A showerhead electrode assembly for a plasma processing chamber, which includes a showerhead electrode; a heater plate secured to the showerhead electrode; at least one pressure controlled heat pipe secured to an upper surface of the heater plate, the at least one pressure controlled heat pipe having a heat transfer liquid contained therein, and a pressurized gas, which produces a variable internal pressure within the at least one pressure controlled heat pipe; a top plate secured to an upper surface of the at least one heat pipe; and wherein the variable internal pressure within the at least one pressure controlled heat pipe during heating of the showerhead electrode by the heater plate displaces the heat transfer liquid from a thermal path between the top plate and the heater plate, and when removing excess heat from the showerhead electrode returns the heat transfer liquid to the thermal path.