Trane Variable Refrigerant Flow System Mini Outdoor Unit Series Manual de Instalação descarregar pdf (Página 31)

VRF-SVN33A-EN 31

Vacuum Drying Procedure

After performing a successful leak test, follow this vacuum drying procedure:

Notes:

• Use tools rated for R-410A.

• Use a vacuum pump that allows vacuuming under 29.7 inH

• Use a vacuum pump with an installed check valve so that pump oil is prevented from

flowing into the pipes when the vacuum pump is stopped.

1. Completely close both the liquid and the gas side service valves.

2. Connect the refrigerant manifold gauge hoses to the liquid side and gas side pipe service ports

and connect the center hose to the vacuum pump.

3. Open both manifold gauge valves and turn on the vacuum pump. With vacuum pressure less

than 29.7 inH

O, allow the vacuum drying to continue for at least 2.5 hours.

Note: More time may be needed depending on pipe length or outdoor temperature.

4. Close both manifold gauge valves to isolate the system. Then quickly shut off the vacuum

pump.

5. Wait 1 hour. Then use the vacuum gauge to verify that the pressure remains at 29.7 inH

O. If

it has, proceed to Step 7.

6. If the pressure increases to over 29.7 inH

O in an hour, either leaks or moisture remain in the

pipes. Repair as necessary using the following procedure:

a. Using a nitrogen gas tank fitted with a pressure regulator, attach hoses from the tank to the

liquid side and gas side service ports on the unit (see location in Figure 20, p. 30).

b. Apply nitrogen at 7.25 psi (0.05 MPa) to help remove moisture in the lines.

c. Perform the vacuum drying procedure again (steps 1–3) for a minimum of 2 hours.

d. Repeat the leak test and the vacuum drying procedure as necessary until the pressure

remains at 29.7 inH

O for 1 hour.

7. Proceed with insulating the pipes (p. 32) and charging the refrigerant (p. 34).

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Trane Variable Refrigerant Flow System Mini Outdoor Unit Series Manual de Instalação Página 31