System information

16
Special knowledge
Radiant cooling, using either the floor or ceiling as an emitter,
will require attention regarding the risk of condensation on the
emitter surface. The C-46 have build in functions for cooling
applications and also allow dew point control with up to 6
wireless relative humidity sensors. When using radiant cooling
it’s strongly recommended to use a dew point control in order
to prevent from condensation.
Emitter surface and humidity
Design temperatures for cooling systems are specified
according to the dew point. The dew point is defined by the
room temperature and the relative humidity. The cooling
capacity of the system is defined by the difference between
the room temperature and mean water temperature.
Often standard design parameters for cooling systems are an
indoor temperature of 26°C and a relative humidity of 50%.
At the dew point the emitter surface will start to condensate.
In order to avoid condensation the emitter surface has to be
over the dew point.
For radiant floor cooling a minimum surface temperature is
defined as 20°C which means that only when the relative
humidity passes 70 % in the room, the risk of condensation
occurs. Because that corresponds to a relative humidity of
100% at the emitter surface.
Radiant cooling from the ceiling is limited by the radiant
asymmetry between the surface of the emitter and the room
temperature. Recommendation is that it should not exceed
more than 14 K. For standard conditions (26ºC, 50% RH) the
surface of the emitter usually reaches the dew point before the
limit.
Distribution pipes and manifolds
In any cooling system where you have distribution pipes or
manifold you have to be aware of that these parts of the
system also have a risk of condensation because it sometime
work below the dew point. Insulation of distribution system is
often necessary to avoid condensation.
Cooling and dew point
Dew point
Design temperature
The design supply water temperature of the system depends
on the type of emitter used, the design indoor conditions
(temperature and relative humidity) and the cooling loads to
be removed. It should be calculated to obtain the maximum
cooling effect possible from the system.
The capacity and mean water temperature for radiant floor
cooling depends on the floor construction, pipe pitch and
surface material. To have the highest possible capacity of
the system you should design your floor construction so the
surface temperature is equal to the minimum temperature of
20°C.
The capacity and mean water temperature for radiant cooling
from the ceiling is calculated, or can be read directly, in the
capacity diagram of the cooling panels. To have the highest
possible capacity of the system you should design as close to
the dew point as possible.
40 45 50 55 60 65 70 75 80 85 90
Dew point temperature
RH%
0
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Room temperature 26°C
Room temperature 25°C
Room temperature 24°C