A crystal pulling system for growing a monocrystalline ingot from a silicon melt , the system having a pull axis (Y 10 ) and comprising: a housing defining a growth chamber ; a crucible assembly disposed within the growth chamber for containing the silicon melt ; a heat shield that defines a central passage through which an ingot passes during ingot growth; and a cover member that is moveable within the heat shield along the pull axis (Y 10 ), the cover member comprising: a first plate having a first plate axis that is parallel to the pull axis (Y 10 ), the first plate comprising a hub , the hub having a hub opening ; a second plate having a second plate axis that is parallel to the pull axis (Y 10 ), the second plate being disposed above the first plate, the first plate and second plate forming a cover member chamber ; an insulation layer being disposed between the first plate and the second plate and contacting the first plate and the second plate, the insulation layer being made of felt, the insulation layer being disposed within the cover member chamber; and a shaft having an elongated portion and a collar that extends radially outward from the elongated portion , the shaft extending through the hub opening , the first plate resting on the collar. a housing defining a growth chamber ; a crucible assembly disposed within the growth chamber for containing the silicon melt ; a heat shield that defines a central passage through which an ingot passes during ingot growth; and a cover member that is moveable within the heat shield along the pull axis (Y 10 ), the cover member comprising: a first plate having a first plate axis that is parallel to the pull axis (Y 10 ), the first plate comprising a hub , the hub having a hub opening ; a second plate having a second plate axis that is parallel to the pull axis (Y 10 ), the second plate being disposed above the first plate, the first plate and second plate forming a cover member chamber ; an insulation layer being disposed between the first plate and the second plate and contacting the first plate and the second plate, the insulation layer being made of felt, the insulation layer being disposed within the cover member chamber; and a shaft having an elongated portion and a collar that extends radially outward from the elongated portion , the shaft extending through the hub opening , the first plate resting on the collar. a first plate having a first plate axis that is parallel to the pull axis (Y 10 ), the first plate comprising a hub , the hub having a hub opening ; a second plate having a second plate axis that is parallel to the pull axis (Y 10 ), the second plate being disposed above the first plate, the first plate and second plate forming a cover member chamber ; an insulation layer being disposed between the first plate and the second plate and contacting the first plate and the second plate, the insulation layer being made of felt, the insulation layer being disposed within the cover member chamber; and a shaft having an elongated portion and a collar that extends radially outward from the elongated portion , the shaft extending through the hub opening , the first plate resting on the collar. <EOS>