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ManualsBrandsMcQuay ManualsHeat PumpACZ 055A
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Installation, Operation and Maintenance Manual
IOMM ACZ/AGZ
Group: Chiller
Part Number: 074644101
Effective: July 1998
Supersedes: New
© 1997 McQuay International
Liquid Lines
Liquid lines are generally sized for 1 to 2 degree F line losses or their equivalent in pressure drop.
Actual selection can vary based upon the pressure drop expected from refrigerant specialties such as
solenoids, refrigerant driers, valves, etc. piping lifts or risers and the amount of condenser sub-
cooling expected.
The principal concern in sizing and routing liquid lines is assurance that liquid is present in the line
at start-up of the compressor, and that liquid and not vapor is available at the inlet to the expansion
valve during system operation.
Liquid may not be available in a liquid line at start-up if:
1. The solenoid valve is located adjacent to the condenser or condensing unit; remote from the
expansion valve.
2. An excessive length of liquid line is located in a heated ambient and the application permits
migration of the refrigerant to a cold air cooled condenser.
3. Liquid refrigerant is permitted to gravitate from the liquid line to the condenser because of the
relative location of components.
4. Liquid line solenoid valves should be located adjacent to the expansion valve with possibly only
a sight glass interposing the two.
In the event 2) or 3) above are possible, the application should include a check valve at the
condenser end of the liquid line. The check valve should be a low pressure drop valve, and since the
line between the check valve and the solenoid valve can be comparable to a pressure vessel as the
line becomes heated, the check valve should include a pressure relief devise, relieving from the line
LIQUID TO
COIL
EXPANSION VALVE
CONTROL BULB
STRAP TO LINE
AND INSULATE
A
B
DUAL RISER
SUCTION TRAP
SHORT AS
FITTINGS PERMIT
S
U
C
T
I
O
N
P
I
T
C
H
T
O
O
N
E
C
O
M
P
R
E
S
S
O
R
O
N
L
Y
LIQUID TO
COIL
S
U
C
T
I
O
N
P
I
T
C
H
T
O
O
N
E
C
O
M
P
R
E
S
S
O
R
O
N
L
Y
SUCTION TRAP
SHORT AS
FITTINGS PERMIT
EXPANSION VALVE
CONTROL BULBS
STRAP TO LINE
AND INSULATE