Download Heto CB8-30 Service Manual

Service Manual
HETO CBN 8-30, 18-30 & 28-30
SERVICE MANUAL
HETO CBN 8-30, 18-30 & 28-30
-30 °C Cooling Baths
ID: 88872216
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SERVICE MANUAL
Cooling Bath
This document consists of two manuals:
The Instruction Manual
which is meant for the operator of the HETO CBN 8-30, 18-30 & 28-30 -30°C
COOLING BATHS
The Service Manual
which contains additional information to assist
in performing service on the HETO CBN 8-30, 18-30 & 28-30 -30°C COOLING BATHS
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Contents
1.
2.
3.
4.
5.
6.
Page:
Introduction to the Service Manual..................................................... 2
Safety Precautions ................................................................................. 2
General Description .............................................................................. 3
Overview ................................................................................................. 3
Trouble Shooting ................................................................................... 6
Servicing a Refrigeration System ........................................................ 7
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
Introduction..................................................................................................................... 7
Servicing systems ........................................................................................................... 7
Equipment for refrigeration servicing ............................................................................ 8
Compressor diagnostics procedure ................................................................................. 8
Leak detection ................................................................................................................. 9
Moisture in the refrigerant .............................................................................................. 9
Charging the system........................................................................................................ 9
Charging Procedure ...................................................................................................... 10
7. Technical Data ..................................................................................... 10
8. Electrical Diagrams ............................................................................. 11
8.1
8.2
Wiring Diagram ............................................................................................................ 11
Compressor diagram ..................................................................................................... 11
9. Cooling Diagram.................................................................................. 12
10. Spare parts ........................................................................................ 12
Information about this manual:
Document Number
367600
Replaces Document
-
Remarks
New Manual
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Cooling Bath
1. Introduction to the Service Manual
This manual describes service, trouble shooting and repair of the Heto Cooling baths type
CBN 8-30, CBN 18-30 and CBN 28-30,
with an operating range from -30°C to +100°C continuously and up to +120°C for shorter periods,
using appropriate liquids to maintain a good temperature stability.
The manual is intended for engineers, who is educated in the basic principles of compressor cooling
systems, and who have experience in servicing such systems.
For installation, use and maintenance of the Heto Cooling baths, see the instruction manual.
The Heto CBN -30 series Cooling baths are high performance units. They combine the demand for
high cooling power with low ultimate temperatures. The cooling baths have been specially designed
to work together with the Heto HMT series thermostats, but can also be used together with previous
Heto thermostats and other manufacturers products.
2. Safety Precautions
The cooling baths are designed according to EN61010. This assumes that two separate faults do not
occur simultaneously. The cooling bath therefore offers protection against a single fault.
Warning: Fire hazard
A potential fire hazard exists when operating the bath with flammable fluids at temperatures above
their respective flash point. Fluids with flash points below ambient temperature are particularly
hazardous.
When installing a thermostat with the cooling bath, ensure that the excess temperature protection is
set not higher than 5°C below the flash point / boiling temperature of the liquid. See separate
instruction manual for the thermostat.
Warning: Electrical shock
When removing the cover plates, electrical connections are uncovered. Never work inside the
cabinet without disconnecting the Mains cable.
The cooling bath must never work in ambient temperatures lower than +5°C and higher than +32°C.
The cabinet has openings for air circulation. The openings must never be covered and there must
always be sufficient room for air circulation around the cabinet (minimum 100 mm).
Since the unit is capable of achieving temperatures down to -30°C, precautions should be taken to
avoid freezing of the liquid which could damage the circulation pump on the thermostat.
Use HETO-HOLTEN A/S recommended liquids as stated in the instruction manual in order to assure
maximum performance and avoid unnecessary problems.
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3. General Description
The Cooling baths are based on a single compressor cooling system, with capillary tubes to combine
high cooling power with the ability to reach low temperatures.
The Cooling baths uses the refrigerant R134a that is a CFC and HCFC free refrigerant with an
evaporating temperature of -26.5°C at 1 bar abs pressure.
4. Overview
Mains switch
Drain hose
Opening for air circulation (must never be covered)
Fig. 1 Front view
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Remove the 3 screws under the plate
Pull the cover plate gently down
Remove the grounding wire on the rear
side of the plate
Fig. 2 Removing the cover plates
3 screws
Drain hose
Filter dryers
Fig. 3 Left view
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Fan motor
Start capacitor
Start relay
Compressor
Fig. 4 Right view
Identification label
Air outlet (must never be covered)
Fuses
Mains connection
Fig. 5 Rear view
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5. Trouble Shooting
Prior to performing this procedure make sure that no thermostat is connected to the Cryo bath.
Problem
Cause
Cooling system does not. Mains not connected.
Start
Mains cable defective.
Mains switch defective.
Fuses blown.
Internal wires defective.
Compressor blocked.
Compressor coils
defective.
Start capacitor or start
relay on compressor is
defective.
Cooling system starts, but Condenser is blocked.
cooling power is poor.
Fan is defective.
Refrigerant leakage.
Cooling system starts, but Capillary tube blocked.
no cooling appears.
Cylinder head gasket
blown.
Refrigerant lost.
Indication
Action
No light in Mains switch. Reconnect Mains.
Replace Mains cable.
Replace Mains switch.
Replace fuses.
Replace defective wire(s)
Locked rotor current
Evacuate system.
=17.5 A.
Replace Compressor.
Resistance in windings
Recharge system.
out of range. See table of
resistance in section 7.
No faults on the above.
Replace start relay and
start capacitor.
Refrigerant discharge
temperature from
condenser > 60°C.
Fan is not rotating
Equalisation pressure
< 10 bar abs.
Pressure rises on the high
pressure side.
Compressor unable to
create pressure difference
between suction and high
pressure line.
Equalisation pressure  1
bar abs.
Clean condenser with
compressed air.
Replace fan.
Find leak.
Recharge system.
Replace the filter dryer..
Evacuate system.
Replace Compressor.
Recharge system.
Find leak, recharge
cooling system.
For electrical and cooling diagram for Cooling bath and compressor unit see sections 8 and 9.
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6. Servicing a Refrigeration System
6.1 Introduction
The service technician attempting to repair a refrigeration system must have experience in and have
a thorough understanding of the fundamentals of mechanical refrigeration. He should have previous
experience in servicing household as well as commercial refrigeration equipment.
A general knowledge of electrical controls is also necessary.
When servicing a refrigeration system the following precautions and procedures must be observed:
Leak detection:
If soap bubbles do not detect the leak, the system must be thoroughly leak tested by conventional
means or pressure tested with N2 at 20 bar.
Evacuation:
Refrigerant must always be evacuated from the system due to environmental regulations.
Brazing:
If brazing is required on the system, a thorough evacuation is absolutely necessary to remove all
refrigerant; the vacuum must then be replaced with dry nitrogen.
Charging:
A refrigerant supply from cylinders should be routed to the system through a new or dry dryer.
6.2 Servicing systems
In the event of failure, every effort must be made to make certain that the problem is not electrically
caused prior to attaching gauges or opening the refrigeration circuit.
Before starting repairs of any system locate the placement of the components. See sections 3 and 4.
By following the piping and, at the same time, referring to section 9 the parts may be located.
Some parts must be well insulated, and these components are therefore made of silver brazed copper
with no moving parts; they rarely, if ever require servicing. It is recommended that these parts are
not uncovered unless necessary.
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6.3 Equipment for refrigeration servicing
In addition to the normal hand tools generally required (wrenches, screw drivers etc.), it is necessary
to have the following tools available :






Silver brazing equipment.
Tank of dry nitrogen equipped with pressure regulator.
Vacuum pump capable of reducing pressure to 1 hPa (1000 microns ).
Mercury manometer to read pressure to 1 hPa.
Electronic leak detector.
Charging and testing manifolds.
The following is required for servicing the cooling bath:




Refrigerant R 134a.
Spare compressor.
Drying filter.
Fan motor.
6.4 Compressor diagnostics procedure
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Check the compressor relays, overloads and capacitors.
Check the temperature control contacts, contact and associated wiring.
Measure voltage at the compressors.
Check the line voltage at the compressors and check low line voltage is a frequent problem in
many areas.
Clean the air cooled condenser.
Be sure that the cabinet is located so that the free flow of air through the condenser is not
obstructed. Fans should turn freely and run at full speed when energised.
When attaching service gauges to, or when opening any part, every effort should be made to
keep the system clean and dry.
Gauges and hoses should be well purged with the same refrigerant and leak tested before access
valves are opened.
On start-up, as the cooling system "comes alive", heat should appear at the condenser as the
suction pressure rises. A cold spot should appear inside the bath as refrigerant is fed to the
evaporator. With continued operation bath should continue to cool until the design temperature
is reached.
After a short period the suction and discharge pressures will increase until normal pull down
loading is achieved.
Refrigerant leaks, moisture and component failure can be diagnosed in much the same way as in
other refrigeration equipment.
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6.5 Leak detection
An electronic leak detector can be used in the compressor compartment. If problems are
encountered in pinpointing a leak, soap bubble testing will help. A safe method of leak testing the
entire system is to pressurise to 20 bar using N2 and with a connected manometer. Leave it for 8
hours. After that there should be no pressure drop within the next 24 hours.
6.6 Moisture in the refrigerant
Excess moisture in the cooling system results in a freeze-up, which blocks refrigerant flow in the
capillary tube. This can be diagnosed and repaired by replacing the dryer as in any medium
temperature refrigeration system.
1. Bleed off all refrigerant from the cooling system.
2. Evacuate stage < 1 hPa.
3. Replace vacuum with R 134a bringing pressure up to slightly above zero gauge.
4. Replace dryer.
5. Increase pressure with R 134a and leak test dryer connections.
6. Bleed off pressure.
7. Evacuate again as in point 2.
8. Replace refrigerant as described in the next paragraph.
6.7 Charging the system
In addition to the normal hand tools generally
required, it is necessary to have the following available :




A testing manifold
A flask with refrigerant (R 134a)
A glass filler.
A vacuum pump (efficiency <1 hPa).
optional
Vacuum pump
R 134a
Make the set-up as shown in figure 2.
The cooling system and the cabinet or box must
be at ambient temperature, about 25°C before
the R 134a is filled.
Suction side
Pressure side
Compressor
Note!
Fig.2
- Switch off the cooling bath 2 hours before filling R 134a, in order to
reach ambient temperature.
- Keep the bath switched off during evacuation
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Cooling Bath
6.8 Charging Procedure
1.
Start the vacuum pump, open the valve on the service manifold (see manual for the service
manifold used) to make a connection between the suction side of the compressor and the
vacuum pump.
2. Close off the connection between the vacuum pump and the suction side.
3. Make a connection to R 134a flask and suction side. Fill R 134a into the system until 1.1 bar
absolute pressure is reached.
4. Close connection to R 134a flask.
5. Repeat evacuation as explained in point 1.
6. Repeat point 2, 3, and 4.
7. Repeat point 1 (Evacuation).
8. Fill glass filler to 400 g with R 134a. Please check with the label on the bath.
9. Make a connection between glass filler and suction side. Fill R 134a into the system.
10. When the filling of R 134a is completed, close the process stub of the compressor and solder it
with a silver soldering.
7. Technical Data
General
Description
DxWxH [mm]
Weight [kg]
Required power supply [V / Hz]
Max. Power consumption [W]
Insulation rate [mm]
Cooling bath
CBN 8-30
439x273x521
31
230 / 50
325
50
Cooling bath
CBN 18-30
469x423x672
47
230 / 50
800
50
Cooling bath
CBN 28-30
644x423x672
55
230 / 50
800
50
Resistance Table at +20 °C
Model
Resistance Main
Resistance Start
CBN 8-30
7.4 
28 
CBN 18/28-30
5.7 
17.5 
Operating parameters
Description
Temperature Range [°C]
Working Temp. Range [°C]
Liquid Volume [L]
Cooling Capacity at +20 °C
-30 ..200
-30 ..200
-30 .. 120 (100*)
-30 .. 120 (100*)
8
18
600
900
* for continuous operation
Environmental
Description
Temperature Range [°C]
Relative Humidity [%]
Protection Class
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5 .. 32
15 .. 80
IP 21D
-30 .. 200
-30 .. 120 (100*)
28
900
Cooling Bath
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8. Electrical Diagrams
8.1 Wiring Diagram
8.2 Compressor diagram
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9. Cooling Diagram
10. Spare parts
The position numbers in the table below refers to the position indication in the diagram above.
Pos:
1
2
3
4
5
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Description
Compressor
CBN 8-30
Electrolux GL 90 TB
CBN 18 / 28 -30 Electrolux GP 12 FB
Condenser
Fan motor
Filter dryer
Heat exchanger
Stock number
95800001
95800006
88847502
88864007
not replaceable