What does CRAC unit stand for?

A computer room air conditioning (CRAC) unit is a device that monitors and maintains the temperature, air distribution and humidity in a computer room or data center.

What is a CRAC in HVAC?

A computer room air conditioning (CRAC) unit is a device that monitors and maintains the temperature, air distribution and humidity in a network room or data center. CRAC units are replacing air-conditioning units that were used in the past to cool data centers.

How does CRAC unit work?

CRAC units work just like the air conditioning units in your home. They have a direct expansion system and compressors built right into the unit. They provide cooling by blowing air over a cooling coil filled with refrigerant. The refrigerant maintains its cool state by a compressor within the unit.

What is the difference between CRAC and CRAH units?

Computer Room Air Handler (CRAH) unit, unlike a CRAC unit, uses fans and chilled water coils to remove heat. Because CRAH units do not have compressors, they consume less energy and are more efficient than CRAC units. Typically, chilled water is supplied to the CRAH units from a chilled water supply like a chiller.

What is DX unit in HVAC?

DX stands for direct expansion. In Dx units, air is directly cooled in, at the boundary of, or directly adjacent to the room being conditioned. Heat is directly exchanged with refrigerant passing through a local cooling coil. Refrigerant expands during the process and refrigerant is controlled by an expansion valve.

What does DX mean in HVAC terms?

DX stands for direct expansion cooling. In DX cooling equipment, a refrigerant coil is placed directly in the supply air stream. As the refrigerant evaporates and expands, it removes energy, lowering the temperature of the supply air stream.

What is a VRF unit?

Variable Refrigerant Flow (VRF) systems consist of outdoor units connected to multiple indoor units via refrigerant piping to provide cooling and heating to individual zones.

Is VRF a DX system?

OVERVIEW OF VRF SYSTEMS VRF systems operate on the direct expansion (DX) principle meaning that heat is transferred to or from the space directly by circulating refrigerant to evaporators located near or within the conditioned space.

How much power does a CRAC unit use?

Cooling consumes more than 35% of the 50% power consumption of the auxiliary equipment. Out of this, 15% is consumed solely by the CRAC unit; the remaining 20% by the air distribution system.

How does the CRAC DX precision climate control unit work?

IT CoolingCat. 34, page 427 The CRAC DX precision climate control unit for direct evaporation draws in the warm data centre air from the top of the equipment, cools it in a closed heat exchanger, and blows the cooled air into the raised floor with over- pressure. From there, the air is returned to the data centre via ventilation panels.

What do you need to know about CRAC sizing?

Understanding your legacy system and present requirements is of utmost importance in CRAC unit sizing. You should carry out assessments for leakage, vapor sealing, heat density, and identify obstacles such as pillars and debris before making CRAC unit sizing decisions.

What should the relative humidity of a CRAC unit be?

CRAC units are precision cooling systems, and can precisely control the humidity levels in the data center. Most server vendors allow a relative humidity of 50%, going up to a maximum of 55% RH, and a minimum of 45% RH.