Patent Publication Number: US-6698225-B2

Title: Biased condensation trap

Description:
This application claims benefit of Provisional No. 60/314,279 filed Aug. 22, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to removing condensate from air conditioning systems as well as other systems or devices that collect condensation. 
     Air conditioning systems generally include a blower which blows or draws air over a heat exchanger coil on which condensation accumulates and drips to a discharge pan positioned below the coil. The condensation (or condensate) which overflows from the pan is drained from the system through a discharge port on to the ground or into the sewer system. 
     Referring to FIG. 1A, an air conditioning system  10  includes a blower  11  positioned to draw external air through a filter  14  and push the air over a heat exchanger  12 , thereby presenting positive pressure at the discharge port where the condensate is discharged. A system having the blower positioned with respect to the heat exchanger in this manner is known as a “blow-through” system. Condensate from the heat exchanger drips into a condensate pan  13  having a drain port  15  connected to a U-shaped condensate trap  16 . 
     Referring to FIG. 1B, on the other hand, if the blower is positioned to draw air over the coil, the system is a “draw-through” system with a negative pressure present at the port where the condensate is discharged. With this arrangement, blower  11  is positioned to pull air through the heat exchanger. 
     A condensate trap  16  in the form of U-shaped piping is generally provided at the discharge port. In a draw-through type system, the U-shaped trap  16  must be filled with water prior to starting up the system. In this case, the water serves as a barrier and is necessary in preventing the condensate pan from overflowing when the system is initially started up. In a blow-through type system, there is no requirement for “priming” the system because condensation will accumulate during operation. In either case, the water in the trap forms a barrier between atmospheric pressure at the discharge port of the trap and the pressure level within the system, thereby preventing escape of conditioned air in the system of FIG. 1A or introducing air into the system of FIG.  1 B. The trap also collects foreign material (e.g., sediment) passed through the discharge pan from the system. This foreign material can collect in the bottom of the trap and clog the system. 
     SUMMARY OF THE INVENTION 
     The invention is related to a condensate trap for use with an air conditioning system allowing trapped condensate and foreign material collected in the trap to be safely removed from the system. 
     In a general aspect of the invention, the condensate trap for an air conditioning system includes a chamber having an upstream port for coupling to the air conditioning system and a downstream port open to the external atmosphere, a sealing device disposed in the chamber, an upper seat member disposed between the sealing device and upstream port, and a lower seat member whose upper surface is adapted to receive a biasing member which is disposed between the sealing device and the lower seat member. The biasing member maintains the sealing device in biased contact with the upper seat member to prevent the egress or ingress of air from or into the air conditioning system. Moreover, in response to a predetermined amount of condensation fluid accumulating in the chamber, the sealing device moves out of contact with the upper seat member to allow the fluid to drain from the downstream port of the chamber. 
     Embodiments of this aspect of the invention may include one or more of the following features. The biasing member is a spring, or a tube or rod made from rubber or other resilient material. The sealing device is a float, for example, a round and hollow ball. The chamber is formed as a cylindrical pipe. The upper seat member includes a gasket seated in upper seat member. The lower seat member also includes a gasket seated in lower seat member, the gasket having an upper surface adapted to support the biasing member. The cylindrical pipe is formed of a transparent material to allow the installation or service technician to visually inspect and ensure that the condensate trap is properly operating. 
     Among other advantages of the invention, infiltration of air into and out of the system is minimized, thereby reducing pressure imbalances within the building. Preventing transfer of air between the air conditioning system and external atmosphere is achieved by the trap whether the system is used with a draw-through or blow-through system. For example, when used with a draw-through system, the trap prevents air from the external atmosphere (which may be polluted) from infiltrating the system. When used with a blow-through system, the trap prevents loss of air from the air conditioning system to the external atmosphere. In either case, the trap also prevents collected condensate or other foreign matter (e.g., sediment) from accumulating in the trap. The trap is configured to allow the condensate and foreign matter to drain from the system through the bottom of the trap. Thus, unlike conventional U-traps, sediment which can clog the trap does not accumulate in the trap. Moreover, the trap isolates the air conditioning system from the external atmosphere, without requiring the use of fluid (e.g., collected condensate) which is required in conventional U-piping traps. Thus, in the present invention, there is no risk of damaging the trap due to freezing of the fluid in the trap. 
     The condensate trap is compact, easy to install, and is easily removed from the system for maintenance or repair. The trap can be installed at virtually any point along the length of the drain pipe. For example, the trap can be installed at the end of an outdoor drain pipe and should be accessible for cleaning. In humid environments (e.g., regions of the southern United States) certain types of algae can grow on and within the trap. In such environments, it may be advantageous to have the trap outside where ultraviolet light will help prevent the growth of algae. The trap can also be directly substituted for a conventional U-piping trap without requiring any modification to the existing air conditioning or duct system. The spring is made from a non-corrosive material, such as stainless steel, and the length or other dimension of the spring can be changed to match requirements of different systems. Other features and advantages directed to the construction and materials of the condensate trap  20  are discussed in U.S. Pat. No. 5,644,925, which is incorporated herein by reference. 
     Other features and advantages of the invention will become apparent from the following detailed description, and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a schematic representation of a conventional blow-through type system. 
     FIG. 1B is a schematic representation of a conventional draw-through type system. 
     FIG. 2 is a perspective, exploded view of the condensate trap in accordance with the invention. 
     FIG. 3A is a side view showing the condensate trap of FIG. 2 in use with a draw-through and a blow-through system where the weight of the water is not sufficient to deflect the sealing device. 
     FIG. 3B is a side view showing the condensate trap of FIG. 2 in use with a draw-through or a blow through system where the weight of the water is sufficient to deflect the sealing device. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 2, a condensate trap  20  which may be substituted for the U-shaped traps  16  shown in FIGS. 1A and 1B is shown. Condensate trap  20  includes a transparent cylindrical tube  22  having a length of approximately two inches (drawing not to scale) and an inner diameter of 1 ½ inches. Tube  22  is formed of PVC plastic and includes threads  24 A at its ends for receiving corresponding threads  24 B of adapting fixtures  26 ,  28 . Adapting fixtures are used to connect tube  22  to the rest of the air conditioning system and the discharge piping, respectively. In particular, fixtures  26 ,  28  include inlet and outlet ports  26   a,    28   a,  respectively (see FIG.  3 A), which extend about the axis of the tube. Fixtures  26 ,  28  are rotatable about the axis of the tube to facilitate connecting it to the piping of the air conditioning system and discharge piping. It is important that condensate trap  20  must be mounted in a substantially vertical position. 
     In other embodiments, tube  22  and fixtures  26 ,  28  are threadless. In these embodiments, a pair of threaded fasteners (not shown) are used to clip a pair of surfaces extending outwardly (not shown) from fixture  28  and are received through holes defined by fixture  26 . 
     A round hollow float  30  (e.g., a ping pong ball) having a diameter slightly less than the diameter of the tube is positioned in tube  22  and is kept in biased contact by a biasing member  50  (e.g., a spring) with a gasket  42  which is formed of rubber and is seated within the upper adapting fixture  26 . Float  30  can be formed of a variety of materials including plastic and lightweight metal. A gasket  36 , also formed of rubber, is placed in lower adapting fixture  28  and has an upper surface adapted to receive biasing member  50 . Biasing member  50  is preferably formed of a non-corrosive material such as stainless steel, rubber, or plastic and under normal operating conditions biases float  30  against gasket  42  thus preventing the ingress or egress of air into or out of the air conditioning system. 
     Referring to FIGS. 3A and 3B, in a draw-through system, when the blower is activated, a negative pressure within the tube relative to the external atmosphere exists. Condensate  35  draining into the chamber from the condensate pan accumulates on top of float  30  until the weight of the condensate overcomes the negative pressure exerted on the float by the air conditioning system and the force exerted on float  30  by biasing member  50 ; thus allowing the condensate to drain around the float and to outlet port  28   a  of the trap (see FIG.  3 B). With the weight of the condensate removed, float  30  is pushed back into position against gasket  42  by biasing member  50  and the negative pressure (see FIG.  3 A). 
     Similarly, in a blow-through system, when the blower is activated, a positive pressure exists within the tube relative to the external atmosphere. The positive pressure tends to push float  30  toward lower adapting fixture  28 . The force exerted by biasing member  50  against float  30  is such that float  30  maintains contact with gasket  42 . Condensate  35  drains into tube  22  and accumulates on top of float  30  until the weight of the condensate plus the positive pressure overcomes the force of the spring exerted on float  30  and the condensate drains to outlet port  28   a  of the trap (see FIG.  3 B). With the weight of the condensate removed, float  30  is pushed back into position against gasket  42  by biasing member  50  (see FIG.  3 A). 
     Thus, isolation between the air conditioning system and external atmosphere is maintained at all times whether the condensate trap is used with a draw-through or blow-through system even during periods in which the system is not operated. 
     Other embodiments are within the scope of the claims. For example, the float, chamber, seals and ports may be any of a variety of materials (e.g., plastics, metals, glass, rubber) and shapes. Furthermore, it is important to appreciate that the invention is not limited to air conditioning systems but is applicable to any system or device that collects condensation.