38AKS014-024
30GT015-035
Accessory Hot Gas Bypass
50/60 Hz
Installation Instructions
Part No. 30GT911054
Follow all safety codes. Wear safety glasses and work
gloves. Use care in handling equipment.
GENERAL
These installation instructions cover field installation of the
accessory hot gas bypass valve, pilot valve, and hot gas sole-
noid. For 30GT units, these instructions are intended for units
with a starting serial number of 2294F--- or higher. The hot gas
bypass package is not required on 30GT015, 50 Hz units or on
30GT020, 60 Hz units, since these 2 units have hot gas bypass
installed as standard from the factory. See table below for a list-
ing of package contents.
Be sure power to equipment is shut off before performing
maintenance or service functions. Electrical shock may
cause personal injury.
NOTE: Since the 30GT015-035 and 38AKS014-024 units are
single-circuit units, only one accessory package is required per
unit.
INSTALLATION IN 30GT
AIR-COOLED CHILLERS
Step 1 — Install Piping
ACCESSORY PACKAGE CONTENTS
ITEM
Pilot Valve
Hot Gas Solenoid
With Clip
Hot Gas Bypass
Valve
QUANTITY
PART NO.
EF11BS038
1
Shut off all power to the unit and remove refrigerant charge
before continuing with this accessory installation. Failure
to do so may result in personal injury.
1
1
EF19XS024
EA52DC421
See Fig. 1 for a schematic of the unit piping.
5
In addition, the following parts will need to be
field-supplied:
BYPASS LINE — Install the /8 in., field-supplied line
between the factory-supplied stubs in the discharge line (from
the compressor) and in the liquid line between the expansion
valve and cooler. See Fig. 2.
•
•
•
1/4-in. refrigerant grade copper tubing (amount will vary
with application)
3/8-in. refrigerant grade copper tubing (amount will vary
with application)
NOTE: The stubs are sealed as shipped from the factory.
Install the field-supplied shut-off valve in the bypass line as
close to the discharge line as possible. The shut-off valve will
aid in the pumpdown of the low side when closed.
HOT GAS BYPASS VALVE — Install the valve in the bypass
line near the shut-off valve installed in the Bypass Line section
above. The bypass valve has 5/8 in. ODF inlet and outlet (one
each), and a 3/8 in. ODM equalizer port (sweat connection). To
ensure proper operation, the valve should be installed in a hori-
zontal section of the bypass line and the pilot valve should be
installed above bypass valve body.
5/8-in. refrigerant grade copper tubing (amount will vary
with application)
• For 30GT units, one manual shut-off valve for 5/8-in. line
• One 3-way-tee with an internal branch OR one standard
3-way tee (depending on application - see Pilot Valve
and Hot Gas Solenoid section for more information)
• For 38AKS/indoor coil split system, an auxiliary side
connector may be required.
Examine Package Contents — Examine each item
in the package. If any part is damaged or missing, file a claim
immediately with the shipper. See table above for accessory
package contents.
PILOT VALVE AND HOT GAS SOLENOID — Install the
hot gas solenoid onto the pilot valve. The solenoid fits over the
stem of the valve and attaches with the supplied clip on the top
(over the coil).
SAFETY CONSIDERATIONS
Install the pilot valve/solenoid assembly in the external
equalizer line of the bypass valve (3/8 in. ODF equalizer port).
Installing, starting up, and servicing air-conditioning equip-
ment can be hazardous due to system pressures, electrical
components, and equipment location.
Only trained, qualified installers and service technicians
should install, start up, and service this equipment.
When working on air-conditioning equipment, observe pre-
cautions in the literature and on tags, stickers, and labels at-
tached to the equipment.
3
1
The pilot valve has a /8 in. ODF inlet and a /4 in. SAE
(Society of Automotive Engineers, U.S.A.) connection to the
TXV (thermostatic expansion valve) equalizer line.
IMPORTANT: Be sure the sweat connection on the hot gas
bypass valve is facing the pilot valve/solenoid assembly in
the equalizer line (See Fig. 1).
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 533-00067 Printed in U.S.A. Form 30GT/38AKS-1SI Pg 1 1-05 Replaces: 30GT-35SI
Book 1
2
4
Tab 3a 5c 2a
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2. Install a field-supplied 1/4 in. NPT to 1/4 in. flare fitting on
the gage connection port of the compressor suction
service valve.
3. Sweat the pilot solenoid valve supplied in the hot gas ac-
cessory package directly to the hot gas bypass valve on
the 3/8 in. ODF external equalizer port.
INSTALLATION IN 38AKS014-024/INDOOR
FAN COIL (CONSTANT VOLUME)
SPLIT SYSTEM COMBINATION
Step 1 — Install Piping (See Fig. 4)
4. Install field-supplied 1/4 in. copper tube (flared with a nut
on each end) between the compressor suction valve and
the hot gas pilot solenoid valve.
5. Connect a field-supplied 5/8 in. OD copper tube between
the discharge line process tube (hot gas stub) and a field-
supplied manual shutoff service valve, avoiding any traps
in piping.
6. Connect another field-supplied 5/8 in. OD copper tube be-
tween the manual shutoff valve outlet and the hot gas by-
pass valve inlet.
7. Connect a field-supplied 5/8 in. OD copper tube between
the leaving side of the hot gas bypass valve and the Sporlan
auxiliary side connector (distributor-side connector).
Shut off all power to the unit and remove refrigerant charge
using an approved refrigerant recovery device before pro-
ceeding with installation. Failure to do so may result for
personal injury.
IMPORTANT: Do not bury refrigerant piping underground.
1. In applications where the air handler refrigerant distribu-
tor is not equipped with a side outlet connection, it is rec-
ommended that a Sporlan in-line auxiliary side connector
with standard distributor be used. Refer to the installation
instructions for the indoor fan coil to obtain nozzle size
and distributor connection size. Select the auxiliary side
connector based on this information. The side connector
must be installed on refrigerant circuit no. 1 (first stage of
cooling) of the fan coil being used.
LEGEND
TXV
—
Thermostatic Expansion
Valve
*Pilot valve connects directly to
bypass valve per sketch A.
Fig. 4 — 38AKS Hot Gas Bypass Piping
3
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Step 2 — Install Control Wiring (See Fig. 5)
1. Install a field-supplied relay with a 24-v coil and normal-
ly closed contacts rated for 20 va at 125 vac inductive
load. Mount this relay in the 38AKS control box.
NOTE: This relay is identified in Fig. 5 as HGR (hot gas
relay).
2. For 38AKS014-024:
ACCESSORY OPERATION AND
ADJUSTMENT
Adjustment — The hot gas bypass valve is set to begin
opening when the suction pressure falls to approximately
62 psig (427 kPa). The pressure corresponds to a chilled water
set point of approximately 44 F (6 C). If the chilled water set
point is lower than 44 F (6 C), the bypass setting must be de-
creased. The opposite is true if the chilled water setting is
above 44 F (6 C).
a. Connect a field-supplied wire between TB2-3 and
the L1 side of the HGR coil.
Condensing temperature also affects the setting of the bypass
valve, and a change may be required. To adjust the setting of the
bypass valve, a 5/16 in. hex wrench is required. Remove the cap
on the valve, and turn the adjustment nut with the hex wrench.
Turning in a clockwise direction increases the setting, and turn-
ing in a counterclockwise direction decreases the setting.
b. Connect a field-supplied wire between TB2-9 and
the L2 side of the HGR coil.
c. Connect a field-supplied wire between TB2-2 and
HGR-4, one of the normally closed (NC) contacts.
d. Connect one leg of the hot gas pilot solenoid valve
to HGR-6, the other NC contact.
e. Connect the other leg of the hot gas pilot solenoid
valve to C2.
Operation — The hot gas bypass accessory operates as fol-
lows: When a call for cooling is received, the compressor start
circuit is energized, along with the hot gas solenoid (HGS) and
all unloaders. Once the HGS circuit is completed, the solenoid
valve opens allowing the hot gas bypass valve (HGBV) to
sense suction pressure and respond accordingly.
If the suction pressure is below the HGBP (hot gas bypass)
valve setting, the valve begins to open. The valve continues to
open until it either reaches an equilibrium or the maximum
open position. Discharge gas is bypassed into the mixed-phase
line between the expansion valve and the cooler. This condition
continues until the suction pressure rises above the HGBP
valve setting, a second stage of temperature control is called
for, or the unit cycles off.
Step 3 — Restore Refrigerant Charge — Charge
unit in accordance with 38AKS Charging Chart found on unit.
TB2
9
TC2
TB2
3
LLS
HGR
TB2
C2
BLU
YEL
Hot Gas
HGR
Pilot Solenoid Valve
LEGEND
HGR
LLS
TB
—
—
—
—
Hot Gas Relay
Liquid Line Solenoid
Ter minal Block
TC
Thermostat Cooling
NOTE: Hot Gas Relay (HGR) use Part No. HN61KK324.
Fig. 5 — 38AKS014-024 Hot Gas Bypass Wiring
TROUBLESHOOTING
PROBLEM
PROBABLE CAUSE
SOLUTION
Hot Gas Bypass Valve Fails to Open.
1. Dirt or foreign material in valve.
2. Equalizer passageway clogged.
1. Disassemble and clean valve.
2. Disassemble and clean valve.
3. External equalizer not connected or
equalizer line is pinched shut.
3. Connect or replace equalizer line.
Check solenoid valve.
Hot Gas Bypass Valve Fails to Close.
1. Dirt or foreign material in valve.
2. Diaphragm failure.
1. Disassemble and clean valve.
2. Replace element only.
Copyright 2005 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 533-00067 Printed in U.S.A. Form 30GT/38AKS-1SI Pg 4 1-05 Replaces: 30GT-35SI
Book 1
2
4
Tab 3a 5c 2a
Download from Www.Somanuals.com. All Manuals Search And Download.
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