9
EN
Operating manual – dehumidifier / climate manager DH 30 VPR+ / DH 60 VPR+
Here a worst-case scenario:
A modern car wet with rain is parked in a garage along with a
classic vehicle. The room temperature is 4 °C. Attributable to
evaporation of water at the still warm, wet vehicle, the relative
humidity in the garage quickly rises to 95 %.
95 % of relative humidity at
4 °C
mean that in absolute terms
only about
6 g of water
are bound in a cubic metre of air, for
that is the physical limit that can be absorbed.
For comparison:
At a room temperature of
21 °C
and 95 % RH,
17 g of water
are retained by a cubic metre of air. In other words, for every
100 m³ of room air in the garage the air contains over 1 litre
more of pure water (than at 4 °C) in the form of water vapour.
This quickly adds up to several litres of water in the garage! And
it results in the DH-VPR+ withdrawing next to none of the water
from the room air at these low temperatures, because it is
unable to extract any. Hardly any water is bound in the room air,
rendering dehumidification a physical impossibility.
The higher the room temperature, the more moisture
can be absorbed by the room air
Temperature in the
garage:
4 °C
21 °C
Relative humidity:
50 %
95 %
50 %
95 %
Moisture retained
by the room air:
(absolute humidity)
3 g/m³
6 g/m³
9 g/m³ 17 g/m³
Vapour pressure
difference:
3 g/m³
Vapour pressure
difference:
8 g/m³
Consequence for
drying wet
vehicles:
Low drying speed
(minor vapour pressure
difference)
High drying speed
(great vapour pressure
difference)
With 95 % the relative humidity given in our example is rather
high. The vehicle's corrosion and the mould formation at the
walls started immediately. It does not take a great amount of
absolute humidity in the air to get the processes of corrosion
and mould growth going. It is enough if water is bound as
vapour, even though expressed in absolute terms (g/m³) the
values are not very impressive.
And there is another aspect:
Due to the minor absolute vapour pressure differences, the
drops of water on the wet car do not evaporate. It stays wet
despite the DH-VPR+ operation. And the situation is the same:
Low temperatures --> minor differences in the air's moisture
content with regard to the absolute humidity level (g/m³) in spite
of large differences regarding the relative humidity.
Even at low temperatures, the DH-VPR+ keeps the room climate
at the desired level. If new water enters the scene at these low
room temperatures by way of a wet vehicle and the temperature
remains low, the wet vehicle will dry very slowly, hence causing
the humidity inside and at the car to rise to a corrosion-prone
level. Dry keeping is not a problem. Quick drying, however, is a
physical impossibility.
Conclusion:
Using DH-VPR+ devices classic cars can be stored and
showcased during the winter to a temperature of 0 °C. Yet the
capacity is disproportionately reduced (see table
Correlation
between the temperature in the garage and duration of the
drying process
).
However, if both the storage and a quick drying of wet vehicles
are required – also during the winter – you will additionally have
to ensure heating in order to increase the drying rate for wet
vehicles so as to effectively prevent corrosion and mould
growth.
So, if the classic car garage is used all through the year and / or
there are often wet cars inside, we recommend room
temperatures of at least 15 °C. If water only sporadically enters
the garage, there is no need for permanent heating. It will be
sufficient to heat the garage to a level between 15 °C and 20 °C
during the drying phase lasting several days. On these grounds,
we recommend a general on-demand heating option to achieve
a reasonable temperature for drying the garage quickly.
Depending on the temperature, a heating phase of 3 to 7 days
should normally suffice to ensure a fail-safe drying process.
This period can be considerably reduced by the use of fans.
Especially for a quick drying in the car body, at the underbody
as well as in ribbings and hollows we always recommend the
use of fans for wet classic cars (see table
Correlation between
the temperature in the garage and duration of the drying
process
).
The more frequently and extensively the cars are used, the
higher should be the average temperature in the garage so as to
attain a quick and fail-safe drying process and thus to prevent
corrosion and mould.
