A diverter cartridge for a fluid mixing valve includes an inlet adapter having a first inlet port, a second inlet port, a first outlet port and a second outlet port. The cartridge further includes a diverter plate having a first inlet channel and a second inlet channel. The diverter plate is rotatable relative to the inlet adapter between a first end position, a second end position, and a neutral position between the first and second end positions. Rotation of the diverter plate from the neutral position toward the first end position increases a volume flow rate through the cartridge and diverts the fluid to the first outlet port. Rotation of the diverter plate from the neutral position toward the second end position increases a volume flow rate through the cartridge and diverts the fluid to the second outlet port.