Abstract: Apparatus for igniting a solid fuel furnace having a firebox and an electrically controllable fuel supply mechanism for feeding fuel to the firebox comprises an electrically controllable heating element for igniting fuel in the firebox. A control circuit is connected to the fuel supply mechanism and the heating element for energizing the fuel supply mechanism and the heating element for a predetermined activation time and for supplying power to the fuel supply mechanism after the activation time has expired.

Abstract: Controlled environment chamber apparatus for maintaining biological material under controlled conditions of temperature and/or humidity comprises a cabinet defining a chamber, a door for controlling access to the chamber, and a clean air source for providing a flow of clean air past the chamber opening.

Abstract: A control circuit for a forced-air heating system comprises a silicon diode that is positionable in thermally-conductive relationship with the interior space of a furnace plenum. A current source supplies current to the silicon diode, and the potential drop across the silicon diode is sensed. The operating speed of the blower is controlled in response to the voltage drop across the silicon diode in a manner such that when the temperature in the plenum is below a first level, the blower is not driven; when the temperature reaches the first level, the blower is driven at a first speed; and when the temperature reaches a second level, which is higher than the first level, the blower is driven at a second speed, which is higher than the first speed.