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DocuSign Envelope ID: 9826C043- 4C32- 49CD- A4CC- DC28ABAB7CE7 <br />SECTION 239500 — MULTI - INDOOR VRV SYSTEM <br />F. COMPRESSOR: <br />1. The Daikin inverter scroll compressors shall be variable speed (PVM inverter) controlled <br />which is capable of changing the speed to follow the variations in total cooling and heat- <br />ing load as determined by the suction gas pressure as measured in the condensing unit. <br />a. In addition, samplings of evaporator and condenser temperatures shall be made so <br />that the high /low pressures detected are read every 20 seconds and calculated. With <br />each reading, the compressor capacity (INV frequency) shall be controlled to elimi- <br />nate deviation from target value. <br />1) Non — inverter- driven compressors, which may cause starting motor current to ex- <br />ceed the nominal motor current (RLA) and require larger wire sizing, shall not be <br />allowed. <br />2. The inverter driven compressors in the condensing unit shall be of highly efficient reluc- <br />tance DC (digitally commutating), hermetically sealed scroll "G- type" or "J- type ". <br />3. Neodymium magnets shall be adopted in the rotor construction to yield a higher torque <br />and efficiency in the compressor instead of the normal ferrite magnet type. <br />a. At complete stop of the compressor, the neodymium magnets will position the rotor <br />into the optimum position for a low torque start. <br />4. The capacity control range shall be as low as 3% to 100 %. <br />5. The compressor's motor shall have a cooling system using discharge gas, to avoid sud- <br />den changes in temperature resulting in significant stresses on winding and bearings. <br />6. Each compressor shall be equipped with a crankcase heater, high pressure safety <br />switch, and internal thermal overload protector. <br />7. Oil separators shall be standard with the equipment together with an intelligent oil man- <br />agement system. <br />8. The compressor shall be spring mounted to avoid the transmission of vibration eliminat- <br />ing the standard need for spring insolation. <br />9. In the event of compressor failure, the remaining compressors shall continue to operate <br />and provide heating or cooling as required at a proportionally reduced capacity. The mi- <br />croprocessor and associated controls shall be designed to specifically address this condi- <br />tion for single module and manifolded systems. <br />10. In the case of multiple condenser modules, conjoined operation hours of the compressors <br />shall be balanced by means of the Duty Cycling Function, ensuring sequential starting of <br />each module at each start/stop cycle, completion of oil return, completion of defrost or <br />every 8 hours. When connected to a central control system sequential start is activated <br />for all system on each DIII network. <br />Reece, Noland & McElrath, Inc. 239500-30 Orange County Board of Elections <br />Orange Co., NC 05/04/18 <br />