Radon and other gas ventilator
BACKGROUND OF THE INVENTION 
     The present invention relates to vent devices which use existing ductwork for reducing the concentration of radon gas and similar undesirable gases in houses and apartments. 
     Heretofore kitchen, bathroom and other vent fans have been used to vent radon gas from buildings through existing ductwork. The disadvantage of these devices is that they do not act upon radon until after it has permeated the occupancy areas of the house and, therefore, is already a health threat. A device of this type is disclosed in U.S. Pat. No. 3,606,593 and in U.S. Pat. No. 4,681,024. Vents which connect to furnace chimneys must withstand the high temperatures of flue gas, require an experienced installer and may cause poisonous flue gases to leak into the building if not properly maintained. Such a device is disclosed in U.S. Pat. No. 4,543,941. 
     Additional devices are known in the art. In the known devices sealants are applied to cracks in the building foundation to prevent radon gas from entering. The disadvantage of the above devices is that the sealant is difficult to apply and requires removal of existing floor coverings. Sealants can not be applied in subfreezing temperatures. Sealants rely upon an air tight barrier which has been known to cause the undesirable side effect of increasing the concentrations of other, sometimes toxic, indoor fumes, gases and odors. 
     An additional known device aims to reduce the concentration of radon below the foundation and thus minimize any inflow to the building. These devices consist of a perforated vent pipe or duct installed beneath the foundation and extending beyond the building walls. Radon gas flows through the path of least resistance from the ground into the pipe and beyond the building walls where it dissipates harmlessly. 
     The disadvantage of the above device is that it is difficult to retrofit to existing structures. It relys upon the presence of a permeable sub-foundation such as gravel to reliably vent each area of the foundation. This device requires materials, preparation and installation in addition to that which is normally required for a new building as otherwise constructed. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a novel device for venting radon and other gases from houses, which avoids the disadvantages of the prior art and which is energy efficient. 
     One feature of the present invention resides, briefly stated, in a radon gas ventilator which utilizes existing ductwork and house wall ventilation openings, in the case of existing houses, and such ductwork and wall openings as would be otherwise provided in new houses. This is achieved with a ventilator which can be inserted in series into the duct which connects a conventional, heated, fan circulated laundry dryer to a house ventilation opening. 
     The ventilator duct body having a generally circular port for connecting to a laundry dryer vapor and lint exhaust port, one or more ports being provided for a device such as a fan to produce a differential pressure to exhaust airborne radon gas and radon progeny and a generally circular port through which the radon gas and alternately laundry dryer vapors admitted through the other ports can flow to the house wall ventilation opening provided for use with the laundry dryer. 
     A further object is to exhaust radon gas from a house before it has permeated the primary living quarters of the building. This can also be achieved by locating the ventilator in a laundry dryer vent duct which is normally located in a house basement or ground floor laundry room where radon gas concentrations are highest and where human contact is least. 
     Readers will find further objects and advantages of the invention from a consideration of the ensuing description and the accompanying drawings. 
    
    
     DRAWING 
     FIG. 1 is a perspective view of the radon ventilator installed in a laundry dryer vapors and lint exhaust duct. 
     FIG. 2 is an enlarged perspective of the radon ventilator with section line A--A. 
     FIG. 3 is a sectional view of the radon ventilator along section line A--A indicated in FIG. 2. 
    
    
     DRAWING DESCRIPTION 
     FIG. 1 shows a conventional laundry dryer 10 having a door 12 through which wet laundry and clothing is placed into a chamber (not shown). The dryer cabinet 14 contains the chamber, an electric or gas burning heat source and a fan for circulating heated air through the chamber to a vapor and lint exhaust port 16. Temperature control 15 and cycle timer 17 provide a wide range of dryer operation to effectively dry small or large laundry loads. 
     In a conventional home or apartment installation the laundry dryer vapor and lint exhaust port 16 is connected by circular ducts 31 to the house wall ventilation opening 32 which penetrates the wall to the outside atmosphere. In this way the dryer exhaust vapor and lint are transported out of the house to the outdoors. 
     In order to vent radon gas, radon progeny (radon decay products) and other objectionable gases from a house basement or laundry room my invention utilizes a three ported ventilator 20 having two generally circular ports 22a and 22b which are connected in series between two sections of the laundry dryer ducts 30 and 31 as shown in FIGS. 1 to 3. The ventilator vapor inlet port 22a is connected to the laundry dryer vapor and lint exhaust port 16 by way of the duct 30. The ventilator outlet port 22b is connected to the house wall ventilation opening 32 by way of duct 31. 
     The ducts 30 and 31 are held in place on the ventilator ports 22a and 22b by plastic or metal clamps 34 or by other fastening means. The ventilator body 22 is made of a rigid and heat resistant material such as thermoplastic, thermosetting plastic, sheet metal or other suitable material and it has a thin walled construction to form a hollow body having three ports in fluid communication. The third ventilator body port constitutes the radon inlet port 22c which is formed with its axis substantially perpendicular to the vapor inlet port 22a. 
     Mounted within the ventilator duct body 22, between the vapor inlet port 22a and the radon inlet port 22c, is a freely pivoting, substantially thin plate flow damper 24. The damper 24 pivots on its hinges 26 to meet and close the radon inlet port 22c from the remainder of the ventilator body. With the damper in this position there is formed within the ventilator duct body 22 a single, unobstructed flow path from the vapor inlet port 22a to the outlet port 22b. 
     The ventilator duct body 22 is configured so that the junction of the vapor inlet port 22a at the duct body 22 is substantially planar. This substantially planar junction forms a seating surface for the pivoting damper 24 to fit flush against and to close, thereby preventing fluid communication between the vapor inlet port 22a and the remainder of the ventilator duct body 22. 
     In this position the damper together with the ventilator duct body 22 form a flow path from the radon inlet port 22c to the outlet port 22b. 
     For the damper 24 to alternately seal either the vapor inlet port 22a or the radon inlet port 22c it must be positioned so that the damper 24 independently contacts the interior seating surface of each port. 
     A radon exhaust fan assembly including a frame and mount 28a, fan blade 28b, fan motor 28c and grille 27 is mounted to the ventilator duct body 22 at the exterior of the radon inlet port 22c. 
     In operation the radon exhaust fan forces radon laden room air past the grille 27 against the freely pivoting damper 24 with sufficient momentum to cause it to pivot away from the radon inlet port 22c and to seat against the interior surfaces of the vapor inlet port 22a. A radon exhaust passage is thereby formed through the ventilator 20 into the duct 31 and outdoors through the wall ventilation opening 32. Backflow of the exhaust radon through duct 30, into the dryer 10 and back into the room is prevented by the seating action of the damper 24 against the interior surface of the vapor inlet port 22a. 
     When the laundry dryer is on, the momentum of the dryer vapors and lint exhaust forces the damper 24 away from the vapors inlet port 22a and to seat against the interior surfaces of the radon inlet port 22c. An unobstructed vapors and lint passage is thereby formed through the ventilator 20 into the duct 31 and outdoors through the wall ventilation opening 32. 
     Details of a second embodiment of the invention are shown in FIG. 3. The radon laden air exhausted from the basement or laundry room by the radon ventilator is normally replaced by air which flows from the outdoors through makeup air ducts generally found in houses and around doors, windows and through bathroom vents. In houses which are very air tight a separate air replenishment tube 38 provides a path from the outside atmosphere through the wall ventilation opening 32, through the duct connecting the ventilator outlet port 22b to the wall ventilator opening 32 and through the ventilator body at the hole 36 which is located so that the tube 38 does not impede the movement of the freely pivoting damper 24. The tube 38 extends a distance from the wall ventilator opening 32 along the exterior of the house so as not to re-entrain the radon exhausted from the house. The tube extends through ventilator body hole 36 a distance away from the ventilator so that replenishment air drawn into the house from the outdoor atmosphere is not immediately vented back through the radon exhaust fan. 
     In operation, whenever the radon exhaust fan or the laundry dryer exhaust forms a draft, atmospheric outdoors air flows through the air replenishment tube 38 into the house to equalize pressure within and without the house. 
     A simple modification of this embodiment forms a new, third embodiment wherein a portion of the air replenishment tube 38 is made of a heat conductive material which forms a heat transfer surface between the radon laden exhaust air and the replenishment air. In operation, exhausted radon laden air transfers heat to the counterflowing, replenishment air present within the air replenishment tube 38 flowing into the house from the outdoors. 
     Thus the reader will see that the present invention provides an improved method to limit exposure to radon and other harmful airborne gases. The deleterious effects of such exposure are thus avoided or reduced. 
     While my above description contains may specificities, these should not be construed as limitations on the scope of the invention, but rather, as an exemplification of several preferred embodiments of these. Many other variations are possible. For example, the three ports of the ventilator body need not be arranged with the radon inlet port perpendicular to either of the remaining two ports.