1.
2.
1.
2.
3.
1.
2.
3.
1.
2.
Application
Manage oil in the circuit
Requirement
Oil level must be visible or full in the sight glass when the compressor is running and when all compressors of
the circuit are stopped. For DSF155-200 trio models, top-up oil quantity 1L at least as mandatory.
System evaluation
Table 23: System evaluation
Split type
Single compressor
Manifold compressors
Non split
Test No.1
Test No.1+2
Split
Test No.1+3
Test No.1+2+3
Test, criteria and solutions
Table 24: Test, criteria and solutions
Test No.
Purpose
Test conditions
Pass criteria
Solutions
1
Check proper oil
return
A
Lowest foreseeable evaporation, and highest foreseea-
ble condensation.
Minimum number of compressor
running for 6 hours.
For reversible system, perform test in both heating and
cooling mode.
Oil level must be visible or full in the
sight glass when the compressor is
running and when all compressors of
the circuit are stopped.
Top-up with oil, generally 3% of
the total system refrigerant
charge (in weight). Above 3%
look for potential oil trap in the
system.
Integrate a function in control
logic to run all compressors si-
multaneously in order to boost
oil return (for more details see
section
).
Oil separator can be added
2
Check oil balanc-
ing
A
Lowest foreseeable evaporation and highest foreseeable
condensation and nominal capacity condition
For tandem 2 compressors running for 6 hours, for trio,
compressor running follow the running sequence:
(1+2+3)2hrs
→
(1+2)2hrs
→
(2+3)2hrs
→
(1+3)2hrs
For reversible system, perform test in both heating and
cooling mode.
Oil level must be visible or full in the
sight glass when the compressors
are running and when all compres-
sors of the circuit are stopped
Top-up with oil, generally 3% of
the total system refrigerant
charge (in weight).
Check that manifold piping is
conform to Danfoss require-
ments.
Integrate a function in control
logic to stop manifold periodi-
cally in order to balance oil (for
more details see section
).
3
Oil return in split
systems
Since each installation is unique, test 1 and 2 can not
fully validate the oil return. Oil level must be checked
and adjusted at commissioning.
Oil level must be visible or full in the
sight glass when the compressor is
running and when all compressors of
the circuit are stopped.
Pay special attention to “Piping
design”
Oil separator is strongly recom-
mended, especially in case of
part load.
Manage sound and vibration
Sound radiations
We can consider two means to reduce compressors sound radiations:
Acoustic hoods are quick and easy to install and do not increase the overall size of the compressors. Acoustic
hoods are available from Danfoss as accessories. Refer to the tables above for sound levels, attenuation and code
numbers.
Use of sound-insulation materials on the inside of unit panels is also an effective mean to reduce sound
radiation.
NOTE:
During compressor shut down, a short reverse rotation sound is generated. The duration of this sound depends on
the pressure difference at shut down and should be less than 3 seconds. This phenomenon has no impact on
compressor reliability.
© Danfoss | Climate Solutions | 2023.06
AB309735209512en-000603 | 41
Scroll compressors, DSF090 to DSF530 | Application
