Piping Considerations-Hard-Piped Connections

Piping

5.4Piping Considerations—Hard-Piped Connections

Refrigerant enters and exits the Liebert XDH through connections on the top of the unit (see Figure 16).

The supply piping for each refrigeration circuit is 1/2" OD copper pipe. The return piping for each cir- cuit is 7/8" OD copper. Each Liebert XDH has two supply connections and two return connections, one for each refrigeration circuit.

The Liebert XDH units that are intended for hard-piping connections will have copper caps soldered in place and a holding charge of nitrogen.

Figure 16 Supply and return—hard-piping connections

Top of Liebert XDH	6"
	6"
	(153mm)	3-5/8"	1/2" Supply, Upper
7/8" Return, Upper		(92mm)	1/2" Supply, Upper
		(92mm)	Refrigeration Circuit
			Refrigeration Circuit
Refrigeration
Circuit			1-3/8" (35mm)
			1-3/8" (35mm)
Detail “A”			2-1/8"
			2-1/8"
			(54mm)
			4-1/8"
			(105mm)	5"
Rear of			(127mm)
Rear of
Liebert XDH

7/8" Return, Lower Refrigeration Circuit

Rear of Liebert XDH

1/2" Supply, Lower

Detail "A" Refrigeration Circuit

5.4.1Venting the Holding Charge and Connecting to Mains

After the piping for the supply and return mains has been installed, the Liebert XDH units may be connected. The Liebert XDH is shipped with a low-pressure holding charge (about 30 psi) of nitrogen to prevent oxidation and moisture. Holding charges must be vented from the upper refrigeration circuit and from the lower refrigeration circuit.

To vent the holding charge:

1.Find the four Schrader valves that retain the nitrogen holding charge in the Liebert XDH. The valves are inside the rear door, one on each supply line and one on each return line. Three are near the top of the Liebert XDH; one Schrader valve is in the bottom half of the Liebert XDH.

2.Vent the holding charge in the upper refrigeration circuit by depressing the pin in a Schrader valve on either the supply or return line for that circuit. (The upper circuit’s lines are on the left side of the unit.)

3.Replace and secure the cap on the Schrader valve that was opened.

4.Vent the holding charge in the lower refrigeration circuit by depressing the pin in a Schrader valve on either the supply or return line for that circuit. (The lower circuit’s lines are on the right side of the unit.)

5.Replace and secure the cap on the Schrader valve that was opened.

6.Use a torch to unsweat the caps on unit’s piping connections.

7.Pipe the Liebert XDH’s supply and return connections to the mains. See 5.4.2 - Brazing Preparations for precautions about connecting the Liebert XDH to the piping mains.