US 4,705,936 AGranted

Electronically controlled electric steam humidifier

AssigneeMasco Corporation

InventorJames M. Fowler

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Abstract

An electronic steam humidifier includes a reservoir drawer having boiling electrodes submerged in water provided by a solenoid fill valve energized by a dual reference level current start-up circuit which is responsive to the current flow through the water from an AC source as measured by a current detection circuit. A system operation counter initiates a flush/drain operation after a certain time period of operation to flush mineral deposits from the reservoir through a siphon tube to a drain trough. A current control circuit includes a pulse width modulator connected to a triac for reducing the average current to the boiling electrodes during an overcurrent condition as indicated by a comparator coupled to the current detection circuit. A reservoir interlock mechanism initiates a flush/drain operation when the reservoir drawer assembly is removed for maintenance. A blower control energizes a blower relay so that a furnace or air conditioner blower may be operated to distribute the steam generated by the humidifier.

Claims13

Dependent claims

A steam humidifier comprising a boiling tank, an electronically controlled fill valve for providing water to the boiling tank, a plurality of boiling electrodes disposed within the boiling tank for conducting current from an AC source through the water for generating steam, electrode switching means for selectively connecting an AC source to said boiling electrodes, a current detector for sensing the magnitude of current flowing to the boiling electrodes, an electronic valve control circuit connected to the current detector and the fill valve for actuating the fill valve to automatically replenish water boiled from the boiling tank in response to a decrease in the magnitude of current sensed by the current detector, means for producing a steam operation control signal while the humidifier is operating in a steam generation mode, first timer means coupled to said control signal producing means for accumulating an indication of the total time that said control signal is produced and for generating a first timer output signal indicative of a predetermined accumulated time of operation of the humidifier in a steam generation mode;

said electrode switching means coupled to said first timer means and responsive to said first timer output signal for preventing the flow of current to said boiling electrodes, second timer control means coupled between said first timer means and said fill valve, said second timer control means responsive to said first timer output signal for actuating said fill valve for a predetermined flush time period corresponding to the time required to flush the boiling tank;
and means in communication with said boiling tank and operative during the flush period for draining from said boiling tank water added thereto by said fill valve during said flush period.

A steam humidifier including a boiling tank, an electronically controlled water fill valve for providing water to the boiling tank, a plurality of electrodes disposed within the boiling tank for conducting current from an AC source through the water in the boiling tank for generating steam, means for measuring the level of current flow through said electrodes, and electronic control means responsive to said current level measuring means for cyclically actuating and de-actuating the fill valve to add water to said boiling tank when said measured current is below a desired level, said electronic control means having means for establishing a predetermined initial current level and a predetermined operating current level which is higher than the predetermined initial current level, means for detecting said initial fill cycle, and means responsive to said detected fill cycle for changing the operation of said electronic control means from said predetermined initial current level to said higher predetermined operating current level thereby providing for said electronic control means to operate in an initial fill cycle to de-actuate the fill valve in response to said measured current reaching the predetermined initial current level corresponding to a desired current level for the initial fill cycle and to operate in subsequent fill cycles to de-actuate the fill valve in response to said measured current reaching the predetermined operating current level which is higher than said predetermined initial current level.

Dependencies are inferred from the claim text.