isolation damper (3) is used to isolate the dry side of the Adiabatic unit from the wet side during cold weather operation.
Below freezing damper operation
The isolation damper (3) is completely closed, so that sub freezing air cannot get to the wet media. The bypass damper (2) is completely open, enabling a path for the cold, dry air to enter the IT sections. The outside air damper (1) and hot aisle return damper (4) moderate to maintain a set temperature within the IT sections.
If the humidity within the HP POD 240e NA gets too low, water is added to the media to maintain the low RH humidity parameter, unless the ECS is set to Allow Low RH.
For more information on winterizing the HVAC/ Adiabatic units, see "Preparing the HVAC units for winter." Side view shown
Economizer without additional cooling requirements
