Temperature-controlling circulating system for moulds - with heat exchanger in line regulated according to line steam pressure

Hollow articles esp. moulds for processing plastics, are heated and/or cooled by a system with circulating heatin/cooling medium, and a heat exchanger to heat the circulating medium and through which cold water also flows by automatic control. The cold water flow is regulated according to the pressure and temp. of the circulating system and is in a pipe-line fitted wiht a pressure reduction valve and a membrane expansion chamber. The membrane is limited to a max temp. of 95 degrees C. With a temp. rise to e.g. 130 degrees C for the heat dissipator the pressure in the circulating system remains below 6 atmos. even if it is controlling a large dissipator. No scaling arises in the cold water. The system is isolated from the water mains. The system pressure is always above the steam pressure at, e.g. 130 degrees C and is thus always operationally effective.