Precautions Concerning Piping Connection And Valve Operation - Mitsubishi Electric CITY MULTI PUHY-P-YSMF-B Manuel D'installation

10.3. Precautions concerning piping connection and valve operation

<For variable capacity unit>
• Connect piping and operate valves exactly as described in the figure below.
• After performing the following distributor (gas) connection, remove the con-
necting pipe included with the gas ball valve of the variable capacity unit, and
mount the distributor (gas) (optional).
1 When brazing the distributor (gas), braze it outside of the unit before mount-
ing on the variable capacity unit.
2 During the time when removing the connecting pipe with flange, remove
the seal attached on the back side of this sheet and paste it onto the flange
surface of the ball valve to prevent the entry of dust into the valve.
3 The refrigerant circuit is closed with a round, close-packed packing at the
shipment to prevent gas leak between flanges. As no operation can be
done under this state, be sure replace the packing with the hollow packing
attached at the piping connection.
4 At the mounting of the hollow packing, wipe off dust attached on the flange
sheet surface and the packing. Coat refrigerating machine oil onto both
surfaces of the packing.
• After evacuation and refrigerant charge, ensure that the handle is fully open. If operating with the valve closed, abnormal pressure will be imparted
to the high- or low-pressure side of the refrigerant circuit, or a shortage of oil in the compressor may occur due to lack of oil flow between units, giving
damage to the compressor, four-way valve, etc.
• For evacuating, be sure to provide an oil balance pipe between the variable capacity and constant capacity units.
• Determine the amount of additional refrigerant charge by using the formula, and charge refrigerant additionally through the service port after
completing piping connection work.
• After completing work, shut the service port and cap tightly so that gas leaking does not occur.
Connect ball valve piping in the order of (oil balance) → (liquid side) → (gas side).
•
G
Warning:
Braze the distributor (gas) outside the unit, before mounting distributor (gas)* to ball valve of the variable capacity unit.
- If brazed while mounted, the ball valve is heated and could result in cracking or gas leaks. The wiring inside the unit could also be burned.
16
Ball valve
Ball valve
(liquid side)
(liquid side)
Ball valve
Ball valve
(oil balance side)
(oil balance side)
F
ø15.88
To distributor
To distributor
(liquid)
(liquid)
ø12.7
H
To constant capacity unit
To constant capacity unit
(Figure shows valve fully open.) (Figure shows valve fully open.)
<When shipped from
the manufacturer>
Ball valve
Ball valve
(gas side)
(gas side)
ø28.6
I
J
<After installation>
A
3
1
1
B
A
B
C
D
3
1