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Emerson
 
| A good installation is key to efficient and reliable performance of an a/c system. This is relevant to all types of a/c systems – splits, package, chillers, ducted, rooftops and VRF. Installing VRF systems are more challenging than regular systems due to a variety of reasons that are listed below. Each of these major reasons is a module of training and more details are available. Please send an email to digitalinfo_en@emersonclimate.com if you need more information on any of the following modules. |
| 1. R410A Applications: Even though many markets around the world are predominantly using R22, most of the VRF systems today are getting transitioned to R410A. R410A is a high pressure refrigerant and uses POE oil that is hygroscopic in nature. Many installers are not familiar with the “typical” operating pressures of R410A and this can result in less than optimal refrigerant charging in a system. If vacuuming is not properly or if the system is kept exposed to the atmosphere for extended periods of time, it will result in large amount of moisture getting absorbed by the oil and this can result in system failures over a period of time. This module will cover topics like: Refrigerant properties of R410A versus R22, handling of copper pipes for R410A and piping for large modular systems. |
| 2. Copper Pipe Sizing/Selection for VRF Systems: VRF systems are typically distributed systems – the outdoor unit is kept at a far off location like the top of the building and all the multiple indoor units are located at various places inside the building. Typically the liquid and suction lines are very long. Most manufacturers’ today claim of pipe lengths that run in several hundred of meters in length. Obviously, long pipe lengths will introduce pressure losses in the suction line and unless the correct diameter of pipe is selected, the indoor units will be starved of refrigerant and it will result in insufficient cooling to the end user. So it is very important to make sure that the pipe sizing is done properly – both for the main header pipe as well as the feeder pipes that feed each indoor unit. This module will explain in details on how to size the copper pipe for both the liquid and suction lines. |
| 3. Drain Pipe Sizing/Layout/Installation: Several indoor units are used in VRF systems and in many cases, the drain pipes have to be joined together in the overall layout to discharge the water outside. It is important to ensure that the drain pipe is sized and laid out properly. This module will explain the fundamentals of drain piping. |
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4. Wiring and Address Setting: This module discusses the way the wiring has to be done in a VRF system, how the wires have to be connected across the multiple indoor units, the cable specification to be used, the recommended distances between the power cable and control cable. Address setting is important because there are multiple indoor units and the master controller should be able to recognize the signal coming from the right indoor units and so each indoor unit is assigned an address that identifies the indoor unit and also the HP of that indoor unit. |
| 5. Copper Pipe Brazing and Flaring: There is a lot of copper pipe that is used in VRF systems and so it is important to understand the right procedure to cut, clean, handle and weld the pipes for good installation. The process of soldering is particularly important – the types of solder to be used and the way the soldering is done will determine the weld quality and this module explains all these procedures. Flaring of tubes is also important and the right procedure to be used in flaring is explained. In cases, where flange connections are used, adequate attention has to be paid to make the flange joint leak proof. |
| 6. Insulation: |
| 7. Indoor and Outdoor Unit Installation: Outdoor unit installation has to be done properly to ensure that there is no excessive sound and vibration transmitted airborne or structurally. The location of the installation is important to ensure that the hot discharge air does not get re-circulated and create abnormally high condensing pressure. In many VRF installations, several outdoor units are used in series and so special attention has to be paid for such installations. In areas, where snowfall can occur, special baffles need to be used to guard the unit. Several precautions need to be taken during the installation of the indoor units, especially for the duct type, as it may lead to sound and vibration getting transmitted. |
| 8. Pressure Test and Vacuum: In VRF systems, the pipe lengths can be very large and so the need of vacuuming is very important. In many countries, installers operate the vacuum pump for a fixed duration to ensure vacuum (pressure gauges are not used). The same procedure would not work for a VRF system because the internal volume is much larger due to the long pipe length. Special care needs to be taken for vacuuming and this module will explain the details of this process. |
| 9. Additional Refrigerant Charging: Most VRF outdoor units are pre-charged from the factory but additional charging has to be done at the site to account for the # of indoor units used and also on the combined pipe length that has been used. This module explains this procedure of charging the right amount of the refrigerant in the system. |
| 10. Test Run and Adding Oil: All manufacturers of VRF system will specify a starting procedure. The crankcase heater has to be turned on for a specified period of time and this is important to ensure that there is no flooded start. Depending on the amount of refrigerant charged in the system and the pipe length, many manufacturers recommend addition of oil. This module explains all these in more details. |
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