HomeVision® Pro
© Corroventa Avfuktning AB
2021.02
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Relative humidity and its impact on materials
All air contains a greater or le
ss amount of moisture but we can’t see it with the naked eye until it
appears in the form of small water drops against a cold surface of metal or glass. However, before it
is visible, moisture is already causing problems by affecting materials and manufacturing processes,
causing corrosion and growth of micro-organisms. In Scandinavia, in particular, one must always
assume that it is humid due to large areas of water in the thousands of lakes and surrounding seas.
Air humidity is measured and is often given in relative humidity (%RH), which is a measure of how
much water the air contains in relation to how much it can maximally contain at a given
temperature. The higher the temperature, the more water the air can hold but it is the relative
humidity which is calculated, and which must be controlled.
At 100% RH the air is saturated and the moisture falls in the form of small water droplets. Steel
corrodes at 60% RH and at 70% RH there is a risk of mould. A rule of thumb is that 50% RH is a good
climate for most materials but here in Scandinavia, it is rarely so low. The annual average value in
most places is instead around 80% RH and can be equally high in both summer and winter.
Controlling humidity
Installing the dehumidifier according to the instructions and manual, provides the conditions for
establishing and maintaining a climate that prevents rot, mould and bad odours in the space.
HomeVision® with its wireless control panel offers easy and convenient monitoring of the climate
from the accommodation and allows the user to select between Fixed RH regulation and MGI
Regulation (mould index regulation).
Fixed RH regulation
With the regulation principle Fixed RH, a setpoint value for the humidity is set, a value to control
around. Furthermore, an upper and a lower hysteresis are set as well as an alarm limit that defines
the alarm level at which, if reached, an alarm appears on the control panel. The chart below is not to
scale, it has the sole purpose of clarifying the principle and parameters.
Alarm level
Setpoint value
Temperature
%-
RH
Dehumidification on
Alarm +%RH
Hysteresis Upper/Lower:
Dehumidification off
