
On a call for heat, a 24 volt signal is applied to the 3-way/2-position solenoid valve. This signal switches th. valve so that compressed air is sent to the pistons. The piston rods extend, pushing the hinged steam dampe. plate to the open position. This allows room air to be drawn through the hot steam coil and then through th. tumbler (basket). When the temperature set point has been reached, the 24 volt signal is removed from the solenoid valve, so tha. the solenoid valve blocks the air suppl