The operation of the immersed
electrode humidifier is based on a
very simple physical principle. As
common drinking water contains a
certain quantity of dissolved mineral
salts, and is consequently slightly
conductive, applying a voltage to
metal electrodes immersed in the
water creates an electric current
that heats the water until producing
steam (Joule effect).
This electric current – proportional at
any instant to the amount of steam
produced – is measured by a current transformer. By varying the level of water (and therefore the immersed portion of the electrodes) using a fill and drain electrovalve, the steam production can be precisely modulated. Due to evaporation, the level of water decreases and must therefore be topped up; as the steam does not carry the mineral salts, the salt concentration in the water and therefore the conductivity increases, meaning that the water has to be periodically diluted by draining part of it and replacing it with new water.
In addition, lime scale is deposited over time and covers part of the cylinder, which must be replaced or cleaned.
The principle is simple, however the development of an immersed electrode humidifier that ensures safe operation and reliability over time requires careful analysis and extended testing.
Compared to the complementary immersed element heater or gas humidifiers, immersed electrode humidifiers:
• are less expensive to purchase;
• operate with drinking water
(not completely demineralised or softened);
• require the periodical replacement
(or cleaning) of the cylinder;
• feature modulation suitable for comfort
or industrial applications, without extreme requirements.

CAREL has been manufacturing immersed electrode humidifiers since the 1970s and can draw benefit from its know-how in the field of electronic controllers: precision control, reliable electronics and sophisticated and complete control software.

CAREL solutions for the immersed electrode humidifiers are humiSteam and homeSteam.