A compressor assembly includes at least two tandem compressors. Tandem compressors have at least one common suction manifold, communicating a source of working fluid to be compressed by each of at least two compressors, and at least one common discharge manifold communicating a compressed fluid downstream for further use. A common intermediate pressure manifold communicates with intermediate pressure ports in at least two compressors. The intermediate manifold may communicate fluid to or out of the at least two compressors. There is normally no direct communication between suction and discharge manifolds.