Instructions
6 | AN293820378892en-000101
© Danfoss | DCS (CC) | 2019.01
• When brazing, protect the valves and all other
unit components from torch heat damage
(painted surfaces, gaskets, connecting box).
• Note that it is not necessary to remove com-
pressor shut-off valves for connection to the
system, hence no need to replace associated
gaskets.
• Be sure to connect the required safety and control
devices onto compressor shut-off valves or fittings.
• In case of oil return through the Schrader fitting
on the compressor shell, make sure the internal
valve is removed.
5 - Leak detection
Never use oxygen or dry air in order to avoid the
risk of fire or explosion.
• Perform a leak detection test on the complete
system by means of: a dry nitrogen pressure test,
a mixture of nitrogen and the refrigerant to be
used in the system, a helium leak test and/or a
deep vacuum test.
• The test should be long enough in duration to
ensure the absence of any slow leaks in the sys-
tem.
• Use tools specifically designed for detecting leaks.
• The low side test pressure must not exceed 1.1
x Ps pressure indicated on the compressor name-
plate.
• For high side test pressure, do not exceed the pres-
sure indicated on the condensing unit nameplate.
• Whenever the condensing unit is equipped
with suction and liquid shut-off valves, these
valves are to remain in the closed position while
performing the leak test (condensing unit leak
test already performed in the factory).
• Should a leak be discovered, proceed with re-
pair steps and repeat the leak detection.
• When a deep vacuum leak detection test is se-
lected, observe the following:
1) The level to reach is 500 μm Hg.
2) Wait 30 min.
3) If pressure increases rapidly, the system is
not airtight. Locate and repair leaks. Restart the
vacuum procedure, followed by steps 1, 2, etc.
4) If pressure increases slowly, the system
contains moisture inside. Break the vacuum with
nitrogen gas and restart the vacuum procedure,
followed by steps 1, 2, etc.
5) Connect the compressor to the system by
opening the valves.
6) Repeat the vacuum procedure, followed by
steps 1, 2, etc.
7) Break the vacuum with nitrogen gas.
8) Repeat the vacuum procedure, steps 1, 2;
a vacuum of 500 μm Hg (0.67 mbar) should be
reached and maintained for 4 hours. This pres-
sure is to be measured in the refrigeration sys-
tem, and not at the vacuum pump gauge.
Do not use a megohmeter or apply power to the
compressor while it is under vacuum, as this may
cause motor winding damage (motor burn-out).
Do not use colored leak detection fluids. Do
not use chlorofluorocarbon in leak testing sys-
tems designed for HFC fluids.
6 - Vacuum dehydration procedure
Whenever possible (if shut-off valves are pre-
sent), the condensing unit must be isolated from
the circuit. It is essential to connect the vacuum
pump to both the LP & HP sides, in order to avoid
dead-ending system parts.
Recommended procedure:
1) Once leak detection has been completed,
2) Pull down the system under a vacuum of
500 μm Hg (0.67 mbar).
3) When the vacuum level of 500 μm Hg has
been reached, the system must be isolated from
the pump.
4) A vacuum of 500 μm Hg (0.67 mbar) has
to be reached and maintained for 4 hours. This
pressure is to be measured in the refrigeration
system, and not at the vacuum pump gauge.
If pressure increases, restart the leak-detection
procedure (refer to the «Leak detection» section
of this manual if necessary).
Vacuum pump:
A two-stage vacuum pump with gas ballast
valve (0,04-mbar standing vacuum) shall be
used; its capacity is to be consistent with system
volume.
Never use the compressor as a vacuum pump. It
is recommended to use large-diameter connec-
tion lines and to connect these lines to the shut-
off valves, rather than to the Schrader connec-
tion.
This recommendation allows avoiding excessive
pressure losses.
Moisture level:
At the time of commissioning, system moisture
content may be as high as 100 ppm. During ope-
ration, the liquid line filter dryer must reduce this
level to < 20 ppm.
Additional notes:
• To improve moisture removal, the temperature
of the system should not be lower than 10°C.
• A proper vacuum procedure is even more im-
portant with HFC and polyolester lubricant than
it has “traditionally” been with HCFC (R22) or CFC
and mineral oil.
• For further details, please refer to TI 3-026.
Do not use a megohmeter or apply power to
the compressor while it is under vacuum, as this
may cause motor winding damage (motor burn-
out).
7 - Electrical connections
• Make sure the main power supply to the sys-
tem has been switched off and isolated, in ac-
cordance with applicable regulations, before
performing
any electrical connection.
• Please refer to Figs 5 and 6 for typical wiring
connections and examine the specific wiring
diagram located in the electrical box cover.
For further details, refer to the condensing unit
guidelines.
• Note that Maneurop® compressors fitted on
condensing units are protected against overhea-
ting and overloading by an internal safety motor
protector. However, an external manual reset
overload is recommended for protecting the cir-
cuit against over-current.
• The “must trip” value of this overload relay must
be set in accordance with power line sizing and
design and shall never exceed the “A max.” value
stamped on the nameplate.
• On units equipped with an electrical box, all
electrical connections (condenser fan motor,
compressor motor, pressure control switch,
crankcase heater, etc.) have already been wired at
the factory. For single-phase compressors, start-
and-run capacitors are included in the connec-
ting box.
• The connecting box is equipped with screw type
terminal blocks, for both power and control lines as
well as earth terminals for grounding connections.
• All electrical components must be selected as
per local standards and condensing unit compo-
nent requirements.
8 - Filling the system
• Before charging the refrigerant, verify that the
oil level is between 1/4 and 3/4 on the com-
pressor oil sight glass and/or ensure that the oil
charge of the original compressor is sufficient as
regards system dimension and piping design:
- An additional quantity of oil might be neces-
sary for line lengths (back and forth) in excess of
20 m.
- In the event additional oil is required, use
only an approved lubricant (refer to the «Intro-
duction» section of this manual).
• Make sure the refrigerant used to fill the system
is compatible with compressor design. Refer to
the
«Introduction»
section of this manual for an
approved list of refrigerants.
• Compressor switched off: the liquid refrigerant
is charged into the condenser and/or liquid re-
ceiver in the liquid phase (compulsory for refri-
gerant blends).The charge must be asclose to
the nominal system charge as possible in order
to avoid both low pressure operations and ex-
cessive superheating at start-up. Throughout
this operation, both compressor service valves
must remain closed.
• Remember that vapor-charging is only appro-
priate for pure refrigerants, such as R22.
• To the extent possible, maintain the refrigerant
charge below 2.5 kg per cylinder. Above this li-
mit, install a system, such as a pump-down cycle
or suction line accumulator, to prevent against
liquid flood-back into the compressor.
• Be sure that the refrigerant charge is suitable
for both winter and summer operations.
9 - Verification before commissioning
Ensure that all service valves are in the open
position before start-up. A closed discharge or
suction service valve may cause serious damage
to the compressor and/or compromise safety
device operation, thereby resulting in potential
injury to personnel.
