The present invention provides a technique by which heat can be efficiently recovered from a coolant used to cool a reactor, and contamination with dopant impurities from an inner wall of a reactor when polycrystalline silicon is deposited within the reactor can be reduced to produce high-purity polycrystalline silicon. It is shaped similar to a letter S. In this embodiment, the keypad may be mounted behind a small section of the vehicle’s window glass, with command inputs being sensed using electrical, magnetic, or optical detection techniques.