11
(4) When the drain hose cannot keep a sufficient gradient, it is necessary to fit a riser pipe (field
supplied) to it.
(5) If the air flow of indoor unit is high, this might cause negative pressure and result in return
suction of outdoor air. Therefore, U-type water trap shall be designed on the drainage side
of each indoor unit.
Indoor unit
H
H/
2
Fig.8
(6)
Install water trap as shown below.
(7)
Install one water trap for each unit.
(8)
Installation of water trap shall consider easy cleaning in the future.
Joint
Joint
Indoor unit
Indoor unit
Fig.9
(9)
Connection of drainage branch pipe to the standpipe or horizontal pipe of drainage main
pipe
The horizontal pipe cannot be connected to the vertical pipe at a same height. It can be
connected in a manner as shown below.
NO1:3-way connection of drainage pipe joint.(Fig.10)
NO2: Connection of drain elbow.(Fig.11)
NO3: Connection of horizontal pipe.(Fig.12)
3-way connection
of drainage pipe joint
Connection of drain elbow
Connection of horizontal pipe
Fig.10 Fig.11 Fig.12
