A temp. controlling device for the barrel with nozzle on plastics processing equipment has outer metal jackets with inner contact surface and concentric exterior; these jackets are held tightly against the surface to be controlled using straps; two such jackets are used in each case and they contain thermal elements in the form of tubes; they each have at least one loop with two straight arms and one curved part, the loop being disposed symmetrically about a longitudinal line along the barrel. A single temp. control element is embedded in each jacket and has areas free of the embedding cast metal, where there are holes from the inner and outer surfaces of the jackets.
