A thermal system for rapidly heating and cooling a mold surface of a tool used for forming a composite article, said thermal system comprising and characterised by: I) a heater-subsystem in fluid communication with the tool and comprising; a heater for heating a first thermal fluid, a tank in fluid communication with said heater and containing a mass of heated first thermal fluid, and a three-way valve in fluid communication i) between said tank and said heater for re-circulating the first thermal fluid from said tank to said heater and ii) between said tank and the tool for directing the first thermal fluid from said tank to the tool; II) an exchanger-subsystem in fluid communication with said heater-subsystem and the tool and comprising; an exchanger for cooling the first thermal fluid returning from the tool, and a three-way valve in fluid communication i) between said exchanger and said heater-subsystem for sending the first thermal fluid from the tool back to the heater-subsystem and ii) between said exchanger and the tool for directing the first thermal fluid from the tool to said exchanger; and III) a chiller-subsystem in fluid communication with said exchanger-subsystem and comprising; a chiller to cool a second thermal fluid, a tank in fluid communication with said chiller and containing a mass of cooled second thermal fluid, and a three-way valve in fluid communication i) between said tank and said chiller for re-circulating the second thermal fluid from said tank to said chiller and ii) between said tank and said exchanger-subsystem for directing the second thermal fluid from said tank to said exchanger. I) a heater-subsystem in fluid communication with the tool and comprising; a heater for heating a first thermal fluid, a tank in fluid communication with said heater and containing a mass of heated first thermal fluid, and a three-way valve in fluid communication i) between said tank and said heater for re-circulating the first thermal fluid from said tank to said heater and ii) between said tank and the tool for directing the first thermal fluid from said tank to the tool; II) an exchanger-subsystem in fluid communication with said heater-subsystem and the tool and comprising; an exchanger for cooling the first thermal fluid returning from the tool, and a three-way valve in fluid communication i) between said exchanger and said heater-subsystem for sending the first thermal fluid from the tool back to the heater-subsystem and ii) between said exchanger and the tool for directing the first thermal fluid from the tool to said exchanger; and an exchanger for cooling the first thermal fluid returning from the tool, and a three-way valve in fluid communication i) between said exchanger and said heater-subsystem for sending the first thermal fluid from the tool back to the heater-subsystem and ii) between said exchanger and the tool for directing the first thermal fluid from the tool to said exchanger; and III) a chiller-subsystem in fluid communication with said exchanger-subsystem and comprising; a chiller to cool a second thermal fluid, a tank in fluid communication with said chiller and containing a mass of cooled second thermal fluid, and a three-way valve in fluid communication i) between said tank and said chiller for re-circulating the second thermal fluid from said tank to said chiller and ii) between said tank and said exchanger-subsystem for directing the second thermal fluid from said tank to said exchanger.