Suction or discharge recirculation is necessary if you do not want to flush the product with a clean lubricant. The shape of the stuffing box can determine the amount of heat being generated. Tapered boxes can cause a rapid rotation of the fluid at the seal faces increasing the amount of heat being generated. The material of construction is another variable. Gaskets do not conduct heat very well.
Product build up on the inside diameter of the stuffing box acts as an insulator.
You need a thermal bushing installed in the end of the stuffing box to isolate the product temperature when you are using a heating or cooling jacket. If not you will trap air, and the faces will run dry. Decide if this is a good idea for your application. The loss of an environmental control can increase the stuffing box temperature. Clean liquid is pumped into the product, diluting it by the amount pumped in.