12
A
ir naturally contains a certain amount of water in the form of water vapour and this
determines its humidity level. However, the capacity of air to retain water vapour is limited and
depends on the temperature. The higher the temperature, the greater the quantity of water
vapour the air can retain.
The absolute humidity (A.H.)
value indicates the quantity of water
vapour contained in 1 kg of air and is expressed in grams.
The relative humidity (R.H.)
value
represents the actual quantity of water contained in 1 kg of air expressed as a percentage of
the maximum quantity which can be contained under the same environmental conditions.
In other words, the air in a room at a certain temperature could be considered as a container
with a capacity of, say, 10 litres. If this container were half filled with water, it would be 50% full
(relative humidity) and contain 5 litres of water (absolute humidity). When the container is
completely full, it is described as “saturated”, in other words, there is a relative humidity of
100%, and in this situation water start condensing (e.g. becoming water), creating damages
to walls and furniture.
Experts have established that the optimum relative humidity for our organism and to preserve
furniture and other objects varies between 45% and 60%. Ideally, rooms should therefore be
kept within these values.
A dehumidifier is an appliance that eliminates the excess of moisture on the air (see below).
There is another way to decrease the relative humidity level. It is by increasing the room
temperature. Increasing the temperature is equivalent to increasing the capacity of the
container. When the air is at a temperature of 20˚C, it is the equivalent of a 10 litre container,
while at 30˚C it is the equivalent of a 20 litre container. (see below).
Of course, just increasing the room temperature is not the solution to your excess
moisture/condensation problem. Just warming the air means that you keep the moisture
suspended in the air as vapour, but when the temperature drops, the water vapour forms
condensation again.
However, heating combined with dehumidification (as in the combined mode) especially at
low temperatures- e.g. below 100C, or when drying washing is very useful. It changes
condensation into water vapour , which can then be collected by the dehumidifier, in a fast
an effective way.
Dehumidifiers are the only real answer to controlling condensation and damp in the home.
B r i e f n o t e s o n h u m i d i t y
R.H. = 25%
A.H. = 2.5 l
R.H. = 50%
A.H. = 5 l
R.H. = 25%
A.H. = 5 l
2.5 l of water
eliminated
no water
eliminated
R.H. = 50%
A.H. = 5 l
20°C
5 l
30°C
5 l
20°C
5 l
20°C
2,5 l
DE320GB 28-05-2001 16:58 Pagina 12
