10
DEHUMIDIFIER SELECTION –
WHICH PROCEDURE FOR WHICH PURPOSE?
SELECTION FACTOR
ROOM TEMPERATURE
The average air temperature in the room
to be kept dry is the most important deci-
sion criterion for selecting a suitable dehu-
midifier.
High performance below 8 °C
In unheated basements, weekend homes
or cooler rooms with an average room tem-
perature below 8 °C during the wintertime,
we recommend using a desiccant dehumid-
ifier. Their functional principle makes it pos-
sible to keep environments permanently
and eectively dry even at low tempera-
tures.
Even if the temperature occasionally rises
to 12 °C, these devices still work satisfacto-
rily. Above 12 °C, however, their energy
balance becomes worse and using them is
no longer reasonable from an economic
point of view.
All-rounders from 5 to 35 °C
As of an average room temperature of
8 °C, it is generally possible to use refriger-
ant dryers for dehumidification.
If the temperatures permanently drop be-
low 15 °C during the winter months, it is
absolutely necessary to use a device with a
hot gas defrost system.
These all-rounders can be used variably
throughout a very large temperature range,
while using refrigerant dryers with an air cir-
culation defrost system for dehumidification
is only reasonable at average temperatures
above 15 °C – see also figure on page5.
SELECTION FACTOR
OPERATING COSTS
When it comes to the cost-benefit eect
and dehumidification performance in rela-
tion to power consumption, the compres-
sor-operated condenser dryer can very
clearly claim victory in almost all fields of
application.
Peltier condenser dryers, on the other hand,
are less expensive to buy and more energy-
saving at first sight, but they are also char-
acterized by a significantly lower dehumidi-
fication performance and an approx.
400 % higher power consumption for each
litre of condensate that is dehumidified.
The power consumption of desiccant dehu-
midifiers can be up to 100 % higher in di-
rect comparison with compression refriger-
ant dryers. However, the operating costs
rather take a back seat when choosing a
desiccant dehumidifier, since certain appli-
cation requirements can only be realized
using this type of dehumidifier.
SELECTION FACTOR
EFFECTIVE RADIUS
Compressor refrigerant
dryers – great for any room size
The larger the room to be kept dry, the
more favourable becomes the use of a com-
pressor refrigerant dryer. This device group
oers the largest range of dierently
powerful fan/condenser combinations for
private users.
To keep large rooms dry, the dehumidifier
must be supplied with large amounts of
damp air, which requires a powerful fan.
And to dehumidify these air volumes eec-
tively, the device’s condenser must be
equally powerful.
Therefore, when selecting a device, do not
only pay attention to the room size suitability
specified by the manufacturer, but also
check these values for reasonability based
on the air flow rate, power consumption and
dehumidification specifications. A simple
rule of thumb: There is no such thing as
“many litres for only a few watts”, even if this
is something often insinuated by many
providers w.
Peltier dehumidifiers –
specialists for small volumes
Peltier dehumidifiers are no conventional
room air dehumidifiers, for they were not
designed to dehumidify entire rooms but
rather to keep specific areas dry. The com-
pact construction and silent operation pre-
destine this device class to be used in clos-
ets and shoe cabinets, pantries or in some
cases also in small, windowless bathrooms
without much ingress of moisture (no
shower), since Peltier dehumidifiers are on
principle only suited for environments with-
out any additional external moisture ingress
(see “Infiltration” on page11).
Granules
Such desiccants are mainly used to protect
moisture-sensitive goods during transport
and storage. Everyone knows these little
bags that can be found in shipped goods
such as electronic items, handbags, suit-
cases, shoes or medicinal products. Granule
bags are very well suited for keeping such
goods in confined containers dry.
But there are also larger bags combined
with a receptacle available on the market
as “dehumidifiers”. Granules are, however,
unsuitable for this purpose for several rea-
sons.
On the one hand, their eect is limited to
only a few cubic metres of ambient air and
can only be noticed in areas without any
additional external ingress of moisture (see
“Infiltration” on page11).
Furthermore, granule dehumidifiers are
very expensive in relation to their drying
performance since they are a single-use so-
lution requiring the user to regularly buy
new granule bags. Above that, granules
remain silent and simply stop working once
they are saturated with water. No pre-warn-
ing, no “tank full” message, simply no drying
operation w.
Desiccant dehumidifiers –
professional technology for
small, cold rooms
Particularly in cool basements, unheated or
only temporarily heated interior spaces,
there is virtually no alternative to this device
class.
Powerful compressor refrigerant dryers may
also still operate quite eectively in environ-
ments with temperatures of at least 12 °C,
but if the average room temperature con-
stantly lies below 8 °C, desiccant dehumidi-
fiers are able to reach the dehumidification
performance required for dry keeping in a
more ecient way.
