Planning for the installation of rear door heat exchangers

Planning considerations overview

As you plan the installation of the heat exchanger, include the following considerations:

• Providing chilled, conditioned water that meets the specifications that are outlined in Water control and conditioning of the secondary cooling loop.
• Procuring and installing the water supply system that is suitable for your data center. Details are provided in Water delivery specifications for secondary loops.
• Providing redundant secondary cooling loop water supply, or enough room air conditioning to handle a tolerable heat load if the function of one or more of the heat exchangers is compromised. If the rear door is opened for rack maintenance, or conditioned water supply to the door is stopped, the rack heat load is sent out into the room and must be handled by room air conditioning. This will occur until the conditioned water supply is restored.
• Providing floor or ceiling tile cutouts or protective coverings to avoid tripping hazards on non-raised floors as part of hose management.

Water control and conditioning of the secondary cooling loop

It is very important that the water that is being supplied to the heat exchanger meet the requirements that are described in this section. Otherwise, system failures might occur over time, as a result of any of the following problems:

• Leaks due to corrosion and pitting of the metal components of the heat exchanger or the water-supply system.
• Buildup of scale deposits inside the heat exchanger, which can cause the following problems:
  • A reduction of the ability of the heat exchanger to cool the air that is exhausted from the rack.
  • Failure of mechanical hardware, such as a hose quick-connect coupling.
• Organic contamination, such as bacteria, fungi, or algae. This contamination can cause the same problems as described for scale deposits. The water that is used to fill, refill, and supply the heat exchanger must be particle-free deionized water or particle-free distilled water with appropriate controls for avoiding these issues
  • Metal corrosion
  • Bacterial fouling
  • Scaling

The water cannot originate from the primary chilled-water system for the building but must be supplied as part of a secondary, closed-loop system.

Water delivery specifications for secondary loops

This section describes the various hardware components that make up the delivery system secondary loop that provides the chilled, conditioned water to the heat exchanger. The delivery system includes pipes, hoses, and the required connection hardware to connect to the heat exchanger. Hose management in raised floor or non-raised-floor environments is also described.

The primary cooling loop is considered to be the building chilled-water supply or a modular chiller unit. The primary loop must not be used as a direct source of coolant for the heat exchanger for the following reasons:

• If the supply water temperature is below the room dew point, condensation forms and causes dripping from the door components.
• If a leak develops in the door, supply hose, or return hose, a large amount of water is available.

Procurement and installation of the components that are needed to create the secondary cooling loop system are required for this design and are your responsibility. See Secondary cooling loop parts and services information for information about suppliers of hoses and cooling distribution units.