Danfoss VRJ Instruction Manual

Danfoss Inverter scroll
compressor, VRJ
For Residential Applications - R410A
Application Guidelines
http://danfoss.us.com/

Application Guidelines
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Introduction................................................... 4
Scroll compressor components....................................4
Compressor size..................................................................4
Performance.........................................................................4
Compressor model designation ................... 5
Nomenclature......................................................................5
Label........................................................................................5
Serial number ......................................................................5
Technical specications ................................ 6
Compressor specications..............................................6
Performance data ..............................................................6
Variable speed drive specications .............................6
Bearings lubrication ..........................................................6
Dimensions .................................................... 7
VRJ 028 - 035 - 044.............................................................7
Mounting grommet ..........................................................7
Electrical data, connections and wiring....... 8
Supply Voltage ...................................................................8
Compressor electrical specications...........................8
LRA (Locked Rotor Amp)..................................................8
MCC (Maximum Continuous Current) ........................8
Winding resistance ............................................................8
Wiring connections ..........................................................9
Terminal cover mounting................................................9
Terminal cover removal....................................................9
IP rating..................................................................................9
Internal motor protection...............................................9
Phase sequence and reverse rotation protection ..9
Approvals and certicates ........................... 10
Approval and certicates ...............................................10
Pressure equipment directive 97/23/EC ..................10
Low voltage directive 73/23/EC, 93/68/EC...............10
Internal free volume.........................................................10
Operating conditions ................................... 11
Refrigerant and lubricants .............................................11
Motor supply.......................................................................11
Compressor ambient temperature.............................11
Application envelope ......................................................12
High and low pressure protection ..............................13
Crankcase heating ............................................................13
Oil return management..................................................13
On/o cycling (cycle rate limit)....................................14
Start-up sequence.............................................................14
System design recommendations .............. 15
General..................................................................................15
Essential piping design considerations.....................15
Refrigerant charge limit .................................................16
Reversible heat pump systems ....................................16
Minimum sump superheat............................................16
Preventing liquid ood back ........................................16
Water utilising systems ..................................................17
Loss of charge protection...............................................17
Oil level checking and top-up ......................................17
Sound and vibration management............. 18
Starting sound level .........................................................18
Running sound level ........................................................18
Stopping sound level.......................................................18
Sound generation in a refrigeration system and air
conditioning system ........................................................18
Installation .................................................... 20
System cleanliness............................................................20
Compressor handling and storage .............................20
Compressor mounting....................................................20
Compressor holding charge..........................................20
Tube brazing procedure .................................................20
Brazing material.................................................................20
Compressor connection .................................................21
Vacuum evacuation and moisture removal.............21
Liquid line lter driers......................................................22
Refrigerant charging........................................................22
Insulation resistance and dielectric strength..........22
Compressor replacement after motor burn out ....22
Ordering information and packaging ........ 23
Packaging ............................................................................23
Ordering code numbers .................................................23
Content

Application Guidelines
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Introduction
Scroll compressor
components
Compressor size
Performance
Danfoss VRJ for residential applications
developed by Danfoss is a complete package
consisting of a dedicated variable speed
compressor, variable speed drive, application
controller, electronic expansion valve (EEV), EEV
controller and sensors. Three nominal system
sizes are available (3, 4 and 5 TR), based on three
compressor models.
These Selection & Application Guidelines focus
on the variable speed scroll compressor.
The motor stator is rigidly attached to the shell.
The rotor is shrink-t onto the eccentric shaft. The
shaft is supported by two bearings, one in the
crankcase and the second below the motor.
Variable speed technology oers more exibility
in compressor selection than xed speed
compressors. Selection of the right variable
speed compressor size can be done by dierent
methods:
• Maximum cooling capacity: select a
compressor size that achieves the peak
load system cooling capacity demand at its
maximum speed.
• Nominal cooling capacity: select a
compressor size that achieves the nominal
system cooling capacity at a rotational
speed of 3000-4200 rpm (50-70Hz).
• Best Seasonal Eciency Ratio: select a
compressor size that achieves the minimum
system cooling demand at its minimum
speed. Ensure that the compressor is able to
cover the peak load system cooling capacity.
This selection makes the compressor to run
for a maximum of time at part load where
the system eciency is highest.
Danfoss scroll compressors are manufactured
using the most advanced machining, assembly,
and process control techniques. In design of
both the compressor and the factory, very high
standards of reliability and process control
were rst priority. The result is a highly ecient
product with the highest reliability obtainable,
and a low sound level.
The Danfoss VRJ compressors referenced in this
guide is a fully compliant scroll and actually
improves with run time in its early commissioning.
A seventy-two hour run-in is recommended to
meet performance expectations.

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Compressor model designation
Label
Serial number
MADE IN CHINA
Model no : VRJ044UKNP6
Serial no : NM2506117599 245 Max Inverter Driven
Drive Model: 176L0765
LR: 12.0 A MAX OPER: 30.0A
Lubricant:PVE / 57 oz/1.68L
2022
INVERTER PROTECTED
876543210
PROTECTED BY DOMESTIC AND FOREIGN PATENTS
Tech no : VGK46PHA01
Year code 8 Digit serial number
12345678A 25B
Plant assembly line code
Month code
Application, Family
& refrigerant
V: Variable speed
R: Residential
J: R410A, PVE lubricant
Swept Volume
Displacement in cc/rev
Model Variation
U: Design optimised for high SEER
Other features
6: No other features
Equipment version
P: Brased connections,
spade terminals
Motor protection
N: No internal motor
protection (protection by
drive)
Voltage
K: 420V DCL IPM
U
Model
Variation
028
Swept
Volume
VRJ
Application,
Family
& Refrigerant
K
Voltage
N
Motor
Protection
P
Equipment
Version
6
Other
Features
Nomenclature

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Technical specifications
Performance data
Variable speed drive
specications
Bearings lubrication
Compressor
model
Swept
volume Displacement Oil charge Net weight
cu.in/rev Min speed 30 Hz 60 Hz Max speed oz lb
900 rpm 1800 rpm 3600 rpm 4200 rpm
VRJ028 1.64 51 103 206 240 36 53
VRJ035 2.12 66 133 265 310 57 55
VRJ044 2.65 83 166 332 387 57 55
Compressor specications
For dedicated variable speed drive specications,
refer to “Danfoss VRJ Installation and Operation
instructions”.
A specic oil pump ensures optimal bearing
lubrication at all compressor speeds. This to have
sucient bearing lubrication at low speeds as well
as avoid excessive Oil Circulation Ratio (OCR) at
high speeds.
Conditions Compressor
model
Nominal
Tons
Compressor speed Compressor capacity Compressor
isentropic eciency
rpm Hz Btu/hr Ton
High SEER
conditions
(H)
VRJ028 3 Tons 3600 60 36700 3.06 66.2
4200 70 42700 3.56 64.9
VRJ035 4 Tons 3600 60 46400 3.87 67.6
4200 70 53400 4.45 65.1
VRJ044 5 Tons 3600 60 57800 4.82 68.3
4200 70 68100 5.68 67.0
CHEER
conditions
VRJ028 3 Tons 3600 60 36500 3.04 65.9
4200 70 42300 3.53 64.3
VRJ035 4 Tons 3600 60 46200 3.85 67.3
4200 70 53000 4.42 64.6
VRJ044 5 Tons 3600 60 57900 4.83 68.8
4200 70 68300 5.69 67.5
Heat Pump
conditions
VRJ028 3 Tons 3600 60 25100 2.09 59.7
4200 70 29300 2.44 58.8
VRJ035 4 Tons 3600 60 31800 2.65 61.0
4200 70 36700 3.06 59.0
VRJ044 5 Tons 3600 60 40200 3.35 62.2
4200 70 47300 3.94 61.2
SEER
conditions (I)
VRJ028 3 Tons 1800 30 21000 1.75 68.5
VRJ035 4 Tons 1800 30 26800 2.23 69.7
VRJ044 5 Tons 1800 30 34500 2.88 70.9
Conditions
Evaporating
Temperature
(°F)
Condensing
Temperature
(°F)
Superheat
(°F)
Subcooling
(°F)
High SEER
conditions (H) 50 115 20 15
CHEER
conditions 45 100 20 15
Heat Pump
conditions 30 110 20 15
SEER
conditions (I) 55 100 20 15

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Dimensions
VRJ 028 - 035 - 044
Mounting grommet
0.067
1.614
Ø 1.614
1.161
5/16” - 18 UNC
self tapping
Recommended torque for mounting bolts:
8 ft.lbs (±1ft.lbs)
Ø 0.433
9.40
4 x Ø 0.75 - 0.78
3.750
5.06
4.38
2.74 - 2.80 34° 31°
45°
14°
4.32
3.750
7.491 - 7.509
9.40
7.491 - 7.509
15.53
Suction port
3/4” ODF
6.438 - 6.515
2.84 - 2.95
14.19
7.76 9.09
0.42
0.75
Discharge port
1/2” ODF
All dimensions in inch

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Electrical data, connections and wiring
Supply Voltage VRJ compressors must not be connected directly
to the mains supply. They must only be powered
through the dedicated Danfoss variable speed
drive.
Compressor model Variable Speed Drive Model
VRJ028 176L0767
VRJ035 176L0766
VRJ044 176L0765
Nominal voltage 208-230V – 1Ph – 60Hz
Voltage range 187 – 253 V
Refer to“Danfoss VRJ Installation and Operation
instructions” for more details about supply
voltage.
Compressor electrical
specications Compressor model LRA MCC Winding resistance
A A Ohm
VRJ028 10.2 18 0.296
VRJ035 12 23.5 0.254
VRJ044 12 30 0.254
LRA (Locked Rotor Amp)
MCC (Maximum Continuous
Current)
Winding resistance
LRA is the higher average current as measured
on a mechanically blocked compressor tested
under nominal voltage. LRA is printed on the
nameplate, according to UL requirements. With
VRJ compressors, the LRA value is low because the
variable speed drive reacts very rapidly (far below
1 second).
The MCC value is the maximum at which
the compressor can be operated in transient
conditions and out of the operating envelope. The
MCC value is measured based on UL conditions
(max load) and at low voltage.
VRJ scroll compressors are equipped with an IPM
(permanent magnet) motor.
Winding resistance is the resistance between
indicated terminal pins at 77°F (resistance value ±
7%).
Winding resistance is generally low and it requires
adapted tools for precise measurement. Use
a digital ohm-meter, a ‘4 wires’ method and
measure under stabilised ambient temperature.
Winding resistance varies strongly with winding
temperature ; If the compressor is stabilised at a
dierent value than 77°F, the measured resistance
must be corrected with following formula:
Rtamb= R77°F
a + t amb
a + t77°F
t77°F: reference temperature = 77°F
t amb : temperature during measurement (°F)
R77°F : winding resistance at 77°F
Rtamb : winding resistance at tamb
a: Coecient a= 390

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Electrical data, connections and wiring
Terminal cover mounting The terminal cover and gasket should be installed
prior to operation of the compressor. The terminal
cover has two outside tabs, 180 degrees apart, that
engage the terminal fence. When installing the
cover, check that it is not pinching the lead wires.
Terminal cover removal
Internal motor protection
Phase sequence and reverse
rotation protection
IP rating
Wiring connections
VRJ scroll compressors are not equipped with
an internal motor protector. Motor protection
is provided by the variable speed drive. All
motor para-meters are factory preset in order to
guaranty optimal locked rotor or overload current
protection.
The compressor will only operate properly in a
single direction. If electrical connections are done
correctly between the drive and the compressor
terminals (compressor and drive terminals T1, T2
and T3 matching), the drive will provide correct
phase supply to the compressor, and reverse
rotation will be not possible.
If compressor and drive T1, T2 and T3 terminals are
not matching, the compressor can go in reverse
rotation. This results in excessive noise, no pressure
dierential between suction and discharge, and
suction line warming rather than immediate
cooling. The compressor can be rapidly severely
damaged in these conditions.
The compressor terminal box IP rating according to CEI 529 is IP22 for all models. This IP rating is only
valid when correctly sized cable glands with the same IP rating are applied.
• First numeral, level of protection against contact and foreign objects
2 protection against object size over 1/2 inch (ngers of similar)
• Second numeral, level of protection against water
2protection against dripping water when tilted up to 15°
VRJ scroll compressors will only compress gas
while rotating counter-clockwise (when viewed
from the compressor top).
The drawing shows electrical terminal labelling
and should be used as a reference when wiring the
compressor.
T1, T2 and T3 of the drive and the compressor
must be connected accordingly.
Refer to“Danfoss VRJ Installation and Operation
instructions”for details and cable sizes.
Quick connect spade terminals
P terminal box type
push
push
push

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Approvals and certificates
Approval and certicates VRJ scroll compressors comply with the following
approvals and certicates.
Pressure equipment
directive 97/23/EC
Low voltage directive
73/23/EC, 93/68/EC
Internal free volume
Manufacturer's declaration of incorporation
ref. EC Machines Directives 98/392/CE Contact Danfoss
Products Internal free volume at LP side without oil (in.3)
VRJ028 - 035 - 044 200
Refrigerating uids Group 2
Category PED I
Evaluation module no scope
UL
(Underwriters Laboratories) All models
Other approvals / certicates Contact Danfoss

Application Guidelines
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Operating conditions
Refrigerant and lubricants
Motor supply
Compressor ambient
temperature
General information
High ambient temperature
PVE
Low ambient temperature
Residual moisture
When choosing a refrigerant, dierent aspects
must be taken into consideration:
• Legislation (now and in the future)
• Safety
• Application envelope in relation to expected
running conditions
• Compressor capacity and eciency
• Compressor manufacturer
recommendations & guidelines
Additional points could inuence the nal choice:
• Environmental considerations
• Standardisation of refrigerants and
lubricants
• Refrigerant cost
• Refrigerant availability
In case of enclosed tting and high ambient
temperature, it is recommend to check the
temperature of power wires and conformity to
their insulation specication.
Polyvinyl ether (PVE) is an innovative refrigeration
lubricant for HFC refrigerant systems. PVE is as
hygroscopic as existing polyolester lubricants
(POE), but PVE does not chemically react with
water; no acids are formed and compressor
evacuation is easier.
The compressor technology applied in Danfoss
VRJ scroll compressors in combination with PVE
lubricant provides the best possible result in
terms of reliability and compressor lifetime.
Although the compressor itself can withstand
low ambient temperature, the system may
require specic design features to ensure safe
and reliable operation. See below sections for
recommendations.
Prior to shipment from the factory, every
compressor is dehydrated, evacuated, and
charged with dry nitrogen. Maximum residual
moisture levels are 0.0082 oz. for model VRJ028,
and 0.0120 oz. for VRJ035 and VRJ044.
VRJ scroll compressors can be operated only
connected to the dedicated variable speed
drive, at nominal voltages as indicated in “supply
voltage” section. Under-voltage and over-voltage
operation is allowed within the indicated voltage
range.
VRJ scroll compressors can be applied from
-13°F to 125°F ambient temperature. The
compressors are designed as 100 % suction gas
cooled without need for additional fan cooling.
Ambient temperature has very little eect on the
compressor performance
VRJ scroll compressor application range is
inuenced by several parameters which need to
be monitored for a safe and reliable operation.
These parameters and the main
recommendations for good practice and safety
devices are explained hereunder:
Refrigerant and lubricants
Motor supply
Compressor ambient temperature
Application envelope (evaporating
temperature, condensing temperature, return gas
temperature)

Application Guidelines
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Operating conditions
The operating envelope for VRJ scroll
compressors is given in the gure below, where
the condensing and evaporating temperatures
represent the range for steady-state operation.
Under transient conditions, such as start-up
and defrost for heat pump applications, the
compressor may operate outside this envelope
for short periods.
The operating limits serve to dene the
envelope within which reliable operations of the
compressor are guaranteed:
• Maximum discharge gas temperature: +275°F
• Suction superheat is dedictated by the
minimum sump superheat (see graph p16).
• Maximum superheat of 40°F
• Minimum and maximum evaporating
and condensing temperatures, as per the
operating envelopes.
All the below limits, temperatures and speeds,
are secured by the parameters in the drive and
application controller software’s.
The discharge temperature depends mainly on
the combination of evaporating temperature,
condensing temperature and suction gas
superheat and speed. Discharge gas temperature
should be controlled with an insulated sensor
attached to the discharge line, 6 in. from the
compressor shell. Maximum discharge gas
temperature must not exceed 275°F when the
compressor is running within the approved
operating envelope.
Refer to“Danfoss VRJ Installation and Operation
instructions” for connection details, and to
“Sensor Selection Guideline” manual for
selection details and technical brochures about
temperature sensors.
Application envelope
Maximum discharge gas
temperature
35
45
55
65
75
85
95
105
115
125
135
145
155
900 - 4500 RPM
2100 - 3750 RPM
2200 - 3300 RPM
2300 - 2850 RPM
2400 RPM Derated
1100 - 4500 RPM
1300 - 4500 RPM
1500 - 4200 RPM
1800 - 4200 RPM
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
Saturated evaporating temp. (°F)
Saturated condensing temp. (°F)
2
6
10
14
18
22
26
30
34
38
42
46
50
54
58
62
66
70
-40 -36 -32 -28 -24 -20 -16 -12 -8 -4 0 4 8 12 16 20 24
(°C)
(°C)

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Operating conditions
Pressure settings
High pressure
Low pressure
High pressure ratio
Crankcase heating
Oil return management
R410A
Working pressure range high side psig 119 - 645
Working pressure range low side psig 28 - 202
Maximum high pressure safety switch setting psig 653
Minimum low pressure safety switch setting psig 22
: LP safety switch shall never be bypassed
According to UL requirements, a high pressure
safety switch is still mandatory in any system,
even with high pressure transmitters connected
and used via the variable speed drive.
HP switch settings shall not exceed the maximum
service pressure of any system components. The
high-pressure switch can be set to lower values
depending on the application and ambient
conditions. The HP switch must either be placed
in a lockout circuit or consist of a manual reset
device to prevent cycling around the high-
pressure limit. If a discharge valve is used, the HP
switch must be connected to the service valve
gauge port, which must not be isolated.
A low pressure (LP) safety switch is
recommended. Deep vacuum operations of a
scroll compressor can cause internal electrical
arcing and scroll instability. Danfoss scroll
compressors exhibit high volumetric eciency
and may draw very low vacuum levels, which
could induce such a problem. The minimum
low-pressure safety switch (loss of charge safety
switch) setting is given in the above table. Either
the LP safety switch must be a manual lockout
device or an automatic switch wired into an
electrical lockout circuit. The LP switch tolerance
must not allow for vacuum operations of the
compressor.
Scroll compressors are machines with xed
volume ratio, and operate more eciently
near the design pressure ratio. In the extreme,
do not exceed a 7.5:1 pressure ratio (absolute
discharge pressure to absolute suction pressure)
for extended periods. The Danfoss VRJ scroll
compressor is equipped with an internal pressure
relief valve for protection against blocked
condenser and fan failure conditions.
A crankcase heating function can be provided
by injecting a DC current in the motor of the
compressor, to keep the compressor warm, and
avoid liquid migration during o cycle.
Refer to“Danfoss VRJ Installation and Operation
instructions” for details.
A specic function can be enabled to secure
the oil return to the compressor. When the
compressor is running at minimum speed for
extended periods, every half hour, speed will be
increased to 2400 rpm for a 80 seconds period.
Suction and discharge pressure transmitters have
to be installed and connected to the variable
speed drive to ensure the compressor operates
within the application envelope described above.
Refer to“Danfoss VRJ Installation and Operation
instructions” for connection details, and to
“Sensor Selection Guideline” manual for selection
details and technical brochures about pressure
transmitters.
High and low pressure
protection

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14 AB141686422149en-US0401
Operating conditions
Start-up sequence To ensure correct lubrication of all the
mechanical parts, VRJ compressors start with
a dened ramp-up, and stay at a xed speed
for some seconds. Then the compressor speed
increases up to the desired set point according to
capacity request.
On/o cycling
(cycle rate limit)
The on/o cycling protection is included in the
variable speed drive. There is no need for extra
on/o cycling protection.

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System design recommendations
Proper piping practices should be employed to
ensure adequate oil return, even under minimum
load conditions with special consideration given
to the size and slope of the tubing coming
from the evaporator. Tubing returns from the
evaporator should be designed so as not to trap
oil and to prevent oil and refrigerant migration
back to the compressor during o-cycles.
It is particularly important and critical with
variable capacity systems, where very low
velocities can be achieved for long periods of
time, generating oil return issues.
If the evaporator lies above the compressor, as
is often the case in split or remote condenser
systems, the addition of a pump-down cycle
is strongly recommended. If a pump-down
cycle were to be omitted, the suction line must
have a loop at the evaporator outlet to prevent
refrigerant from draining into the compressor
during o-cycles.
If the evaporator were situated below the
compressor, the suction riser must be trapped so
as to prevent liquid refrigerant from collecting at
the thermal bulb location (see g. 1).
When the condenser is mounted at a higher
position than the compressor, a suitably sized
«U»-shaped trap close to the compressor is
necessary to prevent oil leaving the compressor
from draining back to the discharge side of the
compressor during o cycle. The upper loop also
helps avoid condensed liquid refrigerant from
draining back to the compressor when stopped
(see g. 2). The maximum elevation dierence
between the indoor and outdoor section
cannot exceed 26 feet. System manufacturers
should specify precautions for any applications
that exceed these limits to ensure compressor
reliability.
Piping should be designed with adequate three-
dimensional exibility. It should not be in contact
with the surrounding structure, unless a proper
tubing mount has been installed. This protection
proves necessary to avoid excess vibration, which
can ultimately result in connection or tube failure
due to fatigue or wear from abrasion. Aside from
tubing and connection damage, excess vibration
may be transmitted to the surrounding structure
and generate an unacceptable noise level within
that structure as well (for more information on
noise and vibration, see the section on: “Sound
and vibration management” section.
Essential piping design
considerations
Successful application of scroll compressors
is dependent on careful selection of the
compressor for the application. If the compressor
is not correct for the system, it will operate
beyond the limits given in this manual. Poor
performance, reduced reliability, or both may
result.
General
0.5 % slope,
13 ft/s or more
0.5 % slope,
13 ft/s or more
U-trap
U-trap, as short as possible
U-trap, as short as possible
max. 13 ft
fig.1
max. 13 ft
26 to 40 ft/s
To condenser
Evaporator
Condenser
HP
U-trap
3D flexibility
Upper loop
LP
fig. 2

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16 AB141686422149en-US0401
System design recommendations
Reversible heat pump
systems
Minimum sump superheat
Preventing liquid ood back
Transients are likely to occur in reversible heat
pump systems, i.e. a changeover cycle from
cooling to heating, defrost or low-load short
cycles. These transient modes of operation may
lead to liquid refrigerant carryover (or ood
back) or excessively wet refrigerant return
conditions. As such, reversible cycle applications
require specic precautions for ensuring a long
compressor life and satisfactory operating
characteristics. Specic tests for repetitive ood
back are required to conrm whether or not
special system design considerations should be
considered.
The minimum sump temperature is in the range
from 10°F to 30°F above saturated suction
temperature. Refer to the ood back test criteria.
Danfoss recommends the use of an electronic
expansion valve for all air conditioning and heat
pump applications with VRJ compressors. An
EXV has two key benets: it provides modulating
control of the system under varying load
conditions, and it protects the compressors from
ood back during adverse running conditions.
Exceptions to the use of EXV’s with Danfoss
VRJ must be approved by Danfoss application
engineering.
Scroll compressors can tolerate liquid refrigerant
up to a certain extend without major problems.
However, excessive liquid refrigerant in the
compressor is always unfavourable for service
life. Besides, the installation cooling capacity may
be reduced because of the evaporation taking
place in the compressor and/or the suction line
instead of the evaporator. System design must be
such that the amount of liquid refrigerant in the
compressor is limited. In this respect, follow the
guidelines given in the section: “Essential piping
design recommendations” in priority.
Refrigerant charge limit
0
5
10
15
20
25
30
35
40
-10 0 10 20 30 40 50 55
Acceptable
Unacceptable
Floodback requirement
Sump superheat, °F
Saturated suction temp. °F

Application Guidelines
17AB141686422149en-US0401
System design recommendations
Oil level checking and
top-up
Loss of charge protection
In installations with good oil return and line
runs up to 50 ft, no additional oil is required. If
installation lines exceed 50 ft, additional oil may
be needed. 1 or 2% of the total system refrigerant
charge (in weight) can be used to roughly dene
the required oil top-up quantity.
Always use oil from new cans.
Top-up the oil while the compressor is idle. Use
any accessible connector on the compressor
suction line and a suitable pump.
VRJ scroll compressors together with the variable
speed drive include a loss of charge protection
function. This protection is ensured if pressure
and temperature sensors are connected to the
drive.
Water utilising systems Apart from residual moisture in the system
after commissioning, water could also enter the
refrigeration circuit during operation. Water in
the system shall always be avoided. Not only
because it can shortly lead to electrical failure,
sludge in sump and corrosion but in particular
because it can cause serious safety risks.
Common causes for water leaks are corrosion and
freezing.
Corrosion: Materials in the system shall be
compliant with water and protected against
corrosion.
Freezing: When water freezes into ice its volume
expands which can damage heat exchanger
walls and cause leaks. During o periods water
inside heat exchangers could start freezing when
ambient temperature is lower than 32°F. During
on periods ice banking could occur when the
circuit is running continuously at too low load.
Both situations should be avoided by connecting
a pressure and thermostat switch in the safety
line.

Application Guidelines
18 AB141686422149en-US0401
Sound and vibration management
Running sound level
Stopping sound level
Sound generation in a
refrigeration system and air
conditioning system
Compressor sound radiation
During start-up transients, it is natural for the
compressor sound level to be slightly higher
than during normal running. Danfoss scroll
compressors exhibit very little increased start-up
transient sound.
VRJ scroll compressors are designed with
optimised discharge ports and wrap geometry
to reduce the sound level when a compressor is
running.
VRJ scroll compressors have very low shutdown
sound due to minimal volume of discharge
volume to push scrolls in reverse at shutdown.
Due to this small re-expansion, there is no
internal break mechanism required to prevent
reverse spin of the scroll set.
Typical sound and vibration in refrigeration and
air conditioning systems encountered by design
and service engineers may be broken down into
the following three source categories.
Sound radiation: This generally takes an
airborne path.
Mechanical vibrations: These generally extend
along the parts of the unit and structure.
Gas pulsation: This tends to travel through the
cooling medium, i.e. the refrigerant.
The following sections will focus on the causes
and methods of mitigation for each of the above
sources.
For sound radiating from the compressor, the
emission path is airborne and the sound waves
are travelling directly from the machine in all
directions.
The VRJ scroll compressor is designed to be quiet
and the frequency of the sound generated is
pushed into the higher ranges, which not only
are easier to reduce but also do not generate the
penetrating power of lower-frequency sound.
Use of sound-insulation materials on the inside of
unit panels is an eective means of substantially
reducing the sound being transmitted to the
outside. Ensure that no components capable
of transmitting sound/vibration within the unit
come into direct contact with any non-insulated
parts on the walls of the unit.
Because of the Danfoss unique design of a full-
suction gas & oil cooled motor, compressor body
insulation across its entire operating range is
possible.
Starting sound level
Sound level vs Speed
56
58
60
62
64
66
68
70
72
74
76
78
45/130
4200
45/130
3600
45/100
3600
45/100
2400
45/100
1800
45/100
900
Condition (Tsat(suction) / Tsat (discharge) and speed (RPM)
Sound power level (dBA)

Application Guidelines
19AB141686422149en-US0401
Sound and vibration management
Speed bypass
Gas pulsation
Mechanical vibrations
If vibrations still occur at some typical
frequencies, a speed bypass function is available
within the VRJ. This function allows avoiding
some frequency ranges and avoiding vibrations
to occur. Refer to “Danfoss VRJ Installation and
Operation instructions”for setting details.
The VRJ scroll compressor has been designed
and tested to ensure that gas pulsation has been
optimised for the most commonly encountered
air conditioning pressure ratio. On heat pump
installations and other installations where the
pressure ratio lies beyond the typical range,
testing should be conducted under all expected
conditions and operating congurations to
ensure that minimum gas pulsation is present. If
an unacceptable level is identied, a discharge
muer with the appropriate resonant volume
and mass should be installed. This information
can be obtained from the component
manufacturer.
Vibration isolation constitutes the primary
method for controlling structural vibration. VRJ
scroll compressors are designed to produce
minimal vibration during operations. The use
of rubber isolators on the compressor base
plate is very eective in reducing vibration
being transmitted from the compressor to
the unit. Rubber grommets are supplied with
all Danfoss compressors. Once the supplied
rubber grommets have been properly mounted,
vibrations transmitted from the compressor base
plate to the unit are held to a strict minimum.
In addition, it is extremely important that the
frame supporting the mounted compressor be
of sucient mass and stiness to help dampen
any residual vibration potentially transmitted to
the frame. The tubing should be designed so as
to both reduce the transmission of vibrations to
other structures and withstand vibration without
incurring any damage. Tubing should also be
designed for three-dimensional exibility.
During unit development, the complete
compressor speed range should be covered, in
order to dene if abnormal vibrations occur or
not. As ultimate solution, speed bypass can be
applied.
For more information on piping design, please
see the section entitled “Essential piping design
considerations”.

Application Guidelines
20 AB141686422149en-US0401
Installation
System cleanliness
Compressor handling and
storage
Compressor mounting
Compressor holding charge
Tube brazing procedure
Brazing material
Each VRJ scroll compressor is shipped with
printed Instructions for installation.
The refrigerant compression system, regardless
of the type of compressor used, will only provide
high eciency and good reliability, along with a
long operating life, if the system contains solely
the refrigerant and oil it was designed for. Any
other substances within the system will not
improve performance and, in most cases, will be
highly detrimental to system operations.
The presence of non-condensable substances
and system contaminants, such as metal
shavings, solder and ux, has a negative impact
on compressor service life. Many of these
contaminants are small enough to pass through a
mesh screen and can cause considerable damage
within a bearing assembly. The use of highly
hygroscopic PVE oils in R410A compressors
requires that the oil be exposed to the
atmosphere just as little as possible.
System contamination is one of main factors
aecting equipment reliability and compressor
service life. It is important therefore to take
system cleanliness into account when assembling
a refrigeration system.
During the manufacturing process, circuit
contamination may be caused by:
• Brazing and welding oxides,
• Filings and particles from the removal of
burrs in pipe-work,
• Brazing ux,
• Moisture and air.
Consequently, when building equipment and
assemblies, the following precautions must be
taken: never drill holes into the pipe-work after
installation.
Compressors are provided with a lifting lug. This
lug should always be used to lift the compressor.
Once the compressor is installed, the lifting
lug should never be used to lift the complete
installation. The compressor must be handled
with caution in the vertical position, with a
maximum inclination of 15° from vertical. Store
the compressor between -30°F and 120°F, not
exposed to rain or corrosive atmosphere.
Maximum inclination from the vertical plane,
while operating must not exceed 7 degrees.
All compressors are delivered with 4 rubber
grommets and metal sleeves. Compressors must
always be mounted with these grommets.
Each compressor is shipped with a nominal dry
nitrogen holding charge between 6 psi and 10
psi, and is sealed with elastomeric plugs. The
plugs should be removed with care to avoid oil
loss when the holding charge is released. Remove
the suction plug rst and the discharge plug
afterwards. The plugs shall be removed only
just before connecting the compressor to the
installation in order to avoid moisture entering
the compressor. When the plugs are removed, it
is essential to keep the compressor in an upright
position to avoid oil spillage.
Do not bend the compressor discharge or suction
lines or force system piping into the compressor
connections, because this will increase
stresses that are a potential cause of failure.
Recommended brazing procedures and material,
are described on following page.
For copper suction and discharge ttings, use
copper-phosphorus brazing material. Sil-Fos® and
other silver brazing materials are also acceptable.
If ux is required for the brazing operation, use
coated rod or ux core wire. To avoid system
contamination, do not brush ux on.