Single circuit indoor unit for the production of chilled water, with fixed speed and variable speed (Inverter Driven) screw compressors optimized for R513A, electronic expansion valve, high performing shell and tube condenser and shell and tube flooded evaporator, both designed and manufactured by Mitsubishi Electric Hydronics & IT Cooling Systems. The resulting unit is extremely compact, thanks to the strategic layout, designed without base, frame, and panels.