Operating instructions manual [PDF] (20 pages)
- Updated: 25.05.2026
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GAS-FIRED DOUBLE-EFFECT
ABSORPTION CHILLER-HEATER
FOR YOUR SAFETY
If you smell gas:
1. Open windows (only if installed
indoors)
2. Don’t touch electrical switches
3. Extinguish any open flame
4. DO NOT SMOKE!
5. Immediately call your gas supplier
FOR YOUR SAFETY
Do not store or use gasoline or
other flammable vapors and
liquids in the vicinity of this or any
other equipment.
CONTENTS
GENERAL
Page
ABSORPTION PRINCIPLE
2
COOLING OPERATION
3
HEATING OPERATION
4
CONTROLS
GENERAL INFORMATION
5
CONTROL ADJUSTMENTS
8
CONTROL SEQUENCE
12
OPERATION
COOLING
13
PRECAUTIONS
13
HEATING
13
REMOTE CONTROL
13
Page
SAFETY CONTROLS
13
WINTER SHUTDOWN
14
MAINTENANCE
GENERAL INFORMATION
14
MAINTENCE SCHEDULE
14
ROUTINE MAINTENANCE
15
EVACUATION OVERVIEW
15
CHEMICAL MAINTENANCE
17
WINTERIZING
17
TROUBLESHOOTING
17
WATER QUALITY
18
ERROR CODES
19
OPERATING INSTRUCTIONS
CH-MG150
CH-MG200
2
This product is a gas-fired absorption unit which provides
chilled water for cooling or hot water for heating in central
plant-type air conditioning systems. Units with nominal
refrigeration capacities of 150 and 200 tons are complete
with operating and safety controls. The chiller-heater is fitted
with a low NOx burner, automatic spark ignition systems,
power combustion blower and proportional firing control.
When this equipment has been applied correctly,
installed
in
accordance
with
Yazaki
INSTALLATION
INSTRUCTIONS (supplied with the chiller-heater), and with
proper maintenance on the chiller-heater itself and
accompanying support items such as pumps, cooling tower,
etc., it can provide many years of trouble free operation.
GENERAL
These instructions are intended to
acquaint the Owner/End User with the
operation
and
general
maintenance
requirements
of
Yazaki
Gas-Fired
Double-Effect Absorption Chiller-Heater
units.
Please read ALL instructions carefully
and observe precautions. Failure to
operate
and properly
maintain
this
equipment
in
accordance
with
the
OPERATING
INSTRUCTIONS
may
affect the equipment performance and
product Warranty.
If the equipment does not operate as
expected, check the Troubleshooting
Guide in these instructions BEFORE
calling your Yazaki Authorized Service
Provider (ASP). This approach will not
only save cost but also helps to avoid
any unnecessary down time.
THE ABSORPTION PRINCIPLE
Yazaki absorption chiller-heaters use
a solution of lithium bromide and water,
under vacuum, as the working fluid.
Water is the refrigerant and lithium
bromide is the absorbent. During cooling
operation, refrigerant liquid boils under
the influence of a deep vacuum in the
evaporator and creates a refrigerating
effect which removes heat from the
chilled water circuit.
The double-effect absorption cycle
has two generators – one heated by a
gas burner and another heated by
superheated refrigerant vapor. The
resulting refrigerant is passed through to
the condenser, and is then metered into
the evaporator. Lithium bromide solution
leaving the generators flows into the
absorber.
Heat from the cycle is removed by
cooling
water
flowing
inside
the
condenser and absorber tubing bundles.
Heat from the cooling water is rejected
most typically to a cooling tower, but may
also be rejected by alternative methods,
including ground loops.
3
COOLING OPERATION
High-Temperature Generator (HGE)
The gas burner heats a dilute lithium
bromide
solution
in
the
High-
Temperature Generator resulting in a
release of superheated refrigerant vapor.
The
dilute
solution
becomes
more
concentrated
due
to
this
release.
Gravity,
temperature,
and
pressure
differences push the more concentrated
solution through Heat Exchangers to
recycle heat before the concentrated
solution is sent to the Absorber (ABS).
After
release,
the
superheated
refrigerant vapor flows through the Low-
Temperature Generator (LGE) tubing
bundle and is used as the heat source for
the dilute solution that the LGE contains.
Most, if not all, of the refrigerant vapor
will condense into liquid refrigerant
during this process. Ultimately, this
tubing dumps the liquid refrigerant into
the Condenser (COND).
Low-Temperature Generator (LGE)
After
release,
the
superheated
refrigerant vapor heats dilute lithium
bromide solution in the Low-Temperature
Generator.
The
refrigerant
vapor
liberated from this solution flows into the
Condenser while the lithium bromide
solution becomes more concentrated.
Gravity,
temperature,
and
pressure
differences push this more concentrated
solution through Heat Exchangers to
recycle heat before the concentrated
solution is sent to the Absorber.
Condenser (COND)
In the Condenser, refrigerant vapor is
condensed on the outer surface of the
condenser tubing bundle. Latent heat is
removed by the cooling water that flows
inside this tubing bundle. The heat
absorbed by the cooling water is rejected
to a cooling tower or alternative system.
The liquid refrigerant that drips off the
tubing bundle joins the liquid refrigerant
that resulted from the operation of the
LGE and accumulates in the condenser
sump. Liquid refrigerant is routed from
the
condenser
sump
through
an
electronic expansion valve which meters
the liquid refrigerant as required into the
Evaporator (EVA).
Evaporator (EVA)
In the Evaporator, liquid refrigerant is
exposed
to
a
substantially
deeper
vacuum than in the Condenser due to the
influence of the Absorber. As the liquid
refrigerant flows over the surface of the
Evaporator tubing bundle, it boils and
removes heat from the chilled water
flowing inside the Evaporator tubing
bundle. The heat removed from the
chilled water circuit is equal to the latent
heat of the refrigerant, roughly 1000 BTU
per pound of liquid refrigerant boiling into
refrigerant vapor.
Absorber (ABS)
The Evaporator and the Absorber
share the same space. A deep vacuum
in the ABS is maintained by the affinity of
the concentrated solution for refrigerant
vapor. The concentrated solution flows
over the outside of the Absorber tubing
bundle where it is cooled by the cooling
water flowing inside the Absorber tubing
bundle. When the concentrated solution
is cooled, it develops an even greater
affinity for the refrigerant vapor. The
heat absorbed by the cooling water is
rejected to a cooling tower or alternative
system.
The deep level of vacuum in the ABS
section is maintained by the action of the
concentrated
solution
absorbing
the
refrigerant vapor that is being generated
by the EVA during its normal operation.
4
This action dilutes the concentrated
solution back to the same concentration
level as it was when the cycle began.
The dilute solution gathers in the
Absorber sump before being pumped
back into the Generators to start the
cycle anew.
Fig. 1 – DOUBLE-EFFECT ABSORPTION CYCLE (COOLING)
HEATING OPERATION
High-Temperature Generator (HGE)
Dilute lithium bromide solution is heated
in the HGE by the gas burner in the
same manner as in the cooling cycle.
The solution boils vigorously, releasing
superheated
refrigerant
vapor
and
leaving a more concentrated solution.
The refrigerant vapor flows through a
changeover valve into the Evaporator
section. The concentrated solution flows
through another changeover valve into
the Absorber sump.
Low-Temperature Generator (LGE)
Although solution does flow through the
LGE, since the superheated refrigerant
vapor is not flowing in any meaningful
amount through the LGE, the solution
does not release any refrigerant vapor
and the solution simply flows back into
the Absorber sump in essentially a still-
diluted state. The lack of this generator
operation in heating mode is why the
heating capacity is lower than the cooling
capacity in these chiller-heaters.
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