What is an electrode steam humidifier?

This technique makes use of the electrical resistance, i.e. the conductivity, of the water. The surface area of the electrodes, the distance between them and the depth to which they are immersed determine the flow of current and thus also the amount of steam produced. To provide the scale-forming substances in the water with as large a surface area as possible (on which they can deposit), large-surface-area grid electrodes are used. The hardness-forming substances crystallise (harden) on these electrodes and act as additional insulators. As the water requires a specific immersion depth of the electrodes, corresponding to the current consumption, for evaporation, the water level in the steam cylinder rises steadily until the available electrode surface area becomes increasingly smaller and, consequently, the steam output decreases. A signal from the humidifier’s electronics indicates that the cylinder is full. Depending on the type of cylinder, this is either replaced with a new one (disposable principle) or reinserted after cleaning the container (for cleanable steam cylinders). To ensure constant readiness for operation even when the unit is at a standstill, the electrodes remain in the water at all times. The adjustable steam output is therefore limited in the lower range, depending on water quality, to 10 to 20% of the steam output capacity. (continuously adjustable 15–100%)

How a steam-air humidifier with electrode heating works

An electrical control pulse switches on the heating current via a contactor. The inlet solenoid valve opens with a delay, allowing water (relative to the steam output) to flow into the steam cylinder from below via the filling cup. The control electronics continuously regulate the inlet and outlet solenoid valves, ensuring that the water quality and conductivity in the steam cylinder remain constant. In technical terms, this is referred to as auto-adaptive adjustment to the available raw water.