VRV air conditioning system, do you know

VRV air conditioning system, do you know

1.Principle of VRV system

The variable refrigerant flow (Varied Refrigerant Volume, VRV) air-conditioning system is a refrigerant type air-conditioning system. Heat exchanger, compressor and other refrigeration accessories, the end device is an indoor unit composed of direct evaporative heat exchanger and fan

　　 2. Characteristics of VRV central air conditioning system

　　 Inverter VRV air-conditioning system has obvious energy-saving and comfortable effects compared with fixed-speed systems. VRV air-conditioning system runs continuously at different speeds according to indoor load, reducing the energy loss caused by frequent compressor start and stop.

Under cooling/heating conditions, the energy efficiency ratio COP increases with the decrease of frequency. Since the compressor works in the low frequency area for a long time, the seasonal energy efficiency ratio EER of the system is greatly improved compared with the traditional air conditioning system; the compressor is started at low frequency , Reduce the starting current, electrical equipment will greatly save energy, while avoiding the impact on other electrical equipment and the grid.

　　 Advantages and disadvantages of VRV system

　　1. Advantages:

　　①Convenient design and installation, flexible layout, small building space, convenient use, high efficiency and energy saving, and low operating cost.

　　②The advanced control method, the automatic diagnosis function of the system and the advanced pipeline connection technology (the system itself has few connecting parts) have reduced the annual maintenance cost.

　　 2. Disadvantages:

　　 The initial investment in equipment is high; an additional fresh air system needs to be installed, which will waste air conditioning cooling capacity.

　　Applicable places of VRV air conditioning system

　　 is suitable for small and medium-sized hotels, guesthouses, office buildings, clubs and other places. It is more suitable for villas, apartments, duplexes, split-storey houses and small shops.

　　 Commonly used types of VRV air conditioning systems

　　1. One for one: Unit type small inverter air conditioner: There are two types of indoor units: embedded and ducted. Embedded with 3HP and 5HP. The duct type has 3HP, 5HP, 10HP, 20HP. Commonly used in various shops, small offices, restaurants and other places.

　　2, one with three (four, five) household central air conditioners: indoor units have four types: embedded, ducted, floor-mounted, and wall-mounted. The maximum outdoor unit is 6HP, and up to 9 indoor air conditioners can be connected. Commonly used in high-end residences, duplex apartments, villas, duplex shops and other places.

　　3. One-to-multiple commercial central air conditioners: There are four types of indoor units: embedded, ducted, floor-mounted, and wall-mounted. The maximum outdoor unit is 48HP, and up to 64 air-conditioning indoor units can be connected. The farthest single pipe is 165 meters long, and the maximum height difference between indoor and outdoor units is 90 meters. Commonly used in office, commercial and residential, catering and other occasions.

　　4, CMS commercial space inverter multi-unit air conditioning system (commercial and office inverter dedicated air conditioning): the maximum air conditioner outdoor unit is 18HP, and up to 15 air conditioner indoor units can be connected. The farthest single pipe is 120 meters long, and the maximum height difference between indoor and outdoor units is 50 meters. Commonly used in office and commercial spaces of 150~5000㎡.

　　VRV air conditioner and fan coil unit inspection key points

　　 The characteristics of VRV and fan coils determine the complexity of the system control, and require very high requirements on pipe material, manufacturing process, and on-site welding.

　　Key points of inspection (air conditioning duct):

　　1. When the outdoor unit is on, an oil-storing elbow must be added for every 10m of the air return pipe, and the height difference between the outdoor unit and the indoor unit should not exceed 50m; (VRV)

　　2. When the outdoor unit is down, the height difference with the indoor unit does not exceed 40m; (VRV)

　　3. The pipe should be supported at intervals of a certain length, and it should not touch the wall and ceiling; (VRV and fan coil)

　　4. The pipeline is insulated with rubber and plastic insulation materials, the thickness of the insulation layer is 20mm, the high temperature resistance is 100℃, and protection should be done when encountering supporting points; (VRV and fan coil)

　　Key points of inspection (outdoor unit)

　　1. Leave 500mm and 300mm or more maintenance space at the front and rear of the outdoor unit; (VRV and fan coil)

　　2. When there is a wall around the outdoor unit, vents should be opened on the wall, and the vents have rainproof function; (VRV and fan coil)

　　3. The obstacle on the top of the outdoor unit must be at least 1500mm away, and the exhaust hood must be installed if it cannot reach it; (VRV and fan coil)

　　4. The foundation should be 100mm～300mm higher than the ground; drainage ditch should be set beside it; (VRV and fan coil)

　　5. The installation of outdoor unit must ensure that the horizontal height difference between the front and back, left and right directions is within 10mm; (VRV and fan coil)

　　 6. The back-to-back installation distance of the outdoor unit must be at least 900mm, and the back-to-side distance z* must be less than 500mm;

　　7. Are there any signs of collision or injury on the surface of the outdoor unit; (VRV and fan coil)

　　Key points of inspection (indoor unit)

　　 1. The indoor unit must be installed in a suitable location to make the indoor temperature distribution balanced; (VRV and fan coil)

　　2. The rear of the indoor unit is slightly lower than the front (0～5mm) to facilitate drainage; (fan coil)

　　3. The connection between the air duct and the indoor unit must be through a canvas hose; (VRV and fan coil)

　　4. There is no air leakage in the air duct, and an adjustment baffle must be added to the diffuser; (VRV and fan coil)

　　 5. The fresh air duct must be connected to the return air box; (VRV and fan coil)

　　6. ​​Set the rotary switch; (VRV and fan coil)

　　The point of inspection (drain pipe)

　　 1. Use polyvinyl chloride pipe (pvc-u); (VRV and fan coil)

　　2, the downward slope of the drain pipe is 10%; (fan coil)

　　3. The drain pipe shall not be connected to the sewage pipe or other drain pipes; (VRV and fan coil)

　　4. The drain pipe needs to be insulated; (VRV and fan coil)

　　5. When the drain pipe is connected to other indoor units, each indoor unit must be higher than the main pipe; (VRV and fan coil)

　　 6. After installation, turn on the power and pour 2.5 liters of water into the drain pan, check that the water is smooth and leak-free, and then pour 2 liters of water when there is no water at the end;

　　 (VRV and fan coil)

　　7. The side of the drain pipe is 5mm lower than other places; (VRV and fan coil)

　　 8. Drain pipe and refrigeration pipe cannot be tied together; (VRV and fan coil)

　　 9. Adhesives cannot be used to connect the drain hose and the indoor unit drain pipe; (VRV and fan coil)

　　Key points of inspection (electrical wiring)

　　 1. One main power supply can be connected to one outdoor unit at most; (VRV and fan coil)

　　2. The power control switch of the outdoor unit must use a leakage protector with rated current ?A and current sensitivity of 100mA; (VRV and fan coil)

　　3. The control system uses shielded twisted-pair cables, the length of which does not exceed 1000m; (VRV and fan coil)

4. Install the wired remote control control line and the unit communication line to keep a distance of more than 300mm from the power line. When the distance is less than 300mm, let the control line (communication line) be arranged in the metal conduit and ensure that the conduit is grounded at one end. Connect the remote control Installed in the iron box; (VRV and fan coil)

　　 5. Do not lay two communication lines together, if necessary, keep a distance of 300mm, or insert each communication line into a metal conduit and ground the metal conduit; (VRV and fan coil)

　　Key points of inspection (trial run)

　　 1. Whether the outdoor unit and indoor unit have abnormal sound and vibration; (VRV and fan coil)

　　2. The current of the outdoor unit is ?A, and the voltage is within ±10%; (VRV and fan coil)

　　3. Is the charge of refrigerant sufficient; (VRV)

　　4. Exhaust superheat: 15～45℃; (VRV)

　　5, suction pressure: 0.2Mpa～1.1Mpa; (VRV)

　　6, exhaust pressure: 1.0MPa～3.5Mpa; (VRV)

　　7. Whether the cooling operation and heating operation can be converted; (VRV)

　　 8. Use a detector to detect refrigerant leakage; (VRV)

　　 9. The temperature difference between the outlet air and return air of the indoor unit is at least 7°C; (VRV)