Gree LHE-S Water-Cooled Screw Chiller

The manual describes LHE-S as a water-cooled screw chiller for air-conditioning systems requiring chilled water; the user provides the cooling-water device on the heat-source side. The manual is intended for startup, operation and maintenance.

In the nomenclature table, LH denotes water-cooled screw chillers; E denotes chiller function, P heat-pump function and I ice-storage function; E in the economizer position denotes an available economizer, while the default is no economizer; suffix -2 denotes a dual-compressor system and Nb denotes R134a. This is a family code convention, not a capacity table.

The manual describes semi-hermetic twin-screw compressors for most water-cooled screw units; a slide-valve mechanism controls capacity over a 25%–100% load range. The evaporator has high-efficiency heat-exchange tubes and a liquid eliminator at the suction inlet; the condenser is a horizontal shell-and-tube heat exchanger integrated with an oil separator.

The LHE-S series uses an electronic expansion valve; temperature and pressure sensors on the compressor discharge line support superheat control, while a stepping motor adjusts refrigerant flow. The control cabinet has strong-current and weak-current sections, with a colour touchscreen for control, status recording, alarm display, total-runtime recording and an external-network interface.

The microcomputer can control from entering or leaving chilled-water temperature, interlock with the chilled-water pump, cooling-water pump and cooling tower, schedule multiple start/stop periods and use password levels. The display shows entering/leaving water temperatures, suction/discharge temperatures, evaporating/condensing pressures, compressor starts, total runtime, set point and historical events; pages can switch between Chinese and English. Listed protections include phase loss, reverse phase, motor overload/overheating, freeze, low flow, high/low pressure, high discharge temperature, sensor error, oil level and safety-valve protection.

The manual’s single-system left-and-right structure table lists the LHE772FE6FEB/Nb row with A=3300, B=1520, C=1620, D=305, E=710, H=345, F=335, G=300, J=410 and K=305 mm; both chilled-water and cooling-water connections are DN150. This is dimensional/connection data from the table, not cooling capacity.

The installation location should avoid corrosive or inflammable substances and smog; location temperature should not exceed 40°C or fall below 0°C, relative humidity should not exceed 90%, and one-hour temperature change should not exceed 8°C. Drainage, tube-pulling space and ventilation for an accidental refrigerant leak are required. The maintenance-clearance table lists for LHE772FE6FEB/Nb: A=600, B=600, C=2800, D=1000 and H=500 mm; no pipes or wiring should be above the unit.

Before piping, cleaning and pressure testing must be completed; pipes must be supported so their weight is not carried by the unit. Inlet and outlet lines generally require flexible connectors, filters, pressure gauges, valves and thermometers; the manual requires a water filter on the unit inlet, with a filter element of at least 20 mesh located as close as possible to the inlet connection. Wiring must be performed by certified electricians after power is cut; copper conductors, protected power cords and reliable grounding are specified.

Before startup, check three-phase voltage, the oil heater, wiring, valves, oil level and signs of refrigerant leakage; inspect the control cabinet with power disconnected. The water system must be cleaned and fitted with filters/Y-filters, valves and suitable instruments; the chilled-water pump, cooling-water pump and cooling tower must be checked. When startup conditions are satisfied, the pump runs before the main motor, which starts about four minutes later (adjustable); automatic compressor loading/unloading maintains chilled-water temperature.

Only qualified personnel should install, operate or maintain the equipment. Do not use oxygen or compressed air to clean or pressurise piping; leak-test with refrigerant or dry nitrogen; do not exceed the allowed pressure and ensure pressure-relief valves are correctly installed and operational before running. Power must be cut and residual voltage ruled out before electrical work; high-voltage devices are for qualified electricians only.

The manual states that R134a is a liquefied refrigerant whose saturation vapour pressure rises with temperature; during shutdown, ambient temperature around the unit should be kept below 45°C or the chilled-water pump should remain on to lower evaporating temperature. A large leak can accumulate R134a vapour near the floor and cause oxygen deficiency; ventilate, circulate near-floor air with a blower and keep out until vapour has dispersed. In an enclosed room, provide effective ventilation, route exhaust piping outside and, where permitted, pipe the safety-valve outlet outside or install an R134a detector.

The manual stresses regular maintenance to preserve normal use and service life; a new unit requires more frequent attention before a regular schedule is adopted. Its maintenance table lists daily start/stop-status checks, weekly water-flow confirmation, quarterly heat-exchanger cleaning and annual safety-valve inspection. For circulating water, the quality table specifies pH 6.5–8.0, conductivity below 800 µS/cm, chloride below 200 mg/L and total hardness below 200 mg CaCO3/L; the manual suggests soft water for the chilled-water circuit.