System for fluid pump down using valves

A valve system includes a motor, a first valve, a second valve, and a controller. The first valve is connected to the motor shaft and is rotatable to an open position, in which fluid flows through a first channel, and a close position, in which fluid is prevented from flowing through the first channel. The second valve is connected to the motor shaft and is rotatable to an open position, in which fluid flows through a second channel from a first end to a second end, and to a close position, in which fluid is prevented from flowing through the second channel. The controller is connected to the motor and can sequentially actuate the first valve and the second valve to create at least a first, second, third, and fourth position.

FIELD

The field of the disclosure relates generally to fluid pump down using valves and, more particularly, to valve systems for removing refrigerant used in cooling systems from the interior of a structure.

BACKGROUND

Known heating, ventilation, and cooling (HVAC) systems and other cooling systems use refrigerants to remove heat from the conditioned space. In these systems, refrigerant flows from an outdoor condensing unit through a liquid line into an interior space, such as a residence. The liquid refrigerant boils while absorbing heat to be removed from the conditioned space, thereby cooling blowing air before the refrigerant is returned to a compressor in the outdoor condensing unit using a suction line. Many of these known HVAC systems use chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and/or hydrofluorocarbons (HFCs) and other similar, relatively inert compounds as refrigerants. Advantageously, such refrigerants are non-flammable, meaning that the refrigerants are relatively safe while they are pumped through residences and other facilities. As such, between cycles of the HVAC system, residual refrigerant may be left in interior portions of the HVAC system and pose little risk to the structure. Typically, these systems include manually operated service valves, which facilitate shipping and service of the system by isolating the condensing unit from the home side of the system when closed. Additionally, such systems using non-flammable refrigerants can be easily serviced using common Schrader valves or other similar valves to monitor pressure and add or remove the refrigerants from the system.

However, CFCs, HCFCs, HFCs and other similar compounds have a high Global Warming Potential (“GWP”) or Ozone Depletion Potential (“ODP”) and, as such, pose an environmental risk. Because of this high GWP potential, there has been a drive to use refrigerants having a lower GWP. Unfortunately, many such potential lower GWP refrigerants, such as difluoromethane, are flammable. In fact, many of the proposed low GWP refrigerants carry an American Society of Heating, Refrigerating and Air-Conditioning Engineers (“ASHRAE”) designation of A2L, which indicates they are mildly flammable. Other low GWP refrigerants with higher flammability, carrying designations of A2 and A3, are also potential replacements for high GWP refrigerants. The flammability of these refrigerants poses a potential risk to the interior space if a quantity of A2L-designated or other flammable refrigerant above a critical volume is left within the interior space between cooling cycles of the HVAC system. For example, under some proposed U.S. regulations, a volume of A2L-designated refrigerant above 4 pounds (approximately 450 grams) within the interior space is considered dangerous to an average residential structure and requires additional mitigation to isolate the refrigerant from the environment as compared to non-flammable refrigerants.

BRIEF SUMMARY

In one aspect, a valve system includes a motor, a first valve, a second valve, and a controller. The motor has a shaft. The first valve is connected to the shaft and is rotatable to an open position, through which fluid flows to a first channel, and a close position, in which fluid is prevented from flowing through the first channel. The second valve is connected to the shaft and is rotatable to an open position, through which fluid flows to a second channel, and to a close position, in which fluid is prevented from flowing through the second channel. The controller is connected to the motor and is configured to, using the motor and the shaft, sequentially actuate the first valve and the second valve to create at least a first, second, third, and fourth position. In the first position, the first valve is in the closed position and the second valve is in the closed position. In the second position, the first valve is in the open position. In the third position, the first valve is in the open position and the second valve is in the open position. In the fourth position, the first valve is in a closed position and the second valve is in the open position.

In another aspect, a cooling system includes an air handling unit, a condensing unit, a suction line, a liquid line, and a valve system. The air handling unit is configured to distribute air and includes an evaporator. The condensing unit includes compressor and a condenser. The compressor is fluidly connected to the condenser by a condenser line configured to channel refrigerant from the compressor to the condenser. The suction line is configured to channel refrigerant from the evaporator to the compressor. The liquid line is configured to channel refrigerant from the condenser to the evaporator. The valve system includes a motor, a liquid-line valve, a suction-line valve, and a controller. The motor has a shaft. The liquid-line valve is connected to the shaft and is in fluid communication with the liquid line. The liquid-line valve includes a liquid-line channel therethrough and the liquid-line valve is rotatable to an open position, in which refrigerant flows through the liquid-line channel, and to a closed position, in which refrigerant is prevented from flowing through the liquid-line channel. The suction-line valve is connected to the shaft and is in fluid communication with the suction line. The suction-line valve includes a suction-line channel therethrough and the suction-line valve rotatable to an open position, in which refrigerant flows, using suction, through the suction-line channel, and to a close position, in which refrigerant is prevented from flowing through the suction-line channel. The controller is connected to the motor and is configured to, using the motor and the shaft, sequentially actuate the liquid-line valve and the suction-line valve to create at least a first, second, third, and fourth position. In the first position, the liquid-line valve is in the closed position and the suction-line valve is in the closed position. In the second position, the liquid-line valve is in the open position. In the third position, the liquid-line valve is in the open position and the suction-line valve is in the open position. In the fourth position, the liquid-line valve is in a closed position and the suction-line valve is in the open position.

Corresponding reference characters indicate corresponding parts throughout the drawings. Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.

DETAILED DESCRIPTION

The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to cooling systems in which refrigerant is pumped between exterior and interior spaces, including industrial, commercial, and residential applications.

FIG. 1is a block diagram of a heating, ventilation, and air conditioning (HVAC) system100for a structure102in accordance with an example embodiment of the present disclosure. In this example, a forced air system104is shown, though other systems are contemplated. Forced air system104includes a main control module108, a blower114, an air chamber116, an expansion device188, and an evaporator192including evaporator coils194. Blower114is controlled by main control module108. Main control module108includes one or more processors119and one or more memory devices121. A thermostat122includes one or more processors131and one or more memory devices133. Main control module108receives control signals127from thermostat122. Thermostat122may include one or more temperature set points specified by a user through a user interface129, which may be mounted on thermostat122or may be embodied in a mobile device, such as, but not limited to a smartphone.

In operation, return air106is pulled from structure102by blower114into plenum116. Thermostat122may direct that blower114be turned on at all times or only when a cooling or heating request is present. Evaporator192is located within plenum116above blower114. Evaporator192is placed in series with blown air107from blower114so that when cooling is desired, evaporator removes heat from blown air107, thereby generating a cool supply air132. It will be appreciated that HVAC system100may include heating components as well, such as a burner (not shown).

In an example, a split-type air conditioning system is shown including a condensing unit178located in an area101outside of structure102. Condensing unit178includes a compressor180, a fan182, a condenser184, and a condensing unit control module196. Condensing unit control module199is operatively coupled to main control module108and is configured to control the operation of compressor180and fan182. Compressor180is fluidly connected to evaporator192by means of a suction line138. Compressor180is also fluidly connected to condenser184by means of a compressor discharge line140. Condenser184is connected to evaporator192by means of liquid line142. Expansion device188is coupled along liquid line142between condenser184and evaporator192. Each of the suction line138, compressor discharge line140, and liquid line142are in fluid communication with one another such that refrigerant136cycles through each line138,140,142during a single cooling cycle of HVAC system100.

Refrigerant136may be, for example, traditional, nonflammable HVAC refrigerants such as, for example, CFCs, HCFCs, HFCs, and the like. In alternative embodiments, refrigerant136may be mildly flammable, such as, for example, refrigerants with an ASHRAE designation of A2L, like difluoromethane and 1,3,3,3-tetrafluoropropene. In further embodiments, refrigerant136is any refrigerant that can be used with HVAC system100as described herein.

In an example operation of HVAC system100, during the cooling of blown air107, evaporator192is filled a low pressure, low temperature refrigerant136in the liquid form. As blown air107passes across the coils of evaporator192, blown air107is cooled and refrigerant136within the coils is heated, generating a refrigerant136having a low temperature and low pressure in gas form. Refrigerant136is then drawn from evaporator192to compressor180within condensing unit178using suction line138. During this process, refrigerant136is drawn from inside structure102to outside area101. Compressor180rapidly compresses refrigerant136, generating a high temperature, high pressure refrigerant136. High temperature, high pressure refrigerant136in gas form is channeled through compressor discharge line140into condenser184, where refrigerant136is channeled through a series of condenser coils181. As refrigerant136travels through condenser coils181, outside air183is drawn through the outside of the condenser coils181using fan182, which cools and condenses the refrigerant136. The medium temperature, high pressure liquid refrigerant136is then channeled through liquid line142back into structure102and to expansion device188, causing refrigerant136to expand entering the evaporator192and lowering both the temperature and pressure of the liquid refrigerant136. This low temperature, low pressure liquid refrigerant136is then channeled through evaporator to begin the air cooling process again. The above example operation of the cooling system of HVAC system100is described for illustrative purposes, but the phases of the refrigerant and the operation conditions of HVAC system100can vary according to a number of factors, such as the type of refrigerant used.

In this example, at least a portion of suction line138has a larger diameter than liquid line142. More specifically, in an embodiment, suction line138is about ¾ inch to about 1 inch in diameter and liquid line142is about ¼ inch to about ½ inch in diameter. In further embodiments, suction line138us about ⅞ inch in diameter and liquid line142is about ⅜ inch in diameter.

HVAC system100includes a suction-line valve202located along suction line138between evaporator192and compressor180. Suction-line valve202is configured to control the flow of refrigerant through suction line138and into compressor180. In an embodiment, suction-line valve202is a ball valve having a suction-line valve body206and a suction-line valve ball208rotatable within suction-line valve body206. Suction-line valve ball208has a first end212, an opposing second end214, and a suction-line valve channel210running between the two ends212,214. Suction channel210is configured to channel fluid from first end212to second end214when ball valve is in an open position. Specifically, in an embodiment, suction-line valve channel210is configured to channel refrigerant136through suction-line valve ball208when suction-line valve ball208is in an open position. Suction-line valve ball208is also configured to prevent the flow of refrigerant136through suction-line valve202when suction-line valve ball208is in a closed position (i.e. when suction-line valve ball208is rotated such that fluid cannot flow through suction-line valve channel210; shown inFIG. 2).

HVAC system100also includes a liquid-line valve204located along liquid line142between condenser184and evaporator192. Liquid-line valve204is configured to control the flow of refrigerant136through liquid line142to expansion device188and evaporator192. In an example embodiment, liquid-line valve204is a ball valve having a liquid-line valve body216and a liquid-line valve ball218rotatable within liquid-line valve body216. Liquid-line valve ball218has a first end222, an opposing second end224, and a liquid-line valve channel220running between the two ends222,224. Liquid-line valve channel220is configured to channel fluid from first end222to second end224when ball valve is in an open position. More specifically, liquid-line valve channel220is configured to channel refrigerant136through liquid-line valve ball218when liquid-line valve ball218is in an open position. Liquid-line valve ball218is also configured to prevent the flow of refrigerant136through liquid-line valve204when liquid-line valve ball218is in a closed position (i.e. when liquid-line valve ball218is rotated such that fluid cannot flow through liquid-line valve channel220; shown inFIG. 2).

Suction-line valve202and liquid-line valve204are operatively coupled to an actuator228configured to actuate both valves202,204. Actuator228is also coupled to main control module108. Main control module108controls the operation of actuator228, which, in turn, controls the actuation of valves202,204. Specifically, actuator228is configured to rotate suction-line valve ball208and liquid-line valve ball218within their respective valve bodies206,216. Main control module108is configured to control the rotation of suction-line valve ball208and liquid-line valve ball218using actuator228. In some embodiments, main control module108and/or actuator228may be configured to independently control the operation of suction-line valve202and liquid-line valve204. Alternatively or in addition, in some embodiments, main control module108and/or actuator228may be configured to actuate both valves202,204simultaneously.

FIG. 2ais a schematic diagram of an embodiment of suction-line valve ball208and liquid-line valve ball218in a first rotation configuration250. As shown inFIG. 2a, suction-line valve ball208and liquid-line valve ball218may be the same size or may be substantially similarly size and may have the same or similar angular offset relative to suction-line valve body206and liquid-line valve body216. More specifically, both suction-line valve202and liquid-line valve204have a direction of flow234for refrigerant136, and an axis236transverse to direction of flow234. Both a centerline230placed midway through suction-line valve channel210and a centerline232placed midway through liquid-line valve channel220have the same or substantially similar angular offset238relative to axis236. In other words, suction-line valve ball208and liquid-line valve ball218are configured such that as both are actuated by actuator228and rotate within suction-line valve202and liquid-line valve204, respectively, the angles between centerlines230,232and axis236are the same or substantially similar.

FIG. 2bis a schematic diagram of an alternative embodiment of suction-line valve ball208and liquid-line valve ball218in a second rotation configuration252. Like in first rotation configuration250, in second rotation configuration252, suction-line valve ball208and liquid-line valve ball218may be the same size or may be substantially similarly size. Unlike in first rotation configuration250, in second rotation configuration252, suction-line valve ball208and liquid-line valve ball218have a different angular offset relative to suction-line valve body206and liquid-line valve body216. More specifically, suction-line valve centerline230has a first angle240relative to axis236and liquid-line valve centerline232has a second angle242relative to axis236, and second angle242is different from first angle240. In an embodiment, an angular offset244between suction-line valve ball208and liquid-line valve ball218is greater than about 5 degrees and less than about 45 degrees. In further embodiments, angular offset244is greater than about 5 degrees and less than about 25 degrees. In alternative embodiments, angular offset244is any degree difference that allows HVAC system100to function as described herein.

In embodiments of first rotation configuration250and second rotation configuration252, suction-line valve ball208and liquid-line valve ball218may be the same size or may be substantially similarly size. However, in some embodiments, suction-line valve channel210has a larger diameter than liquid-line valve channel220. More specifically, in some embodiments, suction-line valve channel210has a diameter that is about the same or less than the diameter of suction line138and liquid-line valve channel220has a diameter that is about the same or less than the diameter of liquid line142. In some embodiments, suction-line valve channel210is about ¾ inch to about 1 inch in diameter and liquid-line valve channel220is about ¼ inch to about ½ inch in diameter. In further embodiments, suction-line valve channel210is about ⅞ inch in diameter and liquid-line valve channel220is about ⅜ inch in diameter.

FIG. 3is a schematic diagram of an example rotation sequence300for actuating suction-line valve202and liquid-line valve204. In rotation sequence300, suction-line valve202and liquid-line valve204are configured relative to each other according to second rotation configuration252. In an embodiment, main control module108is configured to, by means of actuator228(shown inFIG. 1), sequentially actuate suction-line valve202and liquid-line valve204. More specifically, main control module108is configured to actuate valves202,204between four base positions302,304,306,308to create on full rotation sequence300.

In first position302of rotation sequence300, both suction-line valve202and liquid-line valve204are in a closed position, preventing refrigerant136from flowing through channels210,220, respectively. More specifically, in first position302, valve balls208,218are rotated within valve bodies206,216such that channels210,220are open only to the sides of valve bodies206,216. In operation, while rotation sequence300is in first position302, all or most of refrigerant136is contained between suction-line valve202and liquid-line valve204fluidly upstream of suction-line valve202and fluidly downstream of liquid-line valve204. As such, in the first position, all, substantially all, or most of refrigerant136is located in outside area101and within condensing unit178. Advantageously, in some embodiments, when rotation sequence300is in first position302, flammable refrigerant136is removed from structure102, decreasing the risks to structure102.

In second position304, suction-line valve202is in the closed position, preventing fluid from flowing therethrough, and liquid-line valve204is open, allowing refrigerant136to travel from first end222to second end224of liquid-line valve channel220. Accordingly, in second position304, refrigerant136begins to travel from condensing unit178in outside area101into structure102. In other embodiments, both suction-line valve and liquid-line valve are in the open position in second position304. In third position306, both suction-line valve202and liquid-line valve204are in an open position, allowing refrigerant136to flow through channels210,220, respectively. Accordingly, in operation, when rotation sequence300is in second position304and third position306, refrigerant136flows through liquid line142from condensing unit178to expansion device188and evaporator192. In these two positions304,306, evaporator192cools blown air107to generate cool supply air132.

In fourth position308, suction-line valve202is open, allowing refrigerant136to flow from first end212to second end214of suction-line valve channel210, while liquid-line valve204is closed, preventing refrigerant from traveling therethrough. In operation, in fourth position308, refrigerant136is pumped down out of structure102and into condensing unit178. In this example, most of the refrigerant136is removed from structure101while rotation sequence300is in fourth position308. In other embodiments, 75% or more of refrigerant136is removed from structure101while rotation sequence300is in fourth position308. In further embodiments, 90% or more of refrigerant136or, alternatively, substantially all of refrigerant136is removed from structure101while rotation sequence300is in fourth position308.

After fourth position308, rotation sequence300returns to first position302. Operationally, returning to first position302means that most, 75% or more, 90% or more, or substantially all of refrigerant136is removed from structure102and moved to outside area101between suction-line valve202and liquid-line valve204fluidly upstream of suction-line valve202and fluidly downstream of liquid-line valve204and at least partially within condensing unit178. Accordingly, one full rotation sequence300represents one cooling cycle of HVAC system100that includes one full pump-down procedure to remove most, 75% or more, 90% or more, or substantially all of the refrigerant from structure102.

Suction-line valve202and liquid-line valve204are located in outside area101and outside of condensing unit178such that valves202,204are accessible without entering condensing unit178. With valves202,204located outside of the condensing unit178, a service technician can access valves202,204, and thus refrigerant136, while refrigerant136is contained within condensing unit178between suction-line valve202and liquid-line valve204(i.e. when valves are in first position302). Accordingly, a Schrader valve or other service valves are not required to service at least some embodiments of HVAC system100. In alternative embodiments, valves202,204are located within at least a portion of condensing unit178. In some of these embodiments, valves202,204are accessible within condensing unit178through a service access panel (not shown).

Valves202,204are actuated in parallel, such that both valve balls208,218rotate at substantially the same speed throughout one full rotation sequence300. In alternative embodiments, valves202,204may be actuated sequentially or their actuation may be offset. Further, channels210,220may have alternative configurations, such as, for example, slots instead of round holes.

FIG. 4is a schematic view of a valve actuation system400utilizing a motor and a shaft to actuate valves202,204. In this embodiment, actuator228is a motor402having a shaft404coupled to a first end406. Shaft404is operatively coupled to suction-line valve202and liquid-line valve204such that rotation of shaft404causes a corresponding rotation of suction-line valve ball208and liquid-line valve ball218. In such a configuration, both valve balls208,218rotate in unison. Accordingly, motor402is configured to rotate valves202,204from first position302to second position304to third position306to fourth position308and back to first position302.

Valve actuation system400may include a position sensor408configured to determine the angular position of suction-line valve ball208and liquid-line valve ball218within suction-line valve202and liquid-line valve204, respectively. Position sensor408may be, for example, a rotary and/or angular encoder or a Hall-effect device. If position sensor408is an encoder, it may be a magnetic or optical encoder and it may be configured to provide either absolute or incremental output, or both. In other embodiments, position sensor408may be any sensor that allows for valve actuation system400to function as described herein. As illustrated, position sensor408is located on shaft404within motor402. However, it will be appreciated that position sensor408may be located anywhere valve actuation system400that allows position sensor408to function as described herein.

In the illustrated embodiment and as described above, motor402is operatively coupled to main control module108and main control module108controls the operation of motor402and, by extension, shaft404and valves202,204. However, other configurations are contemplated within the scope of this disclosure. In some embodiments, motor402and/or valves202,204may be operatively coupled to a separate controller (not shown) distinct from main control module108. This separate controller may in turn be controlled by main control module108or may operate independent of main control module108. For example, valves202,204may be operatively coupled to a cam and switch system or other similar system configured to control the operation of valves202,204.

FIG. 5is a schematic view of an example valve operation system500. Similar to valve actuation system400, in valve operation system500, actuator228is a motor402having a shaft404coupled to a first end406. Shaft404is operatively coupled to suction-line valve202and liquid-line valve204such that rotation of shaft404causes a corresponding rotation of suction-line valve ball208and liquid-line valve ball218, rotating both valve balls208,218in unison. In this example, valve operation system500also includes a position sensor408.

A motor wire502operatively couples main control module108to motor402. Main control module108is configured to control the operation of motor402and, by extension, actuation of valves202,204. In an embodiment, when thermostat122has a reading above a particular set point, thermostat122transmits a signal to main control module108, which, in turn, activates motor402to begin actuating valves202,204according to rotation sequence300. The actuation of valves202,204according to rotation sequence300causes refrigerant136to be pumped into structure102to cool air107before refrigerant136is pumped down from structure102back into condensing unit137. The cycle is repeated as necessary to maintain the temperature at the thermostat122set point.

A sensor wire504operatively couples main control module108to motor position sensor408. Sensor wire504enables position sensor408to transmit position information of shaft404to main control module108. Based on the information received from position sensor408, main control module108can change an operation of motor402, such as, for example, increasing or decreasing the speed of motor402. In some embodiments, the information from position sensor408can be used diagnostically in order to determine a defect in the actuation of valves202,204and/or a defect in motor402, such as wear or contamination in motor402or shaft404. If a defect is detected, main control module108is configured to perform an additional operation, such as, for example, terminate operation of motor402or notify the operator of an error.

Motor402may be a direct current (DC) motor, a stepper motor, or an alternating current (AC) motor. Motor402may include position sensor408. In some embodiments, the time between two positions of shaft404may be determined and the detected time difference compared to an expected value can indicate an error has occurred in valve operation system500, such as wear or contamination in motor402or shaft404. In embodiments where motor402is a stepper motor, main control module108may be configured to monitor the number of steps performed by motor402versus the position of shaft404. Using the number of steps compared to the position, main control module108can detect errors that may occur. For example, if the number of steps recorded by control module118does not correspond to the expected position of shaft404, the detected difference can indicate an error has occurred in valve operation system500. If an error is detected based on readings from position sensor408and/or the number of steps, main control module108is configured to perform an additional operation such as, for example, terminate operation of motor402or notify the operator of an error.

Motor402may include a gear train, such as a simple or planetary gear train. In some embodiments, the gear train may provide additional torque to shaft404, which in turn provides additional torque to suction-line valve202and liquid-line valve204in order to rotate suction-line valve ball208and liquid-line valve ball218.

FIG. 6is a schematic view of an example alternative valve operation system600. Valve operation system600is similar to valve operation system500. Valve operation system600includes an enclosure602surrounding suction-line valve202and liquid-line valve204such that both valves are within a cavity604. In this embodiment, motor402is located outside of enclosure602with shaft404extending through enclosure602to valves202,204. Enclosure602is configured to contain any fluid, such as refrigerant136, that may leak form valves202,204during operation of valve operation system600. In an embodiment, shaft404passes through a sealing body606within a wall of enclosure602. Sealing body606helps isolate cavity604from outside are101and prevents leakage of fluid out of cavity604along shaft404. In some embodiments, sealing body606includes a rubber or polymer ring.

FIG. 7is a schematic view of an example alternative valve operation system700.FIG. 8is a schematic view of alternative valve operation system700used in conjunction with HVAC system100. Like valve operation system600, valve operation system700includes enclosure602surrounding valves202,204. In valve operation system700, motor402is also contained within cavity604of enclosure602. In some embodiments, motor wire502and sensor wire504are at least partially encased within a water-resistant material702, preventing contact with any fluid that leaks from valves202,204. In further embodiments, water-resistant material702hermetically seals motor wire502and sensor wire504. In some embodiments, water-resistant material702extends through sealing body606within a wall of enclosure602. In further embodiments, a line sealing body704extends along a wall of enclosure602and water-resistant material702extends through line sealing body. Accordingly, in some embodiments, line sealing body704helps isolate cavity604from outside are101and prevents leakage of fluid out of cavity604along water-resistant material702. In some embodiments, line sealing body704includes a rubber or polymer ring.

As shown inFIG. 8, in some embodiments of valve operation system700, suction line138extends into and out of cavity604through line sealing bodies704within the walls of enclosure602, allowing suction line138to fluidly connect with suction-line valve202. Similarly, liquid line142extends into and out of cavity604through line sealing bodies704within the walls of enclosure602, allowing liquid line142to fluidly connect with liquid-line valve204. In some embodiments, a similar configuration allows for connection of suction line138and liquid line142to valve operation system600.

It will be appreciated that the configuration of valves202,204, motor402, and shaft404shown in valve operation systems500,600,700are provided for illustrative purposes and that other configurations are contemplated within the scope of this disclosure. For example, as illustrated by valve operation system800inFIG. 9, in some configurations, motor402is located between suction-line valve202and liquid-line valve204and shaft404extends from first end406to liquid-line valve204and from a second end802to suction-line valve202. Additionally, like systems600and700, valve operation system800may include one or more enclosures602(shown inFIGS. 6 and 7), isolating valves202,204and/or motor402from outside area101.

FIG. 10is a schematic view of an alternative valve configuration900having dedicated service valves. Valve configuration900includes a suction-line service valve902coupled to suction-line valve202and a liquid-line service valve904coupled to liquid-line valve204. In an embodiment, service valves902,904are Schrader valves. In alterative embodiments, service valves902,904are any valves that allow valve configuration900to operate as described herein.

Valve configuration900is configured to perform rotation sequence300and pump down refrigerant136from structure102at the end of each cooling cycle. Specifically, the pump down process (i.e. the transition from fourth position308to first position302) causes refrigerant136to be isolated within condensing unit178between suction-line valve202and liquid-line valve204. If, during a service process, a technician desires to monitor pressures or remove or replace refrigerant, valves902,904may be used to access refrigerant136isolated within condensing unit178. It will be appreciated that one or both valves902,904may be used to access refrigerant136. It will also be appreciated that suction-line valve202and/or liquid-line service valve904may be placed in other positions within HVAC system that allow access to refrigerant while stored in condensing unit178.

Embodiments of the cooling systems described help reduce and/or mitigate potential risks associated with the flammability of certain refrigerants by pumping down the refrigerant within the cooling system from an interior space to an exterior module between each cycle of the cooling system. Accordingly, the cooling systems described allow for the use of at least mildly flammable refrigerants and thus provide the ability to replace refrigerants with high GWP with refrigerants with lower GWP, reducing the potential environmental impacts of the cooling systems. Further, actuation of valves within the cooling systems allows for refrigerant stored in a condensing unit to flow into a structure in a controlled manner, preventing flooded start conditions and reducing or alleviating the need for the compressor to start under pressure. In some embodiments, the traditional service valves are replaced altogether, reducing the overall cost associated with adding the pump down functionality to the HVAC system.

It will be appreciated that the above embodiments that have been described in particular detail are merely example or possible embodiments, and that there are many other combinations, additions, or alternatives that may be included.