HVAC Guide Specifications
Hermetic Absorption Liquid Chiller
108 to 680 Tons (380 to 2392 kW)
Carrier Model Number:
Part 1 — General
1.01 SYSTEM DESCRIPTION
Microprocessor controlled, single-effect (one-stage) absorption liquid chiller utilizing hermetic
refrigerant and solution pumps, lithium bromide solution as the absorbent, and water as the
refrigerant. Low pressure steam or hot water shall be supplied to the generator as the heat source.
1.02 QUALITY ASSURANCE
A. Chiller performance shall be rated in accordance with ARI Standard 560 (latest edition).
B. Chiller shall be manufactured in accordance with ANSI/ASHRAE 15 (latest edition) Safety Code
for Mechanical Refrigeration.
C. The tube side of the absorber and evaporator sections (when applicable) and the tube side of the
generator (for hot water applications) shall be designed, constructed and stamped in accordance
with ASME Section VIII, Division 1 requirements.
D. Each chiller shall undergo a series of standard factory tests to ensure that the unit is leak tight,
that all electrical components operate as intended, and that every aspect of unit fabrication meets
stringent quality standards in accordance with good practice and the manufacturer’s quality
1. The shell side of each chiller shall be leak tested by pressurizing to 15 psig (103 kPa) with dry
air and then checked by spraying a soap and water mixture on all welds, tube joints, and/or
gasketed joints to identify any major leaks. Afterward, a mass spectrometer test shall be
performed by evacuating the unit to 0.10 mm Hg absolute, covering the machine with a vinyl
tent and introducing helium gas under the tent. Any remaining leaks will allow the helium to be
drawn into the shell side of the machine. The acceptable total leak rate as measured by the
mass spectrometer test shall not exceed .00002 cc/sec standard air.
2. The tube side of the evaporator, absorber, condenser, and (steam) generator shall be
hydrostatically tested at 1.5 times rated design pressure and held for 1 hour. For hot water
applications, a pneumatic test shall be performed on the generator at 1.25 times rated design
3. All machine wiring shall undergo an insulation resistance test. The machine control panel and
all electrical components shall also be functionally tested to verify continuity and proper
4. Final assembly inspection shall consist of verifying that all valves, controls, instrumentation,
pumps, purge components, and all other machine components have been properly installed
on the machine.
5. Each unit shall then be checked for overall appearance and dimensional accuracy.
6. Final inspection shall be performed on each unit to check that painting of the unit is as
specified, nameplate data is correct, and that all accessories are furnished as required.
1.03 DELIVERY, STORAGE, AND HANDLING
A. Unit shall be stored and handled in accordance with the manufacturer’s recommendations.
B. Unit shall not be factory-charged with lithium bromide solution to prevent possible internal
corrosion damage from occurring should the inside of the machine be accidentally exposed to air
during shipment and/or installation. Charging of lithium bromide solution shall be performed at the
jobsite in accordance with the manufacturer’s written instructions.
C. One-piece units shall be shipped under vacuum on the shell side. Two-piece units shall be
shipped with 5 psig (34 kPa) nitrogen pressure.
D. Chiller shall be shipped with nameplates indicating name of manufacturer, model size, serial
number, and all other pertinent machine data.
E. Chiller shall include shipping rails as standard for ease of sliding or moving a unit into position to
simplify installation. Neoprene isolation pads shall also be included with the machine as standard.
Manufacturer shall guarantee the chiller against defects in materials or workmanship for a period of
one year from date of initial operation or 18 months from date of shipment, whichever occurs first.
Manufacturer shall provide the labor to repair or replace any part found to be defective in material or
workmanship within the warranty period.
Part 2 — Products
Absorption liquid chiller shall include evaporator, absorber, condenser, generator, solution heat
exchanger, refrigerant/solution pumps, purge system, piping, wiring, controls and auxiliaries.
Shipment of the machine shall be in 1 or 2 pieces depending on model size. Initial charge of
lithium bromide shall be included with the chiller for charging at the jobsite. Generator shall be
designed for operation on either low pressure steam or hot water as specified on the equipment
schedule. A U-baffle shall be provided in both the upper and lower shell to serve as a natural
insulating barrier between sections. The double sump formed by the U-baffle in the bottom of the
absorber-evaporator section shall allow temporary storage of refrigerant or solution, thereby
reducing service time and expense by alleviating the need to remove the fluids from the machine
during service and/or maintenance operations.
B. Operating Characteristics:
1. Chiller operation shall be characteristic of a single effect absorption cycle. The weak solution
pumped from the absorber to the generator shall initially pass through a solution heat
exchanger to improve operating efficiency by pre-heating the weak solution on the tube side
with the strong solution returning from the generator on the shell side.
2. Unit shall be capable of continuous operation from 100% to 10% capacity, with entering
condenser water temperatures as low as 55 F (12.7 C), without the need for a cooling tower
bypass valve. Thermostat on/off control of the cooling tower fan is recommended when
cooling water temperature falls below 55 F (12.7 C).
C. Heat Exchangers:
1. All heat exchangers shall be of shell and tube construction with shells, tubesheets, tube
support sheets and waterboxes fabricated of carbon steel. All heat exchangers shall
incorporate straight tubes, except for the generator which shall use U-tubes. All tubes shall be
rolled into grooved tubesheets and expanded into tube support sheets, and shall be
2. The evaporator, absorber, and condenser waterboxes shall be designed for 150 psig (1034
kPa) working pressure and shall be supplied with nozzle-in-head (NIH) type waterboxes.
Removable water-box covers shall permit access to all tubes from either end. All waterboxes
shall be provided with vent and drain connections. Nozzle connections shall be of the victaulic
groove type, unless otherwise noted.
3. The generator tube bundle shall consist of U-bend tubes secured to the tube sheet on one
end only to allow for thermal expansion and contraction. The tube side of the generator shall
be designed for 15 psig (103 kPa) working pressure for steam applications; or 250 psig (1725
kPa) working pressure for hot water applications. All hot water generators shall be designed,
constructed and stamped in accordance with ASME Section VIII, Division 1 requirements on
the tube side. For steam applications, a vacuum breaker shall be factory supplied on the
4. A solution heat exchanger shall be an integral part of the machine to increase efficiency by
pre-heating weak solution on the tube side with strong solution on the shell side. Tube
material for this heat exchanger shall be carbon steel.
5. Spray heads for the evaporator, absorber and generator shall be of a non-clogging design,
specifically designed for the intended duty. Spray heads shall be fabricated of a corrosion-
proof material to ensure continuous, high efficiency operation.
6. Heat exchanger tube material and minimum wall thickness shall be contingent on the type of
corrosion inhibitor used in the machine. The following tube specifications shall apply to ensure
long machine life and continuous operation:
Evaporator copper, externally finned
Absorber copper, prime surface
Condenser copper, prime surface
Generator 90/10 CuNi, prime surface
Refrigerant and solution pump/motors shall be self-contained, leakproof, hermetic type, without
pump seals, isolation valves or external seal water system to minimize air leakage into the
machine. Each pump casing shall be welded into suction and discharge lines and factory installed
and shall include spring-loaded, wear-compensating tapered carbon bearings. Lubrication and
cooling shall be accomplished by the fluid being pumped; auxiliary water piping for cooling and
lubrication shall not be acceptable. Pump/motor assemblies shall be designed for 50,000 to
60,000 hours of normal operation between inspections. If pump/motor assemblies are furnished
with less than a design of 50,000 to 60,000 hours between inspections, they must be provided
with isolation valves and a bearing monitoring system to aid in diagnosing and performing on-
E. Purge System:
An automatic motorless purge system shall be furnished to provide a continuous purging action
whenever the chiller is in operation to assure long machine life and efficient performance.
Noncondensables shall be removed from the absorber by a liquid eductor, which shall use flow
from the solution pump to create a suction. Noncondensables shall be stored external to the unit
and shall be prevented from diffusing back into the machine when the unit is not operating.
Evacuation of the external storage chamber shall be accomplished by manually positioning valves
to pressurize the chamber with lithium bromide solution and exhausting it to atmosphere. If the
purge system design is such that it requires a vacuum pump, then it shall be unit mounted and
wired to the control panel by the chiller manufacturer.
F. Controls, Safeties and Diagnostics:
a. The chiller shall be provided with a factory installed and wired microprocessor control
system with individually replaceable modular component construction. The system shall
include a control center, power supply, temperature (thermistor) and pressure
(transducer) sensors, and all necessary auxiliary devices required for proper operation.
The chiller control system shall have the ability to interface and communicate directly to
the building control system without the use of additional field-installed hardware or
software. Additional hardware will be necessary if the building control system is not a
Carrier Comfort Network (CCN).
The control center shall include a 16-line by 40-character liquid crystal display (LCD)
screen, four function keys, stop button, and alarm light. The microprocessor shall be
configurable to display either English or SI metric units.
b. The default standard display screen shall simultaneously indicate the following minimum
date and time of day
24-character primary system status message
24-character secondary system status message
chiller operating hours
entering chilled water temperature
leaving chilled water temperature
evaporator refrigerant temperature
entering absorber water temperature
leaving absorber water temperature
leaving condenser water temperature
strong solution temperature leaving generator
weak solution temperature leaving absorber
output signal to steam/hot water control valve
The default screen shall be displayed if there is no manual activity at the control
console for 15 minutes.
c. The 4 function keys shall be software driven within the Status, Schedule, Set Point and
Service menu structures (as described below).
1) Status Function:
In addition to the default screen, status screens shall be accessible to view the status
of every point monitored by the control center including:
vapor condensate temperature
capacity control valve position
control point settings
refrigerant level switches
solution pump starts
evaporator approach temperature
absorber and condenser approach temperatures
discrete output status of various devices
2) Schedule Function:
The chiller controls shall be configurable for manual or automatic startup and
shutdown. In automatic operation mode, the controls shall be capable of automatically
starting and stopping the chiller according to a stored user programmable occupancy
schedule. The controls shall include built-in provisions for accepting a minimum of
two 365-day occupancy schedules. Each schedule shall allow a minimum of 8
separate occupied and unoccupied periods, any or all of which can be scheduled by
individual day for any or all days of the week, with a separate schedule for holidays.
Schedules shall allow specification of daylight savings start/end and up to 18 user-
defined holidays up to one year in advance (month, day, and duration in days).
Display of the occupancy schedules shall be viewable on the LCD screen. Each
schedule shall provide a means of configuring an occupancy timed override to permit
a ‘‘one time extension’’ of an occupied period on the configured day. The controls
shall also provide for chiller start-up and shutdown via remote contact closure from a
customer supplied device, or from a building management system software
3) Set Point Function:
The controls shall provide the capability to view and change the leaving chilled water
set point, entering chilled water set point, and demand limit set point at any-time
during chiller operating or shutdown periods. The controls shall allow for the
specification of capacity control via either leaving chilled water or entering chilled
4) Service Function:
The controls shall provide a password protected service function which allows
authorized individuals to:
view an alarm history file which shall contain the last 25 alarm and/or alert
messages with time and date stamp. These messages shall be displayed in text
form, not codes.
execute a chiller controls test function for quick identification of malfunctioning
view and/or modify chiller configuration.
view and/or modify chiller occupancy periods.
view and/or modify schedule holiday periods.
view and/or modify schedule override periods.
view and/or modify system time and date.
d. Network Window Function:
Each Chiller LID (Local Interface Device) shall be capable of viewing multiple point values
and statuses from other connected on a common network, including controller
maintenance data. The operator shall be able to alter the remote controller’s set points or
time schedule and to force point values or statuses that are operator forcible. The LID
shall also have access to the alarm history file of all like controllers connected on the
e. Capacity control shall be by means of electronically modulating the steam control valve
actuator to maintain the temperature of the leaving chilled water. Load modulation shall
be from 100% to 10% of machine full load under normal ARI conditions. The steam
control valve shall be precisely positioned by a PID (Proportional Integral Derivative)
control algorithm to ensure precise control (± .5 F [±.3 C]) of desired chilled water
temperature without hunting or overshooting the set point.
f. The microprocessor control system shall include a programmed sequence to ensure
machine readiness prior to machine start-up. The microprocessor shall automatically
activate and interlock the chilled water pump, cooling water pump, cooling tower fans
upon chiller activation.
g. Upon request to start the chiller, the control system shall start the chilled water pump and
verify chilled water flow. The controller shall then compare the entering or leaving chilled
water temperature with the chilled water set point. If the chilled water temperature is less
than the chilled water set point, the control system shall enter the recycle mode until a
cooling load has been established. Once a cooling load has been established the control
system shall start the cooling water pump and verify flow, before starting tower fan(s),
solution pump(s) and refrigerant pump.
Once the refrigerant pump is started the control system shall then initiate a programmed
warm-up cycle. The controller shall then compare the strong solution temperature leaving
the generator and the leaving chilled water temperature. If the high-stage solution
temperature is equal to or greater than 158 F (70 C), and the leaving chilled water is
decreasing in temperature the control system shall enter ramp loading mode. A message
shall be displayed: ‘‘Running Temp Control, Temperature Ramp Loading.’’
h. The control system shall automatically sense impending abnormalities in the absorption
operating cycle and take one or all of the following actions to either self-correct and/or
limit the machine from approaching cycle crystallization line:
inhibit steam control valve position until concentration drops below preset threshold*
drive steam valve to closed position until concentration drops below preset threshold*
initiate non-recycle shutdown of the chiller if safety shutdown threshold exceeded†
*Message will be displayed: ‘‘run capacity limited, high concentration.’’
†Message will be displayed: shutdown in progress, dilution cycle.’’
i. A user-configurable ramp loading rate, effective during the chilled water temperature
pulldown period, shall control the rate of steam control valve opening to limit start-up
steam demand. The controls shall allow configuration of the ramp loading rate in degrees
per minute of chilled water temperature pulldown. During the ramp loading period, a
message shall be displayed informing the operator that the chiller is operating in ramp
j. The control system shall automatically cycle the machine to minimize energy usage
whenever the leaving chilled water temperature is 3 F (1.7 C) below the desired chilled
water set point. The chilled water pump shall remain on, and when the leaving chilled
water temperature rises above the set point by a user-configured amount, the chiller shall
automatically restart. During the shutdown period, a message shall be displayed informing
the operator a recycle restart is pending.
k. The control center shall allow reset of the chilled water temperature set point based on
any one of the following criteria:
Chilled water reset based on an external 4 to 20 mA signal.
Chilled water reset based on a remote temperature (such as outdoor air).
Chilled water reset based on water temperature rise across the evaporator.
When reset is active, a message shall be displayed indicating the type of reset in effect.
l. The control center shall limit the opening of the steam control valve to 50% (user-
configurable) open at start-up until the warm-up period has been completed and ramp
loading is enabled.
m. When the stop button is pressed, or remote contacts open the control center shall
immediately drive the steam control valve to the closed position and initiate the normal
shutdown sequence including dilution cycle. The display shall indicate ‘‘shutdown in
progress, dilution cycle.’’
a. Unit shall automatically shut down when any of the following conditions occur: (Each of
these protective limits shall require manual reset and cause an alarm message to be
displayed on the LCD screen, informing the operator of the shutdown cause.)
solution pump motor overload/high temperature
refrigerant pump motor overload/high temperature
low chilled water temperature
low evaporator refrigerant temperature
generator high solution temperature
loss of evaporator water flow
loss of cooling water flow
prolonged warm-up period
b. The control system shall detect conditions which approach protective limits and take self-
corrective action prior to an alarm occurring. The system shall automatically reduce chiller
capacity when any of the following parameters are outside their normal operating range:
low evaporator refrigerant temperature.
generator high saturation temperature
generator high solution temperature
high solution concentration
During the capacity override period, a pre-alarm (alert) message shall be displayed
informing the operator which condition is causing the capacity override. Once the
condition is again within acceptable limits, the override condition shall terminate and the
chiller shall revert to normal chilled water control. If during either condition the protective
limit is reached, the chiller shall shut down, an alarm shall be generated, and a text
message shall be displayed informing the operator which condition caused the shut down
3. Diagnostics and Service:
a. The control system shall execute a series of pre-start checks whenever a start command
is received to determine if pressures, temperatures, and timers are within prestart limits,
thereby allowing start-up to proceed. If any of the limits are exceeded a text alert
message will be displayed informing the operator of the cause of the pre-start alert.
b. The control system shall provide a manual test which permits selection and test of
individual control components and inputs. A thermistor test and transducer test shall allow
display on the LCD screen of the actual reading of each transducer and each thermistor
installed on the chiller.
A pump test shall automatically energize the chilled water and condenser water pumps,
and the control system shall confirm water flows have been established and require
operator confirmation prior to proceeding to the next test.
A steam control valve test shall allow the operator to test the control valve travel range by
manually increasing or decreasing valve travel limit. Upon completion of the steam control
valve test the control valve shall revert to the closed position.
c. All sensors shall have quick disconnects to allow replacement of the sensor without
replacement of the entire sensor wire.
4. Building Control System Interface:
The chiller control system shall have the ability to interface and communicate directly to the
building control system without the use of additional field installed hardware and software. The
building control system and the absorption chiller must be supplied by the same
manufacturer. If different building control and chiller suppliers are chosen the chiller shall be
supplied with a dataport module which shall translate the information in the chiller
microprocessor to an ASCII stream of data which can be read by any manufacturer’s building
management control system.
G. Electrical Requirements:
1. Power supply to the unit shall be 3-ph, 60 Hz with voltages of 208, 230, 460, or 575 and 3-ph,
50 Hz with 400 v as specified on the equipment schedule. A multitap transformer shall provide
110 v single-phase secondary power for the control panel.
2. Contractor shall supply and install the electrical power line and all auxiliary electrical protection
devices per local code requirements and as indicated necessary by the chiller manufacturer.
3. Contractor shall supply and install electrical wiring and devices required to interface the chiller
controls with the building controls system if applicable.
H. Piping Requirements:
1. Piping and instrumentation for the chilled water, cooling water, steam, and condensate piping
(or hot water supply and return piping) shall be supplied and installed by the contractor/owner.
2. Absorber-condenser crossover piping shall be furnished by the contractor/owner or the chiller
manufacturer as specified on the equipment schedule.
3. Chilled water and condenser water flow switch shall be field installed and supplied by either
the chiller manufacturer or the contractor/owner.
4. Piping from the rupture disk shall be provided and installed by the contractor/owner
and piped in accordance with the chiller manufacturer’s written instructions and any local
I. Thermal Insulation:
Evaporator surfaces shall be factory insulated. Insulation of refrigerant pump, sump, piping, and
chilled water headers, in addition to any hot surfaces shall be field supplied and installed on the
machine. Chiller manufacturer shall recommend the material and specify surface area to be
J. Sound Level:
The overall sound pressure level of the chiller shall not exceed 80 dbA when measured per ARI
Standard 575 (latest edition).
1. Unit manufacturer shall provide a factory-trained service representative, employed by the
chiller manufacturer, to perform and/or supervise chiller pressure test (when required), charge
chiller with refrigerant (water) and lithium bromide solution, place unit into operation, and
calibrate all controls in accordance with the manufacturer’s written start-up, operating, and
2. After unit start-up has been performed, the same factory representative shall be available for
a period of instruction not to exceed 4 hours to instruct the owner’s personnel in the proper
start-up, operating and maintenance procedures.
3. Manufacturer shall provide the following literature:
a. Installation Instructions
b. Start-Up, Operating and Maintenance Instructions
c. Field Wiring Diagrams
L. Options and Accessories:
1. High-Pressure Waterboxes:
Waterboxes rated for 300 psig (2068 kPa) working pressure with removable covers shall be
furnished when specified on the equipment schedule.
2. Hot Water Generator:
A generator designed, built and stamped in accordance with ASME Section VIII, Division 1
requirements with a design working pressure of 250 psig (1724 kPa) shall be furnished for
hot water applications when specified on the equipment schedule.
3. Special Tubing:
Tubing of non-standard materials shall be provided when specified on the equipment
4. CSA Certification:
Chiller shall be certified in accordance with CSA requirements when specified on the
5. Shipping Configuration:
Chiller shall ship in either one or two pieces as specified on the equipment schedule.
6. Flanged Nozzle Connections:
ANSI 150 psig (1034 kPa) R.F. (raised face) flanges shall be furnished on all waterbox
nozzle connections when specified on the equipment schedule.
7. Thermometer Set:
A package of 5 adjustable angle thermometers shall be factory supplied for field installation
when specified on the equipment schedule. Each shall have a 9-in. scale with a working
range of 0° to 120 F (-18 to 49 C) and shall be equipped with a 3/4-in. NPT brass well.
8. Chilled and Condenser Water Flow Switches:
Chilled water and condenser water flow switches, rated for either for 150 psig (1034 kPa) or
300 psig (2068 kPa), shall be factory supplied for field installation when specified on the
9. Steam Valve (electric or pneumatic):
A steam valve shall be provided when specified on the equipment schedule.
10. Unit Voltage:
Unit shall be capable of operating on 3 phase, 50/60 Hz, when specified on equipment
11. Isolation Package:
A vibration isolation package consisting of soleplates and neoprene isolation pads shall be
furnished when specified on the equipment schedule.