6
Refrigerant Piping Guidelines
Figure 1
Refrigerant Piping
To ensure the return of oil in the
refrigerant lines, it is necessary to
follow these recommendations:
1. Select the tube lengths with care
and try to avoid having a final few
meters of tube to use up. Refer to
table 2 for tube sizes.
2. Pitch all horizontal suction lines
down towards the unit to assist
gravity oil drainage back to the
compressor.
3. Avoid creating large oil traps in
horizontal suction lines as this will
reduce oil circulating in the system
and may eventually lead to failure
of the compressor.
4. A small oil trap at the end of a
horizontal suction line before a long
vertical riser (of more that 2.5
metres) has the advantage of
assisting the high velocity gas to
carry the oil up the vertical pipe.
5. Liquid lines require no special
installation techniques as the liquid
refrigerant R-22 and the oil mix.
The densities of the refrigerant and
oil are near enough the same so
any movement of liquid refrigerant
will carry oil with it.
6. The installation of a liquid line
sight is recommended. It is very
useful during the maintenance
procedures.
Refrigerant Piping Guidelines
A. Maximum recommended line
lengths: (per circuit)
Maximum linear length 200 Ft.
(W/o accumulator)
Maximum suction line lift 60 Ft.
Maximum liquid line lift 60 Ft.
B. Maximum allowable pressure
drops (R-22):
Suction line 6 psi.
Liquid line 35 psi.
(without subcooler)
Route refrigerant piping for
minimum linear length,
minimum number of bends and
fittings (no reducers) and minimum
amount of line exposed to outdoor
ambients.
C. Recommended line sizes:
TTA075RD (Single Circuit)
TTA150RD (Dual Circuit)
Suction line
1 1/8 inch sealed type L
refrigerant tubing.
Liquid line
1/2 inch sealed type L
refrigerant tubing.
D. Recommended line sizes:
TTA100RD and TTA120RD
(Single Circuit)
TTA180RD, TTA200RD and
TTA240RD
(Dual Circuit)
Suction line
1 3/8 inch sealed type L
refrigerant tubing.
Liquid line
1/2 inch sealed type L
refrigerant tubing.
Stub
Connection
Valve Stem
Valve Cap
Service Valve
Seal Cap
Gauge
Port
Cap
E. Recommended line sizes:
TTA150RD0G, TTA180RD0G,
TTA200RD0G and TTA240RD0G
(Manifolded Compressor)
Suction line
1 5/8 inch sealed type L
refrigerant tubing.
Liquid line
5/8 inch sealed type L
refrigerant tubing.
Note: Insulate all refrigerant piping
and connections.
TTA 150 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8
TTA 180 RD0G 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8
TTA 200 RD0G 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8
TTA 240 RD0G 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8
Table 2 - Recommended Interconnecting Lines
Length of Interconnecting Line (feet)
0-20 21-40 41-60 61-80
Liq. Suct. Liq. Suct. Liq. Suct. Liq. Suct.
TTA 075 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8
TTA 100 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 3/8
TTA 120 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 3/8
Notes: 1. Two line sets are required for dual circuits units.
2. For line lengths over 80 linear feet and 15 feet liquid line riser,
consult your local Trane representative.
TTA 180 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 3/8
TTA 200 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 3/8
TTA 240 RD 1/2 1 1/8 1/2 1 1/8 1/2 1 1/8 1/2 1 3/8
TTA 150 RD0G 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8 5/8 1 5/8
Model
TTA-IOM-EN0110
TTA-IOM-EN0110.indd 6TTA-IOM-EN0110.indd 6 3/19/10 9:20:48 AM3/19/10 9:20:48 AM
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