Frequently Asked Questions about
Coolant Distribution Units
Are the CDU common alarm contacts programmable to be NO/NC?
CDUs with firmware rev 1.4 or higher have the option of making the common alarm contacts Normally Open or Normally Closed (NO/NC). Firmware rev 1.3 does not have this option and the contacts are NO.
Does the CDU automatically vary the flow rate to the connected RDHx with changes in heat load?
No, the CDU is designed to provide constant flow to each RDHx. Changes in heat load are addressed by the CDU by modulating the primary valve and allowing more/less primary chilled water to flow to the CDU heat exchanger.
Does the CDU control each RDHx individually?
In order to maximize system robustness and reduce complexity, the CDU controls the water temperature supplied directly to the secondary distribution manifold (internal or external). The CDU has optional flow regulators that can be manually adjusted so that specific high density racks have increased water delivered to them.
Does the CDU have a "Loss of Power" alarm?
There is not a specific alarm for this, but you can get the notification indirectly for the CDU’s with firmware rev 1.4 or higher. The common alarm contacts can be set to Normally Closed (NC) so they are continually energized, if the CDU loses power both contacts will change to Open. This will alert a remote monitor system that there is a problem.
How does the CDU maintain the RDHx supply water above the dew point?
If the facility’s water supply is not within the recommended specifications (see RDHx Planning Guide), a CDU should be utilized. The CDU will create an isolated secondary cooling loop for the RDHx separate from the facility water supply. The CDU monitors the dew point within the room and uses a valve to modulate the heat rejected to the facility water supply. By controlling the valve based on the secondary water temperature the water to the RDHx is maintained in a non-condensing condition.
How long is the CDU temperature/humidity sensor extension cable?
A temperature/humidity sensor ships with each CDU and is mounted at the chassis. A Sensor Extension Cable accessory (20m/65 feet long) is available if a customer wants to remotely mount the temperature/humidity sensor for the floor-mount CDUs.
How many rack-mount CDUs can be controlled off of a single Temperature/Humidity sensor?
Using the Link Cable accessory, up to 6 rack-mount CDUs can be joined together in series. One cable is needed per additional CDU - for 6 CDUs to be controlled from a single sensor, qty 5 Link Cables would be needed.
How many RDHx units can one floor-mount CDU support?
The number of RDHx units supported by a CDU is dependent on the capacity of the CDU as well as the total load within the IT enclosures with RDHx installed. Up to 15 RDHx is possible in many situations, consult with your Coolcentric representative for a configuration suitable for your needs.
How many RDHx units can one rack-mount CDU support?
One rack-mount CDU can support one to two RDHx. If two RDHx will be connected a Hose Splitter accessory will be required to provide the two supply/return lines.
How much control over the floor-mount CDU do you have via Web/SNMP/MODBUS?
Currently SNMP and MODBUS can be used to monitor the CDU only; users cannot alter set points or adjust parameters. When using the Web browser users can adjust set points, etc.
Is it possible to monitor the CDU remotely?
Yes. A gateway is available to support up to 8 floor mounted CDUs and allows monitoring via Web, SNMP and MODBUS. The rack-mounted CDU has an available communications card for connection of 1 CDU to a LON network.
What are the temperature ranges for the supply and return water on the primary side and secondary side of the CDU?
Typical temperature range for the secondary supply water temperature is 12-18°C (54-65°F) with typical return of 18-24°C (64-75°F). Typical primary supply temperatures are in the range of 5-9°C (41-48°F) with return of 13-17°C (55-63°F). Contact Coolcentric to determine actual temperatures based on your site specific conditions.
What is the maximum power consumption of the CDU?
The Floor-mount CDU has a maximum power consumption of 2.5kW when the pump is running at 100%. The Rack-mount CDU has a maximum power consumption of 690W.
What is the volume of the floor-mount CDU reservoir and make-up container?
The reservoir (expansion tank) holds 2.9 US gal (11 liters). The flexible make up container holds 0.5 US gal (2 liters).
What preventative maintenance is required for the CDU?
Coolcentric recommends that you back flush the water filter annually and visually inspect the unit for damage, leaks, etc.
What version of SNMP do we use for the CDU gateway?
Currently SNMPv2 is used.
Where does the CDU have to be situated in relationship to the RDHx it supports?
Physical location of the CDU can vary, we recommend that it is placed within the data center, no more than 40 feet from the RDHx the CDU is supporting. Contact Coolcentric to determine the layout that meets your requirements.
|
