VRV II oil problems

[multisync]

We have inherited a site which has several VRV's installed in 2006 R410a.

Got a call about one blowing the trip. Checked it over found the 1st stage std gone bang.(It also looks like the inverter has been changed at some point too?)

We took the old one out and checked the oil. The first pic shows the amount of oil we got out of the comp with it upside dwon for 5 minutes. On speaking to DUK it possibly appears there has been carbonisation of the oil due to lack of nitrogen during installation. This has led to the oil return blocking and hence emptying out of the compressor.

Of course if this oil is bad then the rest of the oil in the system is bad.

The problem (or one of them) is that you cannot drain out the other two compressors as there is no drain point or equalisation line.

So we think we will have to remove the 3 x separators in a lump by unbrazing HG in/out + 1/4"oil return line. Then it can be lifted out and drain each pot out.Then we can return it and fill it with fresh oil.
We would like to uprate the silly little spun filter on each return line so we can filter what we can't remove to clean it up. Now I guess DUK won't warrenty any additional non std filter in the system but it's obvious the copper spun ones are no good for this job.

Throwing it out to the floor -what how why would you clean up a system like this

Multisync
London

[Thermatech]

When the oil is black like that the old oil acid test does not work.
So the system could have some acid contamination too.

I guess all you can do is put the price for the options in to the customer & let him decide.

The system could be repaired & cleaned up but its going to costs lots in labour.
The easy option is to install a new outdoor unit.
But then contaminated oil in the system could re contaminate the new oil in the new outdoor unit.

Suggest
1/ drain the oil out of the compressors & oil seperators / accumulator then replace with new oil.
2/ replace the blocked strainers.
3/ Install a replaceable core filter drier in the common suction such that all oil return from the oil seperators back to suction has to pass through the filter drier.
4/ Start with burn out filter drier core & then standard core.

That will clean up the system.

Had the same problem on a Hitachi VRF system this year.
End user opted for new outdoor unit + clean up procedure with core filter drier.

[multisync]

Hmm, much as I thought. The boss is very concerned that this is going to get very political (when he saw the pictures he groaned)

The problem I guess is that the install was done by their preferred installer (a D1) and the maintenance manager took a flier to get us in instead of the installer. So once they all know what's happened the SWHTF

Of course we are in the clear so to speak but it means we will get dragged into the argument about liability etc..

Many thanks for the advice I will let you now how it goes.

Multisync
London

[Reflexive]

In the older times, for cleaning something like this internally, R11 would be ideal. These days you'd get a good yelling for suggesting it. However I still will. If you've got it, at least use it, and properly use it.

On the other hand, some other high boiling point refrigerant with great solubility could help. R123 for instance.

Cut out the oil separators and drain for sure, flush them, reseal and recharge.

But if the oil's gone that bad your going to want to flush the entire system behind the oil separators.

[brunstar]

Well to have oil looking like that you are right with no OFN used on install, the best thing to do would be is to change the oil as much as you can and fit temperary driers on each compressor return as there will be more filth that will return, then change the filters again after about a month and check the state of them and the oil. the filters must not be left on though and need to be on the return at the compressor.

[agus sartono]

Can type compressor of Scrool use R 22 changed with gas of R 407 any kind of which need to be changed.

[El Padre]

Hi,
Had a similar problem last summer, but not quite as bad, replacing the outdoor unit was not an option so we did it with burn out driers and acid away neutralising agent, it has been for nearly eight months now with no problems.

Good Luck!

[multisync]

Yet to start as we are racked out at the moment.

However after 18 months running I believe most if not all of the muck will be in the outdoor unit so once we clean up I suspect it will be ok. (famous last words ;-)

Although we will also be fitting an 'oil charging stub' to the three separators so we can inspect the oil and drain down once a week and replace with new till it runs clean.

Strangely the two units next both have clean/clear oil so it's a strange one for sure..