Unit installation

CDU Installation Guide Page 40
Cooling Distribution Unit
MAINTENANCE (continued)
If flushing the filter does not improve conditions, then the filter screen should be replaced.
For the primary circuit, this will mean isolating the cabinet from the chilled water supply by closing the
1½” ball valves at the rear of the cabinet (see Section 5.2), then draining the filter with the drain hose
as used for the flushing procedure. Once drained the filter bowl may be unscrewed and the filter
screen removed & replaced. Re-fit the filter bowl, close the filter drain valve and open the chilled water
ball valves again.
7.6 Unit Draining
There are three drain points provided at the front of the unit as shown in Fig. 9.
To drain the primary circuit, first close off both the primary inlet & primary outlet isolation ball valves at
the rear of the cabinet (see Fig. 4). Place a suitable collection vessel under the drain pipe and open
the drain valve. Note: to assist draining the manual air bleed valve situated on top of the pipe at the
primary entry to the plate heat exchanger (see inset photo below). To operate this vent, unscrew the
brass cap and depress the visible spindle. The primary filter should also be drained as for filter flushing
(see Section 7.5).
To drain the secondary circuit, both of the other two drain valves should be used, air will bleed into the
system through the automatic air vents. If the unit is to be removed altogether, the RDHx hoses should
first be disconnected, then the inlet & return manifolds also drained by manually depressing the self
sealing valves within the quick release couplings.
If sufficient drainage is only required for changing a pump, the faulty pump should first be isolated with
the red handled valves, then the drain valve opened associated with that pump only. Note: To fully
drain the pump prior to removal, also remove the drain plug at the base of the pump (indicated below)
– be prepared for a few cupfuls of water to be discharged.
Fig. 9 – Drain Points
Primary circuit drain
Secondary circuit drain
Secondary circuit drain
Pump drain
plug location
Drip tray sump drain
(located under cabinet
floor)