The operation of immersed electrode humidifiers 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).
The quantity of steam produced is proportional to the electric current, which
is in turn proportional to the level of water. This electric current is measured
by a current transformer: by varying the level of water using a fill and drain
electrovalve, the current, and consequently 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 minerals, 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 using the drain solenoid valve and replacing
it with fresh 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
The CAREL solutions for immersed electrode humidifiers are humiSteam and compactSteam.
• AFS system (Anti Foaming System): detects foam
to prevent the release of droplets together with the steam;
• large cylinders with galvanised electrodes and anti-scale filter
on the bottom, for longer maintenance-free operation. Openable and fireproof
cylinders are also available;
• steam production with continuous modulation from 20% to the max.
flowrate (from 10% for the models with two cylinders);
• built-in conductivity sensor and control software to optimise
energy efficiency and operating life, with constant performance over the
life of the cylinder;
• choice between controllers: “Y” (proportional or ON/OFF
from external controller and icon-based display); “X” (modulating
with built-in controller based on pCO technology and alphanumeric and
graphic display with extended messages),“W” (similar to the
“X” controller, however designed for steam baths);
• model “X” manages a second “limit” probe
to reduce production and prevent any condensate forming in the air duct.