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UAB KOMFOVENT we reserve the right to make changes without prior notice
VERSO STANDARD_21-02
EN
3.6. Connection of a Condensate Drain
Operation of units with counter-flow plate heat exchangers or cooling devices causes condensation, which accumulates
in specially designed condensate trays. Condensate is removed from condensate trays via drainage pipes, therefore a con-
densate drainage system must be connected. Drainage piping must be mounted with a slope, without narrowing sections
or loops preventing water from draining. If such drainage piping is installed outdoors or in unheated premises, it must be
adequately insulated or equipped with a heating cable to prevent water from freezing during winter. Drainage piping is
connected to the unit with a siphon. Due to positive or negative air pressure in the air handling unit, water cannot drain out
of the condensate collection tray by itself. Therefore, it is necessary to connect a proper height siphon or a siphon with a
one-way valve to the drain pipe.
p < 0
p > 0
H mm
H mm
H/2 mm
Ø
15
m
m
Ø
15
m
m
Fig. 13.
Installation of a siphon
Height
H
of a siphon without a one-way valve is selected according to static pressure
p
inside the air handling unit:
H [mm] = 25 + p [mm H
2
O] = 25 + 0.1 x p [Pa]
The height of a siphon with a non-return valve may be lower; however, it depends on the technical data of the siphon
used; therefore, if possible, we recommend choosing its height in the same way as for a siphon without a non-return valve.
Fig. 14.
Example of a siphon with a one-way valve
Any drainage system cannot be directly connected to the common waste water system in order to protect supply air
from contamination with bacteria and odours. Condensate from the air handling unit drainage system shall be collected into
a separate container or should be lead to a sewage grille without any direct contact: do not connect drain directly to sewer
pipe and do not immerse it into water. Condensate collection location must be easily accessible for cleaning and disinfection.
Fig. 15.
Condensate drain connection to sewer system
