Unit installation

CDU Installation Guide Page 37
Cooling Distribution Unit
OPERATION (continued)
6.5 Defer Active Event(s)
When a Warning or Alarm event is generated, volt free relay contacts are also activated within the
controller to give a remote monitoring/extended event facility.
Where these event outputs are utilised by the customer, they can be deferred by a service engineer
(see screen 4-7) for a period of 24, 48 or 72 hours. This means that if an engineer is unable to
immediately rectify a warning or alarm condition when called to site (e.g. a spare part is required), he
can defer the event for a set period to signal that the problem is being addressed, while allowing time
for the spare part to arrive and be installed. Although the extended event will be cancelled, the unit will
remain in warning/alarm condition locally, with the relevant Warning or Alarm LEDs flashing on the
controller fascia and the generated event in the ‘Active’ list until the fault has been rectified.
Any events that have been deferred are identified in the Active list by the prefix ‘deferred’. If after the
set time period the problem has not been rectified, then the extended event will be reinstated.
Similarly, if a new event is generated during the deferred period, then the extended event will again be
re-activated.
6.6 Connection of Additional RDHx’s
If the CDU cabinet has been installed with less than the full capacity of 6 RDHx attached, then additional
RDHx’s can be connected up while the system is operational without the need to shut down.
Sequence to attach additional racks (with optional internal manifolds installed)
1. Ensure the blue plastic cap of the flow balancing valve for the new circuit is screwed
fully clockwise so that the valve is closed.
2. Have enough new deionized water available (pre-treated with inhibitor/biocide) in a
container at the front of the unit to fill the new circuit (refer to Section 3.4 for volume
capacity of RDHx and hoses). Place the filling wand into the container of water.
3. Connect the supply hose of the new RDHx to the supply manifold at the back of the
CDU cabinet, using the quick release coupling provided.
4. Turn the blue plastic cap of the flow balancing valve anti-clockwise approx 1/2 a turn
to crack open the valve and allow water to enter the new circuit.
5. Open air vent points on the RDHx to allow trapped air to escape – check to see if air is
escaping, if not open the valve a little more.
6. As the pressure in the secondary circuit drops, the fill pumps will automatically come
on to top up the system with new fluid.
7. Once all the air has been vented from the RDHx and the fill pumps have stopped, i.e.
pressure at PS1 has been re-established at 0.5Bar (8PSI), then connect the return
hose of the RDHx to the return manifold at the back of the CDU cabinet, using the
quick release coupling provided.
8. The remaining air in the return hose will now be pushed into the CDU cabinet to be
vented via the inbuilt automatic air vent and the fill pumps will start again.
9. Once the fill pumps have stopped, allow system to run for 10 to 15 minutes with this
reduced flow in the new circuit, then fully open the flow/balancing valve to allow the
valve to control to 40L/M (10.6USgpm).