A cold therapy unit incorporates a cold reservoir containing a cold treatment fluid, typically water with ice and a treatment pad with an inlet line and an outlet line. A thermo-mechanical mixing valve receives treatment fluid from the reservoir and warmer fluid from the pad in a ratio that results in treatment fluid of the desired temperature. A pump delivers that treatment fluid to the inlet line on the pad. A portion of the treatment fluid exiting the pad through an outlet line will return to the reservoir and a portion to the mixing valve as required to maintain a predetermined temperature in the mixing valve.
