Test procedure

[ascorone]

Hey guys,

I hope somebody will help me for understanding compressor oil test procedure. We are planing to produce reversible heat pumps with combination of ventilation unit.

Compressor manufacturer advised to make oil tests. A few of them are a little bit unclear for me:
- I should perform oil test with minimum refrigerant flow (minimum refrigerant flow is when evaporating temperature is minimum and condensing temperature is maximum)

Question: should I perform this test in both modes (summer/winter)? Or minimum refrigerant flow is only in winter?

- I should perform oil test with maximum oil circulation degree (maximum oil circulation degree is when evaporating and condensing temperatures are maximum).

Question: should I perform this test in both modes (summer/winter)? Or maximum circulation flow is only in summer?

I hope somebody can provide me answers, thank you in advance.

[Brian_UK]

What sort of test of the oil is required?

[ascorone]

Brian, minimum oil level in compressor. Before massive production of units oil tests should be made. For these oil tests, compressor with mounted sight glass is required. Sight glass is mounted into bottom part of compressor and during each testing phase/mode/conditions you can directly see what level is in the compressor. For proper compressor functionality oil level in compressor should be above minimum value all the time.

[Brian_UK]

I think that you have answered your own question, you look at the oil sight glass to see what the level is.

Until the compressor is running then the oil does not move, it is up to you to ensure good oil return is achieved when the system is running.

[Rob White]

.

Looking at your first post and the last one, if I understand you
correctly, the test is referring to oil return back to the compressor
via the suction line.

Mass flow rates of the refrigerant will affect the oil return so that
is why the test is done at minimum flow rates (mass flow).

If the evaporator is below the compressor then traps in the suction
will be required. The size of the pipe is a factor as well.

So if it is a reversible heat pump the oil passing round the system
will have to be calculated and that will mean the oil return must be
in heating and cooling mode.

Rob

.

[ascorone]

.

Looking at your first post and the last one, if I understand you
correctly, the test is referring to oil return back to the compressor
via the suction line.

Mass flow rates of the refrigerant will affect the oil return so that
is why the test is done at minimum flow rates (mass flow).

If the evaporator is below the compressor then traps in the suction
will be required. The size of the pipe is a factor as well.

So if it is a reversible heat pump the oil passing round the system
will have to be calculated and that will mean the oil return must be
in heating and cooling mode.

Rob

.

Rob - yes, exactly.

Some question about traps. As I mentioned it's reversible air-to-air heatpump. In cooling mode, evaporator is in the same height as compressor, condenser above evaporator per evaporator height. Same application in heating mode, condenser is in the same height as compressor, evaporator is above condenser per evaporator height.

If compressor is moreover in the same height with compressor (cooling mode), then traps are unnesccesary? Also in winter, evaporator is above compressor, traps are also unnescessary?

[ascorone]

If compressor is moreover in the same height with compressor (cooling mode), then traps are unnesccesary? Also in winter, evaporator is above compressor, traps are also unnescessary?

Any suggestions about traps?

[ascorone]

Any suggestions about traps? Anyone?

[Rob White]

.

Traps tend not to be installed in AC / heat-pumps because
of the reverse cycle so if you are designing a system from scratch
you must get your mass flows , pipe diameter and pipe length correct.

Normal design has traps in riser's every 4 metres or so but AC very
rarely do. I have no answers for you because your system will be self
designed.

Regards

Rob

.

[ascorone]

.

Traps tend not to be installed in AC / heat-pumps because
of the reverse cycle so if you are designing a system from scratch
you must get your mass flows , pipe diameter and pipe length correct.

Normal design has traps in riser's every 4 metres or so but AC very
rarely do. I have no answers for you because your system will be self
designed.

Regards

Rob

.

Thanks Rob!