Patent Publication Number: US-2002000093-A1

Title: Air conditioner condensation pan overflow protection

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application is entitled to the benefit of Provisional Patent Application Ser. #60/214443, 2000 Jun. 28.  
       BACKGROUND—FIELD OF INVENTION  
       [0002] This invention relates to refrigeration air conditioner condensation pans, specifically to a method of preventing the overflow of such pans and the subsequent damage caused by such overflow.  
       BACKGROUND—DESCRIPTION OF PRIOR ART  
       [0003] Refrigeration air conditioners for homes usually have the cooling coils mounted in the attic. During the cooling process, water is condensed from the air, is caught in one or more condensation pans mounted below the cooling coils, and must be removed by drains in the pan or pans. These drains often plug up, and the water in the pans overflows and causes structural and property damage to the house. This is a common occurrence. It has happened to us twice, and to many of our friends and neighbors.  
       SUMMARY  
       [0004] In accordance with the present invention, a liquid level sensor and associated electronics are attached to an air conditioner condensation pan or pans, to prevent overflow by shutting off the air conditioner fan and compressor, and optionally sounding an alarm.  
       OBJECTS AND ADVANTAGES  
       [0005] Accordingly, several objects and advantages of my invention are:  
       [0006] (a) to prevent the air conditioner condensation pan overflow and subsequent damage to houseand property by shutting off the fan and compressor;  
       [0007] (b) to prevent the air conditioner from being restarted until the pan drain(s) is/are cleared of obstruction and the pan(s) drain properly. 
     
    
    
     DRAWING FIGURES  
     [0008]FIG. 1 is a schematic drawing of the condensation pan(s) associated with the cooling coils of a refrigeration air conditioner, and the drains to such pans.  
     [0009]FIG. 2 is a schematic of the electrical wiring associated with the refrigeration air conditioner.  
     [0010]FIG. 3 shows an installation of a liquid level sensor in one condensation pan of a refrigeration air conditioner.  
     [0011]FIG. 4 shows one embodiment of the electronic circuitry required to shut off the air conditioner fan and compressor.  
     [0012]FIG. 5 shows an alternative embodiment of the electronic circuitry, incorporating an alarm circuit.  
     REFERENCE NUMERALS IN DRAWINGS  
     [0013] 10  cooling coils  
     [0014] 15  refrigerant lines  
     [0015] 20  fan  
     [0016] 25  electrical lines from thermostat to fan  
     [0017] 30  ductwork  
     [0018] 40  primary condensation pan  
     [0019] 45  primary condensation pan drain  
     [0020] 50  secondary condensation pan  
     [0021] 55  secondary condensation pan drain  
     [0022] 60  electrical lines from thermostat, fan, compressor  
     [0023] 70  thermostat  
     [0024] 80  compressor  
     [0025] 90  electrical lines from thermostat to compressor  
     [0026] 95  alternative condensation pan drain  
     [0027] 100  liquid level sensor  
     [0028] 105  wiring from liquid level sensor to sensor power supply and trigger  
     [0029] 110  sensor power supply and trigger  
     [0030] 120  circuit breaker  
     [0031] 130  alarm 
    
    
     DESCRIPTION—FIGS.  1 ,  2  and  3 —PREFERRED EMBODIMENT  
     [0032] A standard home refrigeration attic installation is shown in FIG. 1. A compressor sends refrigeration fluid through refrigerant lines  15  to a set of cooling coils  10  mounted in ductwork  30  in an attic. The cooling coils have moist air blown across them by a fan  20  controlled by a thermostat  70  through wiring  25 , and into the ductwork  30 . The condensed moisture from the air falls into one or more condensation pans  40 ,  50  and is drained into the house sewer or out of the house at the roofline through drains  45 ,  55 . In some home installations, only one pan  40 , called the primary pan, is used, while other installations use two pans  40 ,  50 , a primary and a secondary pan. The secondary pan is below the primary pan, and larger, in order to catch any spillage from the primary pan.  
     [0033]FIG. 2 shows the standard electrical wiring associated with a refrigeration air conditioner. A thermostat  70  in the house senses the air temperature, and turns the compressor  80  and the fan  20  on or off as required. Power for the thermostat, fan and compressor is furnished from the house power lines  60 . The thermostat  70  switches the compressor  80  and the fan  20  on and off through different circuits  90 ,  25 .  
     [0034] A preferred embodiment of the present invention is shown in FIG. 3. A liquid level sensor  100  is attached to the inside of each existing condensation pan  45 ,  55 . The liquid level sensor has its associated electronics  110  consisting of a power supply and a triggering mechanism connected to a circuit breaker  120  in the main leg of the power line leading to the compressor  80  and the fan  20 . The circuit breaker  120  remains closed until the liquid level sensor  100  senses that water is about to spill from one or both pans. At that point, the triggering electronics  110  will open the circuit breaker  120 , preventing power from getting to the compressor  80  and the fan  20 . The circuit breaker  120  will remain open until the condensation pan drain(s) is/are cleared, the water level returns to a normal state, and the circuit breaker is reset manually. Any attempt to reset the circuit breaker while the pans are still close to spilling will cause the circuit breaker to open again. Such a circuit is shown in FIG. 4.  
     [0035] In the preferred embodiment, the liquid level sensor can be an optoSchmitt sensor such as the LL series manufactured by Honeywell. However, the sensor and its associated electronics can be any type of liquid level sensor such as those described in various engineering manuals. Many types of physical effects can be used to determine liquid level: pressure, mechanical, conductive, capacitive, photoelectric, heat-sensing, ultrasonic, nuclear, microwave, and damped-oscillation effects have all been used as liquid-level sensors. A good reference is “Handbook of Transducers,” by Harry N. Norton, Prentice-Hall, Englewood Cliffs, N.J., 1989.  
     ADDITIONAL EMBODIMENT  
     [0036] An addition of an alarm  140  to the liquid level sensor circuit can alert the homeowner or a neighbor to a potentially damaging situation. Such a circuit is shown in FIG. 5.  
     ADDITIONAL EMBODIMENT  
     [0037] An addition of a liquid level sensor, associated electronics, a circuit breaker and an alarm to “swamp” or evaporative air conditioner drain pans can prevent overflow and roof and home interior damage, since evaporative units are generally roof-mounted.  
     OPERATION OF INVENTION  
     [0038] A home refrigeration air conditioning unit works by compressing a refrigerant with a compressor  80  through cooling coils  10  mounted in ductwork  30 . A fan  20  circulates household air across the cooling coils  10  through and out of the ductwork  30 , into the interior of the house, and back into the ductwork  30 .  
     [0039] The cooling coils  10 , fan  20  and ductwork  30  are usually mounted in the attic of a house.  
     [0040] When the air is cooled by passing across the cooling coils  10 , water condenses out of the air and falls into one or more condensation pans  40 ,  50 . This water is drained to the house sewer plumbing, or to the outside of the house, via drains  45 ,  55  in the pans.  
     [0041] Some installations of refrigeration units have only one condensation pan, called the primary pan  40 . Other installations have two pans, called the primary pan  40  and the secondary pan  50 . The secondary pan  50  catches and drains any water spilling from the primary pan  40  due to malfunction of the primary pan drain  45 .  
     [0042] In some installations of the refrigeration units, the primary pan  40  is an integral part of the fan-cooling coil-ductwork assembly  10 ,  20 ,  30 .  
     [0043] Some installations of the condensation pans have the drains  45 ,  55  on the pan sides, and some installations have the drains  45 ,  55  on the pan bottoms.  
     [0044] If both the primary pan drain  45  and secondary pan drain  55  are stopped up, or otherwise unable to conduct water away at a sufficient rate from the pans, the pans will overflow into the attic, causing structural and property damage to the house. In hot, humid climates such as the Texas Gulf Coast, refrigeration units can condense as much as 6 gallons of water a day from the air during normal operation.  
     [0045] The present invention proposes adding a liquid level sensor  100  to each existing condensation pan  40 ,  50 , to prevent water overflow. The sensor  100  will determine when the liquid level in the pans  40 ,  50  is about to overflow the edge of the pans, and will shut off the electricity to the fan  20  and the compressor  80  through its power supply electronics and trigger circuit  110 .  
     [0046] The electricity is shut off by a circuit breaker  120  in one leg of the power lines to the compressor  80  and fan  20 . This circuit breaker is opened by the action of the trigger circuit  110  of the liquid level sensor. The compressor  80  and fan  20  cannot be restarted before the circuit breaker  120  is manually re-engaged. Since the liquid level sensor circuitry  110  is always attached to the power lines, any attempt to reset the circuit breaker  120  before the pans  40 ,  50  are drained will result in the circuit breaker  120  being opened again.  
     [0047] An addition of an alarm  130  to the liquid level sensor  100  and its electronics  110  will alert the homeowner, or neighbors or friends if the occupants of the house are not at home.  
     ADVANTAGES  
     [0048] From the description above, three advantages of my invention become apparent:  
     [0049] (a) the liquid level sensor and its circuitry shut off the compressor and fan, thus eliminating condensed water overflow from the condensation pans and subsequent damage to the home and its contents.  
     [0050] (b) the compressor and fan cannot be started again until the pan drain blockage(s) is/are cleared and the liquid level goes down below the sensor level.  
     [0051] {circle over (c)} installation of such a protective system to the drain pan of an evaporative air conditioner will also prevent overflow and subsequent damage.