Patent Publication Number: US-2013241194-A1

Title: Weldless aluminum based hvac system and method of making

Description:
PRIORITY/CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the following U.S. Provisional Application Nos. 61/433,469, filed Jan. 17, 2011; 61/425,595, filed Dec. 21, 2010; 61/420,146, filed Dec. 6, 2010; and 61/373,754, filed Aug. 13, 2010, the disclosures of which are incorporated herein by this reference. 
    
    
     TECHNICAL FIELD 
     The presently disclosed and claimed inventive concept(s) generally relates to a system and method for assembling a system for use in HVAC in buildings, and more particularly to an HVAC system based on use of aluminum tubing and the connectors that make that system possible. 
     BACKGROUND 
     For the past 50 years or so the standard procedure for installing HVAC equipment using copper tubing has been carried out either by mechanical means (flaring copper tube and using brass unions) or by brazing/soldering. Flaring of copper tubing is notoriously unreliable and is the source of a lot of refrigerant leaks in the field. If carried out correctly flaring is a sound method. The problem is it is seldom carried out properly and failures are numerous. 
     In the past soldering of copper tube was commonly used and was used with some success as the refrigerants at the time were of a low pressure, typically R12, R22, R11 and methyl chloride. Even so, solder was not good in areas of vibration and high temperature and many leaks occurred. Its one saving grace from an installation point of view was that solder melts at a very low temperature so it was easy to apply and caused no internal contamination of the tube as no oxidation takes place at low temperature, therefore the tube stayed relatively clean. 
     Brazing of copper tube is much the preferred method of connecting field tubing as it makes a much stronger connection if carried out properly, and is suitable for all the new generation of high pressure gases that are commonly found today, R502, R134A, R410A, R407A, 410A and R407C. However, the downside of brazing is that very high temperatures are involved, typically in the 900 degrees C. range. A reasonably high level of skill is required to make sound joints, and contamination is a big issue. A new problem has also arisen in recent years regarding health and safety with the introduction of hot works permits. 
     In many situation now hot works permits are required before work can commence and these typically impose restrictions on when and where brazing can be carried out. This requirement translates into added costs and delays, is time consuming and inefficient and increasingly hot works are banned altogether. 
     When brazing takes place a huge amount of oxidation takes place inside the tube. Black soot forms from impurities in the air and this has to be combated by the purging of dry nitrogen through the tubing while the brazing is taking place. Nitrogen purging is time consuming, irksome, expensive and rarely carried out, with the result that many systems are commissioned with heavily contaminated tubing which results in a catalogue of problems later on. The main failures due to contamination are contaminated compressor oil resulting in compressor failures, blockages of small tubes in the system resulting in control box failures and valves. 
     An added concern is the excessive production of CO2, a greenhouse gas, during the production of copper tubes. This added expense of copper makes a system that can be adapted to tubing other than copper, such as aluminum, very desirable. 
     HVAC systems around the world are made using copper tubes, which are fitted into brass or copper fittings. One of these systems is called a VRF air conditioning system. Aluminum is a much cheaper material than copper, and aluminum production creates far less carbon dioxide, a major greenhouse gas, than copper production. Aluminum costs roughly half of what copper does. There is thus a huge economic and environmental incentive for making HVAC systems based on aluminum tubing. The reason that such a system has not been used in the past is that fittings were not available which would connect aluminum tubes in a way that was leak free, and connectors made of metals other than aluminum would result in galvanic corrosion between the aluminum tubing and the non-aluminum fitting. Aluminum is not amenable to brazing or welding in the field. 
     A major cause of thread failure within a building or process plant environment is galvanic corrosion—where the carbon steel pipe directly meets a brass valve, or is transitioned to copper pipe. Here, the microvolt difference in electrical potential of the metals will produce a small current between them—the result of which is to greatly accelerate the deterioration of the more reactive and often termed “less noble” carbon steel pipe. 
     In effect, an extremely small DC electrical circuit is created, with the steel pipe serving as the anode, the brass fitting or copper pipe acting as the cathode, and the water serving as a weak wire connection completing the circuit. In simplest terms, a very weak battery is created. Use of aluminum tubing with brass, copper, or steel has the same result: rapid corrosion. 
     “Galvanic” corrosion occurs between any two dissimilar metals in contact with each other and water, and typically attacks the steel pipe to a degree somewhat dependent upon existing corrosion conditions. Galvanic corrosion is defined as an electrochemical reaction of two dissimilar metals in the presence of an electrolyte, typically water, and where a conductive path exists. It is visually recognizable in its latter stages by some degree of deposit buildup where the dissimilar metals meet at the threads—creating a microfine leak. At that point, however, most of the damage has already occurred and replacement is required. 
     The global market for air-conditioning systems has risen dramatically in the last decade and looks set to continue to expand. Currently, the most advanced air-conditioning system in common use is the VRV or Variable Refrigerant Volume system. 
     A network of copper pipes is installed around the building to supply refrigerant from the HVAC core (refrigerant source) to the relevant cooling coils (“air handlers”, or distributed cooling units) in the required areas. As the copper pipes extend from the refrigerant source to the distributed cooling units, the copper pipes split into smaller and smaller tubes. The splitting of one tube into two, with one going to a fan coil, and the other continuing on to other fan coils, is accomplished at a y joint called a refnet in the prior art. The prior art refnet connections are welded together from a number of parts, and requires multiple welds for each Y joint. There has been no connection other than welding which ensured a leak free fitting when using copper pipes, the industry standard. The welds have to be in a nitrogen environment. With so many welds there is fire hazard, and the welds require trained and highly paid personnel to accomplish the welding. One type of refnet junction is formed from an incoming pipe that splits at the junction into two outgoing pipes. Each of the three pipes has stepped down diameters to match the requirements for that particular refnet junction. One way in which this is accomplished is to use a pipe with built in size reductions, then just cutting off the pipe in the region of pipe diameter that matches the size of the system pipe to be attached. 
     When the component is to be fitted, the diameter of the pipe is determined and the correct diameter section of the component is welded on. This is a cumbersome operation, especially since it is necessary to purge the weld region with nitrogen in order to prevent oxidation of the metal. Accordingly, the connection of tubing component to pipe is intricate and subsequently expensive and prone to error and fire risk, and takes an excessively long time to complete, and requires specialized and expensive technicians to build. 
     Besides refnet junctions, the HVAC system requires at least two other types of connections. One type joins two copper tubes together, and another type joins a flared copper tube to a brass fitting with an internal thread opposite the flared tube fitting. An aluminum tubing based HVAC system requires joints sufficiently tight that no leakage occurs and which prevents galvanic corrosion at the fittings. If this could be accomplished, a great savings in cost would be realized, an environmentally favored solution could be achieved, and projects could be built faster and cheaper. 
     It is an object of the present invention to provide an HVAC system based on aluminum tubing rather than copper tubing 
     It is a further object of the present invention to provide a type of refnet junction forming assembly to allow refnet junctions to be fabricated on the job site, without welding, to match the size and pressure specifications of the HVAC system. This on-site fabrication is designed to securely seal the system so that refrigerant gasses will not escape, eliminate all welding steps. By eliminating the welding step, the assembly is much less of a fire hazard. Such a system can also be assembled without hiring the highly skilled welders required by the prior art, and greatly shortens the fabrication time. 
     It is a further object of the present invention to provide a type non-conducting and non-corroding connector for connecting two aluminum pipes in a leak free junction. 
     It is a further object of the present invention to provide a type non-conducting and non-corroding connector for connecting an aluminum tube to a threaded fitting. 
     SUMMARY 
     The disclosed technology allows the joining of high pressure, high pressure tubing without the use of heat for uses such as carrying refrigerant. It also allows assembling a system using joints and tubing of dissimilar metals, such as copper, steel and aluminum, while achieving an unbreakable connection that massively exceeds its field application. The disclosed technology has gained ETL listing to U.L. 207 which requires components to survive a 3000 psi pressure test which is far higher than anything practically required. 
     The disclosed technology system dispenses with the need for skilled brazing personnel, nitrogen purging, hot works permits and even use of copper tubing for carrying refrigerant. The disclosed technology is able to dispense with the use of expensive copper tube because of the use of dielectric coated fittings. This coating prevents the corrosion through electrolysis of the tubing and allows the joining of aluminum and copper tubing, and use of brass and steel fittings. The ability to use aluminum in high pressure refrigerant lines is the first time ever in the history of HVAC that relatively inexpensive aluminum tubing can totally replace the more expensive copper. 
     An HVAC system built by the disclosed technology uses computer aided design to develop the specifications of the system, and then a relatively small selection of fittings and tools are used to fabricated on-site, without welding, brazing or soldering, the multiple tubing connections in the system. One part of the system is a part that replaces the prior art refnet junction, and is called a Y or tri connector. The assembly of tools and parts which can be used to make a tri connector also serves to make other connections of tubing. The tri connector is a hub of steel, into which three steel connectors with one threaded end and one press fit end are threaded into the hub. The connectors are coated with a dielectric layer to prevent electrical contact between parts. By making the hub of steel with threaded openings, steel press-thread connectors can be assembled to form a tri connection which is totally gas proof and able to withstand high pressures. With a limited number of hubs, press-thread connectors, and press connectors, and pressing tools, and locking rings, a system can be constructed from a greatly reduced inventory of parts, on site, with no welding. 
     A dielectric connector designed to join different types of metal pipe together, without welding brazing or soldering, is another component of the system. For instance, if a copper tube and a steel fitting were joined, electrical separation would be necessary as the combination of metals under solder could produce galvanization, leading to corrosion and failure of the pipe. The same would be true of aluminum touching steel, or copper touching aluminum. The connector can be of several versions, but each version has a first end that presses together to hold a section of tubing. The second end of the connector can be a mirror image of the first end, or can be a threaded portion, or can be the equivalent of a flare nut. The connector is generally cylindrical and is preferably made of steel, coated inside and out with a dielectric coating. Surrounding the connector body are at least two ring-like tool ridges which encircle the connector body generally in the center of the connector body. To one side of the tool ridges is a first flange on a first end of the connector body and to the other side of the connector body is a second flange on the second end of the connector body. Each flange is encircled by a sealing ridge, and has an interior surface which extends through the connector body. On the interior surface is a ridge which is provided to abut the end of a tube inserted into the connector body. There is a first ridge on the first end and a second ridge on the second end, both in the interior surface of the connecting body. The connector body is covered inside and out with a dielectric material, namely a dielectric plastic, or some other suitable nonconducting material, which is plated onto the connector body on the interior and the exterior by an electric plating method. The dielectric material which covers the steel connector allows tubing sections of dissimilar metals to be joined to the steel connector. Thus, combinations of brass, copper, and aluminum tubing may all be joined to the steel connector without causing cathodic corrosion. The dielectric material is typically from 15-20 microns in thickness. 
     The use of steel connectors for the aluminum tubing allows the seal to be secure to gas leakage, by sandwiching the aluminum tubing end between an unyielding steel tubing insert and the steel connector, with pressure applied by a steel connector nut which is pressed onto the connector body. A tool gripping ridge in the middle of the connector are tool ridges and are provided for engagement by the jaws of the pressing tool. The connector, connector nut, and tubing inserts can also be zinc plated. 
     The disclosed technology also includes pressing tools for pressing the connector nut onto the connector body. This requires a lot of force, since the act of pressing the connector nut onto the connector body sandwiches the end of the tubing between the steel tubing insert and the inside of the connector body. The pressing tool has an upper clamp body and a lower clamp body. The two clamp body sections are attached to each other using rods for alignment, with the two clamp body sections being configured to move toward and away from each other. Springs on the rods press the two body sections apart. A hydraulic line is attached to the lower clamp body, and when activated presses the two body sections together by hydraulic force. 
     There is a hydraulic cylinder below each of the two rods, and the two rods form the piston in the cylinders. Hydraulic fluid enters the two cylinders, and forces the pistons toward the bottom of the lower clamp body. 
     Each of the lower and upper body sections have a top side, a bottom side, facing sides, outfacing sides, left sides, and right sides. Each of the body sections define a generally cylindrical passage, extending from the facing sides to the outfacing sides. This passage is a partial cylinder, and would vary in size depending on the size of the tubing and fittings being worked on. 
     In each of the body sections, in the semi-cylindrical passage, are located semi-cylindrical cutouts, forming support positions for the insertion of jaws. The jaws are semi-cylindrical, and have a protruding interior ridge, or tool grip ridge. The tool grip ridge is consistent with a corresponding ridge on the connector, and the ridge on each jaw presses against the ridge on the connector to press the pipe into the fitting. The joining of the aluminum or copper pipe to the fitting includes an inner locking collar also called a tube insert, which sandwiches the pipe between the wall of the fitting and the inner locking collar. An outer locking collar is simultaneously pressed onto the outside of the fitting. 
     A second embodiment of the disclosed pressing tool comprised of two sections which are rotationally attached to each other. Each half is polygonal in shape, such as a hexagon, and on each of several of the hexagonal sides is located a jaw sized for engagement with a tool sealing ridge of a particular size of connector. Each jaw can be for a different size of connector, and the two sections can rotate in relation to each other. Thus the two sections can be rotated to hold different sized of connectors, including connectors with two different size ends. An example of this device would be hexagonal, with different sizes of jaws on 4 to 6 of the sides. 
     In each of these embodiments, the sections are pressed toward each other by hydraulic means, which can be a foot pedal or a hydraulic motor. This version of the device works with smaller sized connectors than the version discussed above, and also works with connectors with different sized ends, i.e. adapters, which connect tubing of two different diameters. 
     In the second embodiment of the pressing tool, the two sections are joined by a rod, as in the first embodiment, with the rod surrounded by a spring which forces the two sections apart. The rod is the piston of a hydraulic cylinder and forces the two sections together when activated, to secure the pipe end between an outer locking collar, an inner locking collar, and the flange of the connector. A side of the connector is secured to a pipe end, then the connector is reversed to secure a pipe end to the other side. A locking pin secures the two parts of the rotational press, and retains their alignment as they are used to press a connection into engagement with a tubing section. 
     The invention also includes a method of forming HVAC systems using weldless joints and aluminum tubing or other similar metals to form the system. The steps of the method include analyzing the HVAC needs of a building and determining the required configuration of the refrigerant source(s), the distributed cooling units and the tubing network that is required to join them and provide adequate refrigerant capacity. The tubing network includes sections of tubing, which would typically be aluminum tubing, connectors which join two tubing sections together, and connector hubs which form a Y and allow a refrigerant line to be split into two and subsequently other tubing lines. 
     Once the cooling needs of a building are analyzed the physical position of each Y connection is determined using the building plans. The next step is building each Y connection with the three hub connectors that come out of the connector hub, being sized to the appropriate size and ready to be connected to tubing sections. The next step is attaching hub connectors into the connector hub, with each hub connector having a dielectric layer outside and inside, and a press fit first end and threaded second end. The threaded second end is threaded into the connector hub. 
     The next step is cutting sections of aluminum tubing to connect the source of refrigerant to the Y connections and to the distributed cooling units. 
     The next step is forming joints between aluminum tubing and the Y connectors by inserting a tubing insert in the end of the tubing sections, placing a connector nut on each end of the tubing sections, placing the tubing end in a connector body on the press fit end of the connectors, and pressing the connector onto the connector body to form a tight, weldless joint without the addition of heat to form a joint. 
     The next step is determining where sections of tubing need to be connected to other sections of tubing, including locations where the tubing diameter needs to change in the pathway of the refrigerant. 
     The next step is forming joints between the aluminum tubing sections by the use of the tubing connectors, using the tubing insert and the connector nut as described above. 
     The invention is also a method of joining tubing sections in order to assemble a refrigeration system, which is made of the following steps: 
     The first step is inserting a tube insert into the end of a first tube section to be joined to a second tube section. 
     The next step is placing a connector nut onto the first tube end and sliding it a short distance up the first tube end. 
     The next step is applying a locking preparation fluid on a portion of the tube end, on an exterior surface of the tube end. 
     The next step is placing the tubing end into a connector flange of a connector body, with the connector made of steel and being a generally cylindrical tubing connector body as described above. The tubing is placed so that it rests against the ridge on the interior of the connector. 
     The next step is placing the first tube, and the tube insert with the locking ring on the first tube, into a two piece press with the press including a first jaw for engagement with the outer end of the connector nut, and a second jaw for engagement with one of the tool grip ridges on the connector. 
     The next step is developing hydraulic pressure for pressing the two pieces of the press together and forcing the connector nut over the connector flange, with one end of the tube sandwiched between the tube insert and the inside of the connector flange. Hydraulic pressure may be developed by a foot press or by other hydraulic press means. A foot press is advantageous because it can be used on a job site which does not yet have electricity. 
     The next step is repeating these steps on the end of a second tube, so that two tubes are joined to the connector. Using the steel connector, coated with a dielectric material, dissimilar metals may be joined together. For instance, any combination of brass, copper, or aluminum tubes may be joined in this manner to the connector, and not cause cathodic corrosion of the connector or of the tubings. The result of this adaptability in the use of materials results in refrigeration and HVAC systems finally being able to use aluminum tubing, which has never been the case before and which will revolutionize the industry. Aluminum is less costly than copper, and this method eliminates the need for welding the joints in HVAC systems. The cost savings in the industry will drive widespread adoption of this technology. 
     The method can also include the steps of using zinc plated tube inserts and connector nuts, with the zinc plated to a thickness of approximately 8 microns. 
     The purpose of the Abstract is to enable the public, and especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection, the nature and essence of the technical disclosure of the application. The Abstract is neither intended to define the inventive concept(s) of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the inventive concept(s) in any way. 
     Still other features and advantages of the presently disclosed and claimed inventive concept(s) will become readily apparent to those skilled in this art from the following detailed description describing preferred embodiments of the inventive concept(s), simply by way of illustration of the best mode contemplated by carrying out the inventive concept(s). As will be realized, the inventive concept(s) is capable of modification in various obvious respects all without departing from the inventive concept(s). Accordingly, the drawings and description of the preferred embodiments are to be regarded as illustrative in nature, and not as restrictive in nature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of the overall HVAC system. 
         FIG. 2  is an exploded view showing a tubing connector and connector nuts. 
         FIG. 3  is a cutaway view of a disclosed hub connector. 
         FIG. 4  is a cutaway view of a disclosed tubing connector. 
         FIG. 5  is a joint of the system, with two tubing sections which can be dissimilar metals or different sizes. 
         FIG. 6  is a disclosed Y connection. 
         FIG. 7  is a view of a prior art refnet junction. 
         FIG. 8  is a side cross section of a disclosed flare nut connection. 
         FIG. 9  is a side cross section of a disclosed flare nut connection. 
         FIG. 10  is a view of a tubing end and a tubing insert, part of the method of joining aluminum tubing in a weldless joint. 
         FIG. 11  is a view of a tubing end and a tubing connector, part of the method of the joining aluminum tubing in a weldless joint. 
         FIG. 12  is a view of a connector nut sliding onto a connector body, part of the method of joining aluminum tubing in a weldless joint. 
         FIG. 13  is a view of a joint formed on a tubing end, part of the method of joining aluminum tubing in a weldless joint 
         FIG. 14  is a view of a tubing connector joining two sections of tubing, part of the method of joining aluminum tubing in a weldless joint 
         FIG. 15  is a view of a disclosed tool for forming joints. 
         FIG. 16  is a view of a disclosed tool for forming joints. 
         FIG. 17  shows the steps in the method of forming of an HVAC system with weldless joints. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     While the presently disclosed inventive concept(s) is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the inventive concept(s) to the specific form disclosed, but, on the contrary, the presently disclosed and claimed inventive concept(s) is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the inventive concept(s) as defined in the claims. 
     Shown in  FIG. 1  is a diagram of a refrigerant system of the disclosed technology. Also shown in  FIG. 1  are links of tubing  34 , which are connected to fittings with a connector  12 , which may be of the type designated a press-press connector, which refers to both ends of the connector being a press fitting. The system also includes connectors which are press/thread connectors in which one end of the connector is joined to tubing by pressing, and the other end is joined to a fitting by threads. Shown are Y connectors  26 , which involve the use of press-thread connectors  28 . Each of these fittings will be discussed as they appear in more detail in this document. The system as a whole is made up of parts which are configured to be assembled on a job site without welding. All of the fittings together form a system which is capable of holding a very high pressure, which involves the use of dissimilar metals, with each of the fittings and tubing sections configured to be connected to each other in a corrosion free high pressure joint, and to be assembled on the job site with no requirement for welding. 
       FIG. 2  shows a press-press connector  36 , of the invention. At either end of the press-press connector, are shown connector nuts  16 , which would typically be uncoated steel rings. Each of the connector nuts  16 , are joined to the press-press connector  36 , by being pressed on to the first end  18 , and to a second end  20 , of the connector body. The connector body is preferably a steel fitting which is covered inside and out by a dielectric coating  24 , which insulates the connector from electrical discharges and corrosion from the tubing. This feature allows dissimilar materials to be used in the system, such as aluminum tubing connected to steel fittings, and optionally with copper tubing or brass fittings. The press-press connector  36 , includes a tool gripping ridge  22 , on each end of the connector. The connector also includes a sealing ridge  38 , on each end of the connector. The press-press connector  36  can be in different sizes, depending on the requirements of the system. A typical HVAC system using the disclosed technology might be comprised of thousands of Y connectors and press-press connectors  36 , and numerous press-thread connectors  28 . 
       FIG. 3  shows a press-thread connector  28 , which is identical on one end to the press-press connector  36 , but has a thread section  40 , on the second end  20 , of the device. Included in the press-thread connector  28 , is a connector body  13 , preferably made of steel and coated with a dielectric layer  24 , which may be seen in this cross-sectional view. The connector body  13 , extends through the connector nut  16 , and is visible on the outside of the connector nut  16 . Attached to the connector body is a section of tubing  34 . A number of different types of tubing  34 , may be utilized including copper, but an important contribution of the disclosed technology system is the ability to utilize aluminum tubing in a high pressure refrigerant carrying application. Present in the threaded part of the hub connector is a seal and o ring for completing the joint. 
     Shown in  FIG. 4  is a press-press connection  36 . It includes a connector body  13 , and a connector  12 , at each of the first end  18 , and the second end  20 . Shown are two (2) lengths of tubing  34 , which are joined by the connector  12 . Each piece of tubing  34  surrounds a tubing insert  14 , at the end of the tubing. The tubing insert  14 , has a lip  42 , which prevents the tubing insert from entering the inside of the tube  34 , and which positions it on the end of each of the tubing  34 . 
     Shown in  FIG. 4  are connecting nuts  16 , which are positioned surrounding and circumvolving the first end  18 , and the second end  20 , of the connector body, and securing in place the ends of the tubing sections  34 . Each end of the connector body  13 , includes a tool gripping ridge  22 , which is utilized in forming the joint, and which allows a pressing tool to apply the pressure that seats the connector nut  16 , on to the connector body  13 .  FIG. 4  also shows a dielectric layer  24 , which coats the inside and the outside of the connector body  13 . The dielectric layer  24 , is preferably a layer approximately 10 to 24 microns thick, which is deposited by an electrical process. A suitable material for use in the dielectric coating  24 , has been found to be electrophoretic paint, but other materials with similar properties would also be suitable. 
       FIG. 5  shows a connector  12 , which joins tubing sections  34 , at a high pressure corrosion free joint. Visible in this Fig. are the connector nuts  16 , at either end of the press-press connector  36 , with the tool gripping ridges  22 , visible and a part of the connector body  13 , extending out from the connector nut  16 . In a fitting such as that as shown in  FIG. 5 , one (1) section of tubing may be aluminum, another section may be copper, or other materials may be securely attached to each other without a problem with galvanic corrosion. 
       FIG. 6  shows a Y connector  26 , of the disclosed technology. The Y connector  26 , is preferably steel, and may be coated with a dielectric coating or layer. The Y connector  26 , is preferably formed with three (3) threaded openings, into which three (3) press-thread connectors  28 , may be inserted and secured. A common use of the Y connectors is to change the diameter of the outgoing tubing to a smaller size than the incoming tubing, which would be determined by the engineering calculations of the refrigerant system. The Y connector  26 , of  FIG. 6  may be contrasted with a prior art refnet junction  44 , which is shown in  FIG. 7 . In prior art refnet junctions, an incoming pipe enters the junction and two (2) outgoing pipes leave the junction. Each of the pipes have step down diameters so the operator may choose the section of tubing with the required diameter, cut it off at that point and connect the tubing, and weld on a joint that connects to tubing of the appropriate diameter. As noted above, use of prior art refnet junction  44 , requires multiple welding steps, nitrogen purging, pressure testing and other time consuming and expensive steps. 
     Shown in  FIG. 8  and  FIG. 9  are two (2) types of connectors  12 , of the disclosed technology, which are adapted for use as flare nuts.  FIG. 8  shows a connector  12 , with a dielectric coating  24 , which covers the inside and the outside of the connector  12 . In this particular version of the connector, a generally conical flare seat  46 , is present, which fits the flared end  48 , of the tubing section  34 . Because the flare seat  46  is covered with the dielectric coating  24 , the connector  12 , may be any material, such as brass or steel and the tubing  34 , may also be dissimilar materials such as copper or aluminum. In this example, a brass male piece  50 , may be screwed in to the threaded interior of the connector  12 . The brass male piece  50 , is equivalent to prior art portions of a brass flare nut. 
       FIG. 9  shows another version of a connector which acts in an equivalent manner as a prior art flare nut. Present in this embodiment is a section of tubing  34 , which does not have a flared end  48 . Instead it ends in an un-flared end and is locked in place by the connector nut  16 , a tubing insert  14 , and a first end  18 , of a connector as has been described previously. This connector has a tool gripping ridge  22 . The connector body  13 , may be coated on the inside and outside with the dielectric coating  24 , as described in previous connectors. 
     Shown in  FIGS. 10 through 15  is the sequence in which two (2) sections of tubing  34 , are joined together. In  FIG. 10 , a section of tubing  34 , is cut off with leaving a square end. It is reamed with a tool in order to make the interior wall smooth, and a tubing insert  14 , is placed in the end of the tubing section  34 .  FIG. 11  shows a connector  12 , being placed loosely over the end of the tubing section  34 , in which the tubing insert  14 , is placed at the end. In this loose fitting, the end of the first end  18 , of the connector is marked with a marker  52 , to identify the correct positioning of the connector when it is fully inserted on to the end of the tube section  34 . 
     After marking as shown in  FIG. 11 , the connector  12 , is removed, and a connector nut  16 , is slid on to the tubing section  34 . Once the tubing connector nut  16 , is placed on the tubing section  34 , the connector  12 , is slid back in to place over the end of the tubing section  34 . A small amount of Locktite sealant is first placed on the end of the tubing section  34 , to help with the sealing of the tubing to the inside of the connector  12 . A small amount of lubricant is also placed on the sealing ridge  38 , of the connector  12 . With the connector on the end of the tubing section  34 , the connector nut  16 , is pressed on to the sealing ridge  38 , of the connector, until it is in contact with the side of the tool gripping ridge  22 , or close to contact. A preferred dielectric coating has lubricant built into the layer, but a lubricant can also be applied. This position is shown in  FIG. 13 , with the tubing  34 , attached to a first end  18 , of the connector body, and with part of the connector body  13 , extending beyond the connector nut  16 . The same process is utilized on the second end  20 , of the connector nut  12 , and two (2) tubing sections  34 , are joined to the connector  12 , as shown in  FIG. 14 . Shown in  FIG. 15  is a pressing tool of the disclosed technology which presses a connector nut on to an end of a connector. The pressing tool has a first half and a second half which are spaced apart from each other, and move toward each other under hydraulic pressure. The first half and the second half shown in  FIG. 15  is a pressing tool  56 , which includes a first half  58 , and a second half  60 . Each half has a jaw receiver  62 , which is a generally semi-circular recess which has contours which fit a first jaw  64 , and a second jaw  66 . When the jaws  64  and  66  are in place in the jaw receiver  62 , a connector  12 , is fitted with a tubing section  34 , and a tubing insert  14 , may be placed in the jaws, and a connector nut  16 , is pressed on to the sealing ridge  38 , of the connector body  13 . Hydraulic pressure may be applied through a hydraulic fitting  68 , and a hydraulic line  70 , which goes to a pump (not shown). Once the connector nut  16 , is pressed on to one (1) side of a connector, another tubing  34 , may be pressed on to the other side of a press-press connector. 
       FIG. 16  shows a different type of pressing tool which is designated as  72 . The pressing tool  72 , also has a first half  58 , and a second half  60 , and is further provided with built-in jaws  74 . The first half is configured to rotate around the second half, and the built-in jaw  74 , may be designed for a number of different sizes of connectors  12 . Using the pressing tool  72 , a connector which joins different sizes of tubing may be pressed together and form an adaptor between different sizes of tubing. 
       FIG. 17  shows the steps of forming of an HVAC system with weldless joints forming part of the method of joining aluminum tubing in a weldless joint. The steps include,  76  analyzing a building HVAC system to determine the required number, placement, and sizing of each Y connection in the system, to deliver a calculated amount of refrigerant to a plurality of distributed cooling units;  78 , establishing a physical position of each Y connection in the physical building;  80 , building each Y connection called for using an appropriately sized Y connector hub, with predetermined sizes of threaded opening, and selected hub connectors threaded into said connector hub;  82 , attaching by threading appropriately sized hub connectors into said connector hub, with each hub connector having a dielectric layer inside and outside, and a press fit first end and a threaded second end, with the threaded second end threaded into the connector hub;  84 , cutting section of aluminum tubing to connect a source of said refrigerant to said Y connections and to said distributed cooling units;  86 , forming joints between said aluminum tubing sections and said Y connectors by inserting a tubing insert in an end of said tubing sections, placing a connector nut on each of said end of tubing sections, placing said tubing end in a connector body on said press fit end of said connector, pressing said connector nut onto said connector body to form a tight, weldless joint without addition of heat to form a joint; determining where sections of tubing need to be connected other sections of tubing, including where tubing diameter changes; and  86 , forming joints between said aluminum tubing sections by use of tubing connectors which form leak proof joints with addition of heat to form said joint, by inserting a tubing insert in an end of said aluminum tubing sections, placing a connector nut on each of said end of aluminum tubing sections, placing said tubing end in a connector body on said press fit end of said connectors, pressing said connector nut onto said connector body to form a tight, weldless joint with addition of heat, as in welding, soldering, or brazing. 
     While certain exemplary embodiments are shown in the Fig&#39;s and described in this disclosure, it is to be distinctly understood that the presently disclosed inventive concept(s) is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the disclosure as defined by the following claims.