pipe lenght vis a vis oil traps

[kerrcell]

Hey Guys,

Yesterday vbeen on a hitachi HAS-12HNC.Found shorted compressor insulation !! Between the 5 indoors and the top roof level outdoor there are 7 storeys. There is not a single oil trap. Does not consider it normal . what are the views ? VRFs allowable to be a straight pipe or ? I cannot understand how the oil will be pulled up in that height back to compressor. Am I missing something ?

[CraigF]

I was always told, never trap a jap!! However, always follow the manufacturers instructions!!

[The Viking]

Always, always follow the manual. Or as we say over here RTFM.

Although I believe all VRV/VRF manufacturers are the same, I can only tell you for certain how the Samsung kit works.
No oil traps allowed regardless of rise or pipe length. The system will periodically enter what is known as "oil recovery". Basically the system open the indoor valves, raising the velocity of the refrigerant and pushing the oil back to the compressor.

:cool:

[install monkey]

no oil traps,double risers,service valves onn any vrf as long as the install is within the design limitations then no issues

[kerrcell]

Hi Guys,

Thanks for replies. Yes actually that cannot insert oil traps in fancoils !! I mean the riser in my email. The riser is 7 storeys high and found system already there. I am trying to figure out prior to change compressor.

Question is :

The pipe work from Outdoor unit on roof goes down through a 7 storey shaft with no oil traps.Should there be one ?

[The Viking]

Short answer is "most likely not".

Your best bet is to get hold of the installation manual for the system in question or call Hitachi.

:cool:

[AC_From_Hell]

I also confirm that most VRF systems do not need oil traps.

There are enough oil recovery mechanisms installed in the outdoor unit, which seem to be well working at least in my installations.

[AlexAlex]

I also confirm that most VRF systems do not need oil traps.

There are enough oil recovery mechanisms installed in the outdoor unit, which seem to be well working at least in my installations.

1. HITACHI RAS-12HNC very good airconditioner.

2. But it is not VRF! It is Utopia Splits (RAS-12HNC - IVX standart)
http://www.hitachiaircon.com/argws/en/ranges/utopia

3. There is a function "oil recovery" or not in Utopia IVX standart - is unknown. In the service manual (SMGB0079 rev.0 - 01/2013) information is not available. :confused:

4. IVX standart - maximum 4 indoor unit (IDU). IF 5 IDU - it is not good for oil return.


kerrcell
5. What is the total cooling capacity of indoor units?

6. "Between the 5 indoors and the top roof level outdoor there are 7 storeys"
7 storeys - how many meters of height difference ?

7. Tell what position switches DIP DSW2 on PCB outdoor unit ?

Best regards,
Alex

[AlexAlex]

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