Hot Gas Bypass - Carrier AERO 39MN Installation, Start-Up And Service Instructions Manual

OIL RETURN CONNECTION — If the evaporator coil is
supplied with an oil return connection at the bottom of the
suction header, this small connection must be teed in ahead of
the first mixing elbow and before the TXV bulb as shown in
Fig. 73. The oil return line should be kept small in diameter; a
1 / -in. line will suffice in most cases. It is not necessary, when
4
the compressor is below the evaporator, that the riser at the
evaporator extends at least as high as the top level of the
evaporator; after the 15-diameter riser has been provided, the
suction line may elbow down immediately.
Piping loops serve to control oil accumulation in idle coil
sections and prevent off cycle drain back. When the compres-
sor is located below the evaporator the suction header should
be extended above the highest point of the evaporator circuit
before dropping to the compressor.
EXPANSION VALVE ADJUSTMENT — Each Sporlan TXV
is thoroughly tested and set at the factory before shipment. The
factory superheat setting will be correct and no further adjust-
ment is required for the majority of applications.
How to Determine Superheat Correctly
1. Measure the temperature of the suction line at the bulb
location.
2. Obtain the suction pressure that exists in the suction line
at the bulb location by either of the following methods:
a. If the valve is externally equalized, a gage in the
external equalizer line will indicate the desired
pressure directly and accurately.
b. Read the gage pressure at the suction valve of the
compressor. Add the estimated pressure drop
through the suction line between bulb location and
compressor suction valve to the pressure. The sum
of the gage reading and the estimated pressure drop
will equal the approximate suction line pressure at
the bulb.
3. Convert the pressure obtained in Step 2a or 2b above to
saturated evaporator temperature by using a tempera-
ture-pressure chart.
SPORLAN CARRIER
TYPE PART NO.
ASC-5-4 —
ASC-7-4 EA19BA504
ASC-9-5 EA19BA705
ASC-11-7 EA19BA905
ASC-13-9 —
DIMENSIONS (in.)
SPORLAN
A
TYPE
5 5
ASC-5-4 / ODM /
8
ASC-7-4 7 / ODM 7 /
8
ASC-9-5 1 1 / ODM 1 1 /
8
ASC-11-7 1 3 / ODM 1 3 /
8
ASC-13-9 1 5 / ODM 1 5 /
8
LEGEND
ODF — Outside Diameter, Female
ODM — Outside Diameter, Male
Table 26 — Auxiliary Side Connector (Hot Gas Bypass) Data
CONNECTION SIZES (in.)
Inlet — ODM Solder Outlet — ODF Solder
5 /
8
7
/
8
1
1 /
8
3
1 /
8
1 5 /
8
B C D E
1
ODF 1.88 0.95 1.25 /
8
ODF 2.25 1.06 1.38 1 /
8
ODF 2.81 1.47 1.62 5 /
8
ODF 3.53 1.89 2.19 7 /
8
ODF 3.72 1.83 2.75 1 1 /
8
4. Subtract the two temperatures obtained in Steps 1 and 3
— the difference is superheat.
How to Change the Superheat Setting — The valve should
be set with the system as near as possible to design condi-
tions. To reduce the superheat, turn the adjusting stem coun-
terclockwise. To increase the superheat, turn the adjusting
stem clockwise. When adjusting the valve, make no more
than one turn of the stem at a time and observe the change in
superheat closely to prevent over-shooting the desired setting.
As much as 30 minutes may be required for the new balance
to take place after an adjustment is made.
NOTE: Some valve bodies (G, EG, C, S, EBS and EMC)
have a packing nut around the adjustment stem. It may be
necessary to loosen the packing nut slightly to turn the
adjusting stem. Do not forget to retighten the nut after the
superheat is set.
Hot Gas Bypass —
use of hot gas bypass, hot gas must be introduced between
expansion valve and distributor.
Install auxiliary hot gas bypass side connector (field-sup-
plied) in coil split that is first-on, last-off.
NOTE: See Table 26 for auxiliary side connector sizes. Do
not attempt to use a valve that is smaller or larger than distrib-
utor size. Inserting a bushing at the outlet will defeat the pur-
pose of the internal nozzle tube extension.
Install the side connector as follows:
1. Remove distributor nozzle and retainer ring (area A)
from distributor and reinstall in inlet (area B) of side
connector. See Fig. 74.
2. Solder field-supplied extension nipple to coupling on
distributor, then to side connector outlet, using a silver
solder or equivalent with a melting point of 1300 to
1500 F. Extension nipple should be as short as possible.
3. Solder expansion valve outlet to side connector using
95-5 tin-antimony soft solder, for easy removal.
4. If required, install field-supplied adapter bushing or
coupling to connector inlet before soldering to expan-
sion valve outlet.
Auxiliary — ODF Solder
5 / 1 /
8
7 1
/ /
8
1 5
1 / /
8
3 7
1 / /
8
1 5 / 1 1
8
F
ODF
2
ODF
2
ODF
8
ODF
8
ODF
8
86
When low-load operation requires
USED WITH SPORLAN
DISTRIBUTOR TYPE
1620, 1622
2
1112, 1113
2
1115, 1116
8
1117, 1126
8
/ 1125, 1127, 1143
8
NOZZLE
SIZE
J
G
E
C
A
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