain bowl of a typical flush toilet, and in accommodation of the varying depth dimensions from fore to aft of these porcelain bowls, it is suggested that a hood possessing a pair of slots spaced apart the same distance as the two slots on the manifold, i.e. the standard distance between the bolts connecting the hinged seat to the porcelain bowl, be provided. The hood can extend over a rear portion of the top of the interior of the porcelain bowl and the inlet of the manifold proper be disposed between the top substantially flat surface of the porcelain bowl and the bottom flat surface of the hinged seat spaced apart substantially in parallel thereabove. 
     It is suggested that the manifold and the hood both be constructed in plastic. This, and the use of a remote blower and plastic conduit, are considered to minimize any potential problems regarding corrosion or unwanted conduction of electricity occasioned by proximity to water in the porcelain bowl of a human waste disposal flush toilet or any other water in the room in which said toilet is located. Use of a blower remote from the porcelain bowl of a flush toilet, and from any and all sources of water in the room in which the toilet is located, minimizes the safety hazard otherwise poised by location of standard alternating current supplied electrical motors in the same room. 
     It is suggested that electrical supply to the remote blower be activated by a wall mounted light switch for the room in which each flush toilet with a manifold attached thereto is located and that the separate vent for excessive humidity commonly required for bathrooms having a shower or bath be connected via conduit to the remote blower exhausting to the exterior of the building through conduit connected to an exhaust port of the blower housing. 
     Flexible hose connecting the manifold to the rigid conduit is further suggested to facilitate ease in installation. Use of either: (a) annular barbs upon a manifold extension and a hose clamp for conventional connection; or (b) a rigid fastened flanged hose connection to the manifold outlet facilitating quick and easy disconnection are suggested. 
     Other advantages and benefits of preferred embodiment of the principles relating to the present invention may be appreciated in the detailed description following; particularly if conducted with reference to the drawings attached hereto briefly described immediately below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a system in preferred accordance with the principles relating to the present invention providing a plurality of ordinary flush toilets in a single building with noxious odor removal. 
         FIG. 2  is an isometric view of a manifold in preferred accordance with the principles relating to the present invention. 
         FIG. 3  is an isometric view of a hood in preferred accordance with the principles relating to the present invention. 
         FIG. 4  is an isometric view of a blower housing in preferred accordance with the principles relating to the present invention including depiction of a dual size conduit connector on an inlet port. 
         FIG. 5  is a plain elevational detail view taken from a side of a flanged conduit connection. 
         FIG. 6  is a plain elevational detail view taken from the bottom of a portion of the manifold extension illustrating a sensor port therethrough. 
         FIG. 7  is a plain elevational view taken from a side of an adapter for lengths of conduit possessing differing sizes used as a hanger in a frame sill of a wall for hanging schedule 40 PVC conduit therein. 
         FIG. 8  is an isometric view of the back of the blower housing depicted in  FIG. 4  depicting a regulator. 
         FIG. 9  is an isometric view of a blower housing similar to that depicted in  FIG. 4  having a rectangular exhaust port. 
     
    
    
     
       
         
           
               
             
               
                   
               
               
                 NOMENCLATURE 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 10 
                 flush toilet 
               
               
                 11 
                 manifold 
               
               
                 12 
                 blower housing 
               
               
                 13  
                 hood 
               
               
                 15 
                 manifold inlet 
               
               
                 16 
                 wing 
               
               
                 17 
                 slot 
               
               
                 19  
                 manifold outlet 
               
               
                 20 
                 blower 
               
               
                 21 
                 exhaust port 
               
               
                 22 
                 inlet port 
               
               
                 23 
                 sleeve 
               
               
                 25 
                 dual size conduit inlet port 
               
               
                 26 
                 reduction plate 
               
               
                 27 
                 flange 
               
               
                 29 
                 bolt hole 
               
               
                 30 
                 conduit 
               
               
                 31 
                 annular barbs 
               
               
                 32 
                 fore edge 
               
               
                 33  
                 rear edge 
               
               
                 35 
                 manifold plenum 
               
               
                 36 
                 medial section 
               
               
                 37 
                 hose connector 
               
               
                 39 
                 manifold extension 
               
               
                 50 
                 annular projection 
               
               
                 51 
                 gasket 
               
               
                 52 
                 sensor port 
               
               
                 53 
                 adapter 
               
               
                 55 
                 vent 
               
               
                 56 
                 light switch 
               
               
                 57 
                 vertical vanes 
               
               
                 59 
                 aperture 
               
               
                 60 
                 hanger 
               
               
                 61 
                 female end 
               
               
                 62 
                 shoulder 
               
               
                 63 
                 frame sill 
               
               
                 65 
                 wiring 
               
               
                 66 
                 relay 
               
               
                 67 
                 circuit board 
               
               
                 69 
                 power supply 
               
               
                 70 
                 regulator 
               
               
                 71 
                 orifice 
               
               
                 72 
                 door 
               
               
                 73 
                 handle 
               
               
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
       FIG. 1  schematically depicts a ventilation system in preferred accordance with the principles relating to the present invention operative upon a plurality of flush toilets  10  each possessing a porcelain bowl with a substantially flat top surface and a seat hinged thereto possessing a flat bottom disposed, in operative position, substantially parallel to and spaced apart from the top surface of the porcelain bowl. The porcelain bowl, seat, and other components of the flush toilets  10  are well known and are hence undepicted in the drawings attached hereto. The size of the porcelain bowls vary, particularly in depth from front to rear including the cavity thereto and incidentally the associated seats, and a hood  13  adjustable during installation with respect to a manifold inlet  15  disposed at the back of the space between the top surface of the porcelain bowl and the bottom surface of the hinged seat accommodates this variation. Perhaps most importantly, it is noted that the hinged seat of a standard flush toilet  10  in the U.S.A. is attached to the porcelain bowl by a pair of mounting bolts that are spaced apart from each other a standard distance of five and one half inches center to center regardless of the size. 
     The conduit  30  seen in  FIG. 1  also is simply represented as no depiction is considered necessary or desirable. The conduit  30  utilized in preferred embodiment of the principles relating to the present invention is well known and requires no modification: Schedule 40 PVC piping with an internal diameter (ID) of approximately one and a half inches (1.5″). Use of flexible hose that can be fitted, and preferably glued, to this PVC piping is recommended for connection of the manifold outlet  19  depicted in  FIG. 2  to this conduit  30  and annular barbs  31  provided for this. Alternatively, or in addition, a standard hose clamp of appropriate diameter, i.e. about one and seven eighths inches (1.875″) can be tightened about the flexible hose on either connection of the hose ends. 
     The most preferred connection of the manifold outlet  19  to the conduit  30  uses PVC flexible hose that can be effectively glued to PVC conduit or PVC connectors and a hose connector  37  facilitating a quicker and easier manual disconnection, preferably without the use of tools, than achievable with use of a hose clamp with or without annular barbs  31  on the manifold extension  39  or a conduit  30  connector. 
     A hose connector  37  is seen  FIG. 5  to have an annular projection  50  possessing an exterior adapted to engage the interior of the flexible hose and has flanges  27  butted against the flanges  27  of the manifold extension  39 . It is recommended that the hose connector  37  be made of PVC, that a resilient gasket  51  possessing a matching ID be disposed therebetween to ensure an air tight seal and that appropriate fasteners, not shown, such as a pair of toggle clamps or wide pitch bolts and wing nuts, be used to fasten the two opposed pairs of flanges  27  together with the fasteners passed through the bolt holes  29  in the flanges  27 . It is suggested that flexible PVC hose be used so it can be effectively glued to the annular projection  50  and hose clamps are unnecessary to secure the connection. It is emphasized that this connection of the manifold outlet  19  to the conduit  30  may be by any means desired, that any functional equivalent fulfills the principles of the present invention. 
     It is also emphasized that schedule 40 PVC piping comprises the preferred conduit  30  but other sizes and other materials will suffice to fulfill the necessary function of the conduit  30  in preferred embodiment of the principles relating to the present invention. It is also suggested that round, preferably three inch (3″) ID, metal duct be used in connection to the inlet ports  22  and exhaust port  21  particularly on the blower housing  12  in commercial buildings as in standard practice. The exhaust in any case is to the exterior of the building through conduit  30 . The use of larger diameter conduit  30  from the exhaust port  21  of a blower housing  12 , or the blower  20  directly, reduces back pressure considerably upon the blower  20 , and improves system performance. 
     It is commented that staged increases in the size of the air path are observed in a system in preferred accordance with the principles relating to the present invention facilitating effective supply of negative pressure differentials to a plurality of manifold inlets  15  using a single blower  20  located in a single blower housing  12 . The manifold inlets  15  are of lesser area than schedule 40 PVC conduit  30 , as demonstrated further below, and 3″ diameter metal duct has an interior area that is much larger still. It is further considered desirable to accommodate use of both sizes of these types of conduit  30  in connection to the blower housing  12 . A dual size conduit inlet port  25  comprised of: a reduction plate  26  with an aperture  59  for disposition of a male/female PVC connector; a gasket  51 ; and a 3″ diameter sleeve  23  with a annular flange  27  as depicted in  FIG. 4  on one of the inlet ports  22  of the blower housing  12  facilitates fixed connection of either schedule 40 PVC or 3″ diameter metal conduit  30 . 
     The annular flange  27  of the sleeve  23  is seen to possess a plurality of bolt holes  29  intended to match a set of bolt holes  29  of the same pattern through the wall of the blower housing  12 , the reduction plate  26 , and the gasket  51  fitted between the reduction plate  26  and the exterior surface of the wall of the blower housing  12  with sheet metal bolts acting upon the flange  27  of the sleeve  23  and compressing the assembly together in fastening the same with engagement of the bolt holes  29  in the wall of the blower housing  12 . All of the bolt holes  29  here have the same pattern but the set through the wall of the blower housing  12  are intended to have a diameter approximating the root diameter of the bolts used while the other bolt holes  29  are intended to have a diameter allowing free passage of the greater full thread diameter of the bolts used. Ordinary sheet metal bolts or screws are suggested. 
     The blower housing  12  seen in  FIG. 4  is preferably constructed in sheet metal. A blower  20  is preferably bolted in position inside the blower housing  12  using the bolt holes  29  seen in  FIG. 4  on either side of the exhaust port  21 . An external sleeve  23  may also be seen projecting outwardly from the exhaust port  21  and is intended to be fitted interiorly to the conduit  30  used for exhaust in a conventional manner preferably using 3″ metal conduit  30 . Installation of a length of PVC conduit  30  into an inlet port  22  using the aperture  59  provided by the reduction plate  26  can use an ordinary male to female PVC connector, not shown, disposing the male end through the aperture  59  and pulling the shoulder of the connector against the exterior surface of the reduction plate  26  with a lock ring, also not shown) threaded onto the male end of the connector and tightened against the interior surface of the reduction plate  26 . 
     The blower housing  12  may have any desired number of inlet ports  22  and the inlet ports  22  that are unused can simply be closed by plugs, not shown, that can be threaded to be engaged by a lock ring and extend interiorly against a positive stop created by a flange  27 . Or, more simply, a flanged metal plug with compressible insert can be utilized or any other type of fire proof plug preferably avoiding the use of duct tape although this also will obviously suffice to seal the blower housing  12 . It is expected that the blower  20  will need to be sized to economically provide the negative pressure for all the manifolds  11  concerned. A sensor port  52 , as earlier mentioned, is considered very useful for this. 
     The adapter  53  depicted in  FIG. 7  is specifically suited to adapt schedule 40 PVC piping preferred for use as conduit  30  wherever possible in a system in preferred accordance with the principles relating to the present invention. In most residential structures this is the only type of conduit  30  preferred except for flexible hose connecting to the manifold extension  39  and ordinary 3″ diameter metal duct for exhaust. It is noted that a blower housing  12  isn&#39;t strictly necessary although increasing the area of the airway, particularly behind the blower  20 , is desirable to minimize back pressure and in order to minimize expense it is hence recommended that schedule PVC conduit  30  be used up to the blower  20  or blower housing  12  and 3″ diameter metal duct for exhaust. 
     An adapter  53  such as that shown in  FIG. 7  be used to connect the PVC conduit  30  on one side to metal conduit  30  on the other side if it is desired to run 3″ diameter metal conduit  30  through a building plenum to the blower housing  12 . The metal conduit  30  recommended is ordinary galvanized mild steel ducting. Square or rectangular metal duct can also be used. Extensive engineering has been conducted especially with regard to the use of schedule 40 PVC piping as the conduit  30  conveying the negative pressure created by a blower  20  in a blower housing  12  to a manifold  11  as specifically depicted in the drawing figures attached hereto and, in brief, satisfactory air flow for several relatively long lengths of conduit  30  including that for several vents  55  is readily obtained although this is perhaps contrary to conventional expectations. 
     Schedule 40 PVC piping is very inexpensive and can be run through plumbing passageways, including the space within the frame of a wall, while standard large rectangular metal duct cannot. This is considered to provide a valuable attribute regardless of whether the building concerned is commercial or residential as use of schedule 40 PVC enables the conduit  30  to be hung from the frame sill  63  of a wall as depicted in  FIG. 7 . The hanger  60  shown therein uses an adapter  53  with one female end  61 , i.e. tapped, and a tapered shoulder  62  of greater diameter than the aperture  59  cut through the frame sill  63  and sized to permit passage of the female end  61 . The upper end of a measured length of schedule 40 PVC conduit  30  is placed through the aperture  59  in the frame sill  63  and threaded into a female end  61 , preferably by threading and glueing, and is dropped into position. 
     It is noted that exhaust ventilation only required in the U.S.A. to disperse excessive humidity or fog commonly created by a hot shower or bath. An internal blower without any exhaust venting, often combined with an electrical resistive heating element, is hence a commonplace in bathrooms. A ‘bathroom’ having a flush toilet  10  but no shower or bathtub is not required to have any ventilation. 
     Lavatories in commercial buildings having many flush toilets  10  but no shower or bathtub are not required by code to have ventilation. In these cases a system in accordance with the principles relating to the present invention remedies an obvious problem. In cases wherein a true vent  55  exists or is intended for a ‘bathroom’ or lavatory possessing at least one flush toilet  10  it is suggested that the duct for the same be combined with the conduit  30  of the present invention. For the purposes of meeting building code requirements in the U.S. it is noted that 50 cubic feet per minute of air flow is required and that the air flow through the manifold inlet  15  and the vent  55  may be combined to meet this requirement and hence a single conduit  30  and remote blower  20  for the ‘bathroom’ suffice. 
     The blower  20  represented in  FIG. 1  is also a well known component, a purchased item, and is hence also undepicted in the drawings attached hereto. The blower  20  requires an electrical power supply  69  and is remotely located with respect to the manifold  11 . It is recommended blower  20  operation be controlled with operation of a light switch  56  in the rooms possessing flush toilets  10  and that a circuit board  67 , at least one relay  66  and appropriate wiring  65  be utilized. And if the conduit  30  conveying negative pressure to the manifold inlet  15  proximate the back of the porcelain bowl of a flush toilet  10  is combined with the conduit  30  suppling exhaust for a separate vent  55  in the same room it is further recommended that the remotely located blower  20  create the negative pressure differential required of both. 
     A rotary vane alternating current (AC) ‘squirrel cage’ type blower is considered appropriate for the blower housing  12  depicted in  FIG. 4  but any type of blower  20  can be utilized in preferred embodiment of the principles relating to the present invention. A blower housing  12 , in fact, is not strictly necessary to fulfillment of said principles as a sufficiently diminutive blower can be located within the conduit  30 . An integrated circuit controlled rotating field direct current axial flow blower of the type commonly used for cooling personal computers can easily be disposed in line with the conduit  30  for example and more than one such blower  20  can be utilized in the same line if desired for purposes of providing sufficient negative pressure at the manifold inlet  15 . 
     If there is conduit  30  down stream from the exhaust port  21  or a very long length of conduit  30  between the manifold outlet  19  and the exhaust port  21  or a large number of bends, particularly 90°, in the conduit  30  it is suggested that more than one in-line blower  20  be utilized and specifically suggested that a pair of counter rotational blowers  20  be closely, about the diameter of the vanes, spaced apart from each other to maximize the air flow sustained and minimize back pressure hindering the same. 
     The use of a blower housing  12 , however, and a conventional AC blower  20  obviates these concerns and facilitates the supply of negative pressure relative to ambient pressure, i.e. less than 14.69 psia or 0 psig; to the manifold inlets  15  of a plurality of manifolds  11  each connected by a separate line of conduit  30  to the blower housing  12  as represented schematically in  FIG. 1 . A number of flush toilets  10  are economically serviced in this manner. It is, of course, sufficient with regard to the present invention to service only one flush toilet  10  regardless of the use of a blower housing  12 . 
     The manifold inlet  15 , as mentioned before, must be sufficiently shallow to fit between the top substantially flat surface of the porcelain bowl of an ordinary flush toilet  10  and the bottom flat surface of the seat hinged thereto. The distance between these two surfaces is typically a little more than, but can be as little as, one half of an inch (0.500″) and it is hence suggested that the total height of the manifold inlet  15  be restricted to this measure. The suggested diameter of the conduit  30  connected to the manifold  11 , inclusive of rigid pipe or duct or flexible hose, is larger than this and hence it is suggested that the manifold outlet  19  possess an effective diameter substantially greater in dimension than the height of the manifold inlet  15 . 
     The manifold  11  specifically depicted in  FIG. 2 , taken directly from engineering prints for prototypical manufacture, has a manifold inlet  15  three and three eighths inches (3.375″) wide and three eights of an inch (0.375″) high. This respectively includes four and two walls all approximately one sixteenth of an inch (0.0625″) thick. The resulting air passage is hence [3.375″−(4)(0.0625″)]×[0.375−(2)(0.0625″)]=[3.125″]×[0.250″]=0.78125 in 2 . The manifold outlet  19  has an ID of 1.319″ and a passage of π(r) 2 =π(ID/2) 2 =π(0.6595″) 2 =3.1415962(0.6595) 2 =1.3664 in 2 . The manifold outlet  19  hence possesses a passage that is 1.3664 in 2 /0.78125 in 2 =1.75 times greater than that possessed by the manifold inlet  15 . 
     Physics dictates that the air flow through each be the same, as the manifold  11  has no other openings, and hence the velocity of the air flow through the manifold inlet  15  is 1.75 times greater than that through the manifold outlet  19 . A manifold plenum  35  with a rounded top is located behind the manifold inlet  15 , connecting it to a laterally located manifold extension  39  having the annular cross section manifold outlet  19  at its termination. This rounded top facilitates laminar flow from the necessarily shallow and wide manifold inlet  15  to the preferably annular manifold outlet  19 . Laminar flow is preferred over turbulent flow in being more efficient, quieter, and more effective in removal of odors. 
     A sensor port  52  is preferably provided, as seen in  FIG. 6 , through the underside or bottom surface of the manifold extension  39  for insertion of an airflow probe to provide the velocity of the air flow and hence, with the cross sectional area of the manifold extension  39  known, the volume rate of air flow is readily yielded. This is considered a significant and valuable feature as it provides empirical, objective, verification that a system in accordance with the principles relating to the present invention has been properly installed and is functioning properly. Assistance during installation in sizing the blower  20  is considered to be the most significant direct benefit of this. 
     The hood  13  depicted in  FIG. 3  is considered vital to both proper installation and operation of a toilet ventilation system in accordance with the principles relating to the present invention. As mentioned earlier, the porcelain bowls of typical, modern, flush toilets  10  in the U.S. vary dimensionally. Every dimension varies except the standard spacing between the mounting bolts for the hinged seat and, typically, lid. The width and, most importantly, the length: from fore to aft; of the porcelain bowl varies. The width of the manifold inlet  15  is restricted by the distance between the two mounting bolts. The height of the same is restricted by the space between the top surface of the porcelain bowl and the bottom surface of the seat hinged thereto. 
     The position of the manifold inlet  15  with respect to the porcelain bowl is determined by the difference between the actual and the minimum distance between the cavity of the porcelain bowl and the back of the exterior of the same because the manifold plenum  35  necessarily extends below the top surface of the porcelain bowl behind the same and the front of the manifold  11 : the manifold inlet  15  cannot extend beyond the rear edge of the porcelain bowl cavity on the smallest model. The effectiveness of the negative pressure differential or suction supplied by the remote blower  20  through the conduit  30  to the manifold inlet  15  in removing noxious odors resulting from defecation, primarily, into the flush toilet  10  depends upon proximity of the manifold inlet  15  with the source of the odor. 
     For this reason a hood  13  is supplied with a curved fore edge  32  to the medial section  36  preferably possessing a curvature approximating that of the cavity of the porcelain bowl of the flush toilet  10 . The rear edge  33  of the medial section  36  of the hood  13  is straight as it overlaps the top surface of the manifold  11  between the two wings  16  each with a slot  17  for attachment to the mounting bolts for the hinged seat of the flush toilet  10 . The wings  16  of the hood  13  are long enough to ensure this overlap even on the largest length of porcelain bowl. On smaller bowls the wings  16  are trimmed off. 
     The open slots  17  of the wings  16  of the hood  13  are intended, as are the closed slots  17  in the wings  16  of the manifold  11 , to be engaged by the pair of uniformly spaced apart hinged seat mounting bolts on a standard flush toilet in the U.S. which, in installation, are loosened and then tightened after locating the exterior of the manifold plenum  35  against the rear of the porcelain bowl and the hood  13  such that the rear edge  33  of the medial section  36  overlaps the top of the manifold  11 , including the manifold inlet  15 , with the fore edge  32  of the hood  13  preferably overhanging the rear edge of the porcelain bowl cavity by the same distance as the height of the manifold inlet  15 , or about ⅜″ in the case depicted in the drawings attached hereto. 
     The portion of the wings  16  of the hood  13  extending rearward or aft of the mounting bolts is superfluous and is preferably trimmed away: i.e. removed by cutting, or, since the hood  13  is preferably made of plastic, snapped off with a flat rigid and hard object with a straight edge, such as a length of steel bar, first placed with an edge above the extent desired and the excess length of the two wings  16  pulled upward until separation is achieved. Assuming the hood  13  is made of thermoplastic, the preferred material, trimming the wings  16  can also be done with heat applied in a linear band across the desired trim line. 
     The heat can be supplied most easily by an electrical resistive element or a torch. It is not necessary to melt entirely through the intended part line. Once the substantially linear margin about the intended part line obtains a plastic state the excess portion of the wings  16  maybe moved upward, in a manner similar to that described directly above for snapping off the excess portion of the wings  16 , and elongation of the linear margin in a plastic state will readily enable the excess portions to be removed by simply pulling the same away. 
     A smooth edge is obtained in this manner, in contrast to either cutting with a saw or snapping the excess wing  16  portions off as described directly above, and heat may also be applied after removal of the excess wing  16  portions by cutting or snapping to obtain a smooth edge. Alternatively, the sharp or rough edges obtained by cutting or snapping may be abraded smooth using a sanding block, sand paper, file, emery board, et cetera. 
     Injection molding of both the hood  13  and the manifold  11  in thermoplastic is the most preferred manner of manufacture of these components. While blow, i.e. vacuum, molding of the hood  13  is also attractive the precision obtainable with injection molding is not readily achievable by blow molding. Construction of either component can also be achieved by welding together sub-components. The medial section  36  of the hood  13  depicted in  FIG. 3  is readily manufactured from molded thermoplastic sheet and welded to wings  16  either molded or cut from flat sheet. But integral construction is preferred. 
     Similarly, the manifold  11  depicted in  FIG. 2  is readily welded or glued together from sub-components. The flat top including the two wings  16  each possessing one slot  17  can be molded or cut from flat sheet and attached to a injection or blow molded body for the manifold plenum  35  with the manifold extension  39  comprising a third sub-component attached to the body. The two vertical vanes  57  seen in  FIG. 2  to divide the manifold inlet  15  into three air passageways can also comprise sub-components molded, cut, or cast from or into flat sheet and then attached to the manifold  11  in assembly. These vanes  57  are not necessary to fulfillment of the principles relating to the present invention but are useful in ensuring laminar air flow through the manifold inlet  15 . 
     It is considered that while the blower  20  is a purchased component the size of the same must be in accordance with the system as installed and this depends upon the number of manifolds  11 , the length of the conduit  30 , the number of right angles in the conduit  30 , and the size of the conduit  30 , i.e. the total load, that this is expected to vary considerably and, further, that the size requirement of the blower  20  is not readily calculated. The sensor port  52  is provided primarily for assistance in installation. It can be used to size the blower  20  but, preferably, is used in conjunction with a regulator  70  preferably provided on the back of the blower housing  12  as seen in  FIG. 8 . 
     The purpose of the regulator  70  is primarily to allow use of a single size blower for most residential installations in which a maximum of three manifolds  11  are contemplated, a maximum load is known, and a standard, maximum load sized, blower  20  can be provided. In the case of maximum load the regulator  70  will be closed and otherwise it can be opened to compensate for lesser loads. Readings of volume air flow through a manifold  11  using a sensor port  53  provide empirical data for regulation of the compensation provided by the regulator  70 . Opening the same reduces the pressure differential, and hence the measured air flow through, all the manifolds  11  in a system in accordance with the principles relating to the present invention. 
     The particular regulator  70  depicted in  FIG. 8  is comprised simply of a sliding door  72  held in place by two spaced apart horizontal flanges  27  displaceable manually by means of a handle  73  in typically, as shown, partial closure of the orifice  71  preferably disposed, as depicted, on the back end of the blower housing  12 , opposite the exhaust outlet  21 . It is emphasized that any other configuration will suffice, that a round plate used as a door  72 , for example, rotated to close and open the orifice  71  might be even simpler to implement and that multiple orifices  71  can be used as well. 
       FIG. 9  depicts use of a rectangular exhaust port  21  and disposition of a single relay  66  on the side of the blower housing  12  opposed to the inlet ports  22 . None of this is necessary. It is simply suggested for the sake of convenience. A rectangular exhaust port  21  more readily conforms to the exhaust configuration of a typical blower and while it is preferred in installation to exhaust through 3″ round metal duct an adapter  53  with one rectangular end and one round end will readily attach to the sleeve  23  of the rectangular exhaust port  21  depicted in  FIG. 9  and facilitate attachment of 3″ round metal conduit  30  in a manner similar to that depicted in  FIG. 7 . The adapter  53  depicted therein is intended to adapt 1.5″ PVC conduit  30  to 3″ round metal conduit  30  and it is suggested that it be made of PVC or another plastic. It is noted that the larger conduit  30  is seen to be fitted exteriorly to the adapter  53  while the smaller conduit  30  is inserted into the opposed end of the same and, as previously mentioned, is preferably threaded therein. An adapter  53  for a rectangular exhaust port  21  is preferably made of sheet metal and it is largely irrelevant as to whether the ends of the adapter  53  fit interiorly or exteriorly to the sleeve  23  about the exhaust port  21  or the end of the conduit  30  so connected. 
     It is emphasized that the foregoing is intended to provide one practiced in the art with the best known manner of making and using a system in preferred accordance with the principles relating to the present invention and the same is not to be construed in any manner as being restrictive of said principles nor of the rights and privileges obtained by Letters Patent for which