Expanding a small-scale, air-cooled IT hardware environment to create a multi-enclosure facility often calls for a new cooling strategy. The first and most fundamental question is whether water-based or refrigerant-based cooling is more appropriate. It also makes sense to understand the total cost of ownership  including both capital expenditure and ongoing operating costs.

Direct expansion (DX) solutions for cooling IT equipment are the quickest and easiest solutions to implement and require less capital expenditure than water-based ones. DX solutions employ conventional refrigerant-based cooling with a split system and a compressor. Cooling is via a closed-loop refrigeration cycle, featuring an evaporator, a compressor, a condenser and an expansion valve.  

Rittal's LCU DX (Liquid Cooling Unit) offers enclosure-based cooling with DX units mounted inside 800 wide IT racks. They are available with up to 6.5 kW output in both single and dual  redunacy variants. The LCU system features horizontal air circulation, supporting the conventional method of front-to-back air flow to the 19-inch racks. Cold air is blown directly in front of the compo-nents . After being warmed by the servers, the air is drawn into the cooling unit at the rear of the enclosure and passes through the heat exchanger, which cools it down. This method requires IT enclosures that are sufficiently air-tight, such as Rittal's TS IT series. Otherwise cold air will escape, impacting overall efficiency. LCU DX units are installable in 800-mm server enclosures.