Abstract: An air conditioner in which an outdoor unit having a compressor, a condenser, and expansion valve and an outdoor fan and an indoor unit having an evaporator and an indoor fan are connected by a piping to form a refrigerating cycle, and which has an outdoor air introducing mechanism including a damper disposed in an air flow path of the indoor fan of the indoor unit so as to enable introduction of outdoor air into the room. The air conditioner has: a comparison means for periodically comparing the room temperature with a room temperature set point; an alteration means for altering, on the basis of the output from the comparison means, a mixed air temperature initial set point preliminarily determined; and a control means for controlling the operations of the outdoor air introduction damper, the outdoor and indoor fans and the compressor.

Abstract: A flame detecting apparatus used in a combustion control apparatus for a water heater provided with a gas burner comprises a pressure switch serving as means for detecting presence or absence of flame and a voltage comparison circuit serving as means for determining the presence or absence of the flame on the basis of the input signal supplied by the pressure switch. The voltage comparison circuit has an offset voltage and has a non-inverting input terminal connected only to the ground.

Abstract: In a digital control circuit, a clock pulse is counted so that when a predetermined timing is reached the driving of a load is controlled. The digital control circuit may preferably be an integrated circuit for controlling the combustion of a burner for a combustion apparatus such as a water heater or an air heater. The combustion control circuit performs the igniting operation for a predetermined period of time and the supply of fuel is stopped if the ignition can not be attained within the predetermined period.

Abstract: A flame-rod type flame detecting apparatus for detecting flames produced intermittently in a pulse-like combustion process is disclosed. An oscillation circuit generates an A.C. flame detecting voltage to be applied across the flame to be detected. The A.C. voltage modulated by the flame provides a signal representative of the presence of flame. The frequency of the A.C. voltage is selected higher than the commercial line frequency and higher than a maximum frequency of the pulse-like intermittent combustion and selected such that the positive half-waves of the applied A.C. voltage are superposed on the flames produced intermittently, and more preferably at least one positive half-wave is superposed on each of the flames.

Abstract: A combustion controlling apparatus is disclosed which is used in a pulse combustion apparatus for generating flames intermittently and which has a flame-rod type flame detector. In this combustion controlling apparatus, a low AC source voltage is converted to a DC voltage and then this DC voltge is converted by an inverter to an AC of about 100 V and 800 Hz which is then supplied to the igniter and flame rod. The inverter comprises a pair of transistors and a transformer having a primary winding with its center tap connected to a DC source voltage and both ends thereof connected to the respective collectors of the transistors which are in turn cross-coupled to the bases of the mating ones through respective series circuits each consisting of a capacitor and a resistor. Thus, in a secondary winding of the transformer, a rectangular wave voltage is produced. The inverter can supply a high voltage to the flame rod during ignition, enabling easy fire detection and can prevent the transistors from generating heat.

Abstract: There is disclosed an igniting and flame detecting device of one rod type having an electrode used for generating a spark for firing gas from a burner and also for supplying an AC voltage for detecting a flame generated by the firing, in which a pulse generating transformer is provided for generating the spark at the electrode with its secondary coil connected in series with the electrode through a discharge tube, a flame detection transformer is provided to apply AC voltage to the flame generated by firing the gas from burner with its secondary coil connected in series with a resistor and a capacitor to form a series circuit which is connected in parallel with the discharge tube, a detection circuit is provided to detect DC voltage component produced, due to rectifying effects of the flame, across the capacitor, and a gap discharge element having a discharge starting voltage which is higher than a normal discharge starting voltage of the discharge tube is connected in parallel with the discharge tube, whereb

Abstract: This invention relates to a control circuit which controls combustion in a burner acting as a heat source of a hot-water boiler or a hot-air heater. More particularly, the present invention relates to a control circuit having a sequence which includes post-discharge such that electric discharge for ignition is still continued for a predetermined period of time, even after attainment of ignition. In a combustion control apparatus, when ignition is not attained within a predetermined safty period, the igniting operation is stopped by a safty timer for timing this safety period, thereby ensuring the safety. It is necessary to reliably discontinue the igniting operatin even when this safety timer is disabled. The present invention attains this object and ensures the safety with a reduced number of timers.

Abstract: An electric corrosion preventing apparatus with a circuit having an indication lamp for indicating an operation state of the apparatus, which is used for preventing an inside wall of a hot-water receptacle, such as a water heater and a boiler, from being corroded by rust. In the circuit, the secondary winding of a voltage-dropping transformer is provided with a couple of diode-capacitor combinations. Those diode-capacitor combinations, respectively, are used for rectifying positive and negative parts of a low AC voltage produced by the secondary winding into positive and negative DC voltages. A positive DC voltage is coupled with an electric corrosion prevention load while a negative DC voltage is coupled with a lamp load. With this circuit arrangement, the positive part of the AC voltage is used for the electric corrosion prevention while the negative part, for the lamp.

Abstract: A timer circuit arrangement for use with a digital combustion control system functions to check failure of a safety timer which stops the combustion operation in the event that ignition is not completed within a predetermined time. The arrangement has a simple circuit which checks the safety timer in advance of initiation thereof. A pre-purge timer, which determines a predetermined time for feeding only combustion air into the combustion chamber for purge thereof in advance of the combustion, and the safety timer are built with a unitary construction. A series connection of flip-flop circuits is provided for carrying out frequency division of clock pulses to obtain predetermined times, and the flip-flop circuits for the safety timer are constituted by at least a part of the flip-flop circuits for the pre-purge timer so that the pre-purge may continue infinitely when the safety timer become out of order, thereby preventing the operation for combustion and ensuring safety of operation.