Abstract: One reed of a pair of parallel reeds has a rod extending to opposite sides of the pair. A bimetallic snap disc can be heated to snap against one end of the rod and thus flex the reed to engage a contact on that reed with a contact on the other reed and thus close a circuit to be controlled. A resilient latch holds that reed in its flexed position, even after the disc cools and snaps back to its normal configuration, until a second snap disc is heated and pushes the rod and reed back to its open-contact position. A selectively operable switch serves to provide electric current to a selected one of a pair of resistance heaters, one heater being near each of the snap discs.