25
VTS reserves the right to implement changes without prior notice
Ventus Air Handling Units
Table 6. Types of the supply and drainage connection
AHU size
VS 21 - 55
VS 75 - 650
Humidifier type
Direct drain
Circulating
Supply connection
DN15 threaded
galvanized pipe
High pressure nylon
hose Ø10mm
Drainage connection
DN25 threaded
galvanized pipe
DN25 threaded
galvanized pipe
L/R side versions
no, universal
yes
Table 7. Parameters of humidifier
Parameter
Limit values
Critical air velocity VS21-55
3.0m/s
Critical air velocity VS75-650
4.0m/s
Water temperature
5..40°C
Water pressure
0,15..0,75MPa
Feed water quality
tap water
Ambient temperature for electric cabinet
5..50°C
Ambient humidity for electric cabinet, max
90%rH
Direct drain humidifier is simplified compact construction for limited space in the AHU. Supply water
feeds the humidifying pad from the top and the excessive water falls to the draining pan and goes
directly out of the AHU.
Water supply is controlled by means of solenoid valve installed in the control cabinet (included in the
delivery).
Circulating humidifier relies on the circulating pump which sits in water tank and feeds water to the
humidifying pad. Excessive water falls to the tank and is used again to feed the pad. Due to
evaporation, water level decreases and activates the floating valve, which controls the water supply.
Side effect of evaporation is rising concentration of contaminants in the water tank. To control that
process, two motorized valves operated by control cabinet cut off the water supply and fully drain the
tank. After that the valves switch-over and the humidifier starts operation again with clean water.
Note! For guidelines regarding the water draining, follow the same rules like for drain pans
of the heat exchangers, which are described in the next chapter.
4.10
Draining out condensate
The outlet condensate connections, led outside the AHU's casing are assembled in the drain plates
of glycol, cross-flow and rotary exchangers (the diameter of drain pan connection pipe is 32mm).
Siphons, which are designed to drain out condensed water from the exchangers at different pressure
of the section and environment, should be connected to the drain connections.
For proper drainage of condensate from the unit, the siphon on the drain pan connection pipe must
be installed in the AHU sections, where negative pressure occurs. Drain siphons or siphon parts are
not supplied as standard delivery. There is no need to apply drain siphons in section with
overpressure. In order to minimize air blow-by, you can use a siphon on the system draining out
condensate, assembling the siphon made in accordance with fig.16a and table 8.
Siphons usable „H" height depends on the pressure difference between the AHU section, where
condensate is drained from during operation and the ambient pressure. „H" dimension is provided in
mm and must be higher than the pressure difference expressed in mmH
2
O.
