Corporate Office: 724.584.5500
Instant Access 24/7 (Parts and Service): 800.458.1960
Parts and Service
:
814.437.6861
32
Table 7 – Liquid Line Sizes for R410A (continued)
80 Ton Circuit (R410A)
Total
Equivalent
Length
(ft)
Liquid Line Size (Inch OD)
Horizontal
or
Downflow
Upflow
1 to 5 ft
Upflow
6 to 10 ft
Upflow
11 to 15
ft
25
1⅛
1⅜
1⅜
1⅝
50
1⅛
1⅜
1⅜
1⅝
75
1⅜
1⅜
1⅝
2⅛
100
1⅜
1⅜
1⅝
2⅛
125
1⅜
1⅝
1⅝
2⅛
150
1⅜
1⅝
1⅝
2⅛
175
1⅝
1⅝
2⅛
2⅛
200
1⅝
1⅝
2⅛
2⅛
225
1⅝
1⅝
2⅛
2⅝
250
1⅝
1⅝
2⅛
2⅝
275
1⅝
2⅛
2⅛
2⅝
300
1⅝
2⅛
2⅛
2⅝
Discharge (Hot Gas) Line Sizing
The discharge line sizes depend on the velocity
needed to obtain sufficient oil return. It is very
important to minimize line length and restrictions to
reduce pressure drop and maximize capacity.
Upflow hot gas risers need to have a trap at the
bottom and reverse trap at the top. In addition, a
trap and reverse trap arrangement needs to be
spaced every 15 feet (4.6 m) in the rise for oil
management (see Figure 16).
The discharge lines should pitch downward, in the
direction of the hot gas flow, at the rate of ½ inch
per each 10 foot (1.27 cm per 3.05 m) of horizontal
run. If the chiller unit is below the condenser, loop
the discharge line to at least 1 inch (2.54 cm) above
the top of the condenser. Install a pressure tap valve
at the condenser to facilitate measuring pressure for
service. Take careful consideration in the design of
the discharge gas riser.
Figure 16 – Vertical Riser Traps
All chillers have unloading capabilities. The chiller
uses tandem compressors with one circuit per
tandem set. Unloading will cycle off one of the
compressors. This is not enough to cause problems
with oil return from the remote condenser. Check
the oil-level sight glass in the compressor if there is
a concern there may be oil in the piping.
On chillers equipment with the optional hot gas
bypass capacity control the gas in the upflow
discharge lines may have problems moving the oil
against gravity when completely unloaded. For those
systems only, see Figure 17 and Table 9 for double
riser constructions.
FROM
CHILLER
15'
TO
CONDENSER
TRAP &
REVERSE
TRAP
(4 LR STREET ELS)
REVERSE
TRAP
(3 LR STREET ELS)
REVERSE
TRAP
(3 LR STREET ELS)
VERTICLE UPFLOW
DISCHARGE RISER