repair mini split - POE oil

[PoorOwner]

Need to repair one of the flares that is leaking. (not installed by me). System still running ok, just noticed oily film on that fitting.

How much oil is residing in the evaporator and lineset? I am sure they have a film of oil coating the lines and in the evap.

Anyway, I am concerned about the POE oil, it is hygroscopic and absorb moisture, only a desiccant can remove the moisture from the oil.
But, mini split systems don't have driers to replace nor do they want you to install one.


here is a publishing that I found

"Polyolester Oils
POE oils are VERY hygroscopic. They readily
absorb moisture and hold it. For this reason POE oils
should be limited in their exposure to ambient air during
manufacture or service. The lubricant should be exposed
to ambient air for no more than 15 minutes. "


1) So how long do you think I can work with the lineset opened up?

2) Would flowing a tiny bit of nitrogen so it is at positive pressure help?

3) is it true running in high cooling mode returns most of the oil into the compressor?

 

[Trey T]

1) hours. They're talking about the compressor open to atmosphere. Close the two king valves at the condenser to isolate it from atmosphere.
2) may be but you gotta be wasting a lot of nitrogen to fill the space ... probably couple hundred bucks of nitrogen ... for hrs. fix the issue and vacuum the system to boil off the moisture; then open up the king valves again
3) not true. the POE is soluble to the R410a refrigerant. If the refrigerant is moving, the oil is moving along and gets carried back to the pump.

There's a caveat to the instruction above. In order to account the loss refrigerant, you have to remove the existing amount and figure out the difference. Then put it all back in and add the appropriate amount.

 

[PoorOwner]

Thanks for your input.

I am aware of needing to weight in the exact charge and there is no guessing or top off method.

 

[alexb2000]

This will sound stupid, but have you tried tightening the fitting? I have a flare torque wrench for mini-splits and I notice it will under-torque if the threads are dry and/or slightly damaged. I always give the threads and flare face a little wipe of Nylog to prevent this.

If you do open it up try to get a hold of a micron gauge to be sure you have a good vacuum.

 

[PoorOwner]

This will sound stupid, but have you tried tightening the fitting?

I have not. But I have tempted. I have heard of people tighten it more until the leak stop.

but I suspect there maybe a burr in the flare or imprint of it.
I don't remember seeing the installer deburr, or maybe he did.
if there was a burr (looks like a hair of copper) tightening it may put a imprint the surface of the brass.

I have heard of flare cracking, and I don't want to try to tighten things while under pressure. so I have decided to move refrigerant out of the lineset to 0 psig first.

I plan on taking off the nut and look at the flare, put some nylog, which shouldn't take more than a minute.
If the flare appear to be smooth and then the problem was that it was not tightened enough and I have should chance to compress it more.

in the worse case is i still have a leak.
I think lineset looks a little short to make another flare. I have 2 lineset going to it so it's tough to move the machine a little closer.

 

[Git]

I am certainly not an expert - but if you have a small leak, since the system is under pressure, wouldn't it be safe to say that your POE oil in the system should be unaffected?

Secondly, I am pretty sure that on my Mr. Slim, I can 'pump down' everything back into the 'outdoor unit', just like it came from the factory. Can't you do that with your system? You would then just have to go through the normal startup up once the leak was repaired

 

[justinjoyal]

Pump down, fix the leak, leak test, proper vacuum, let it rip!

 

[rlitman]

...I have heard of flare cracking, and I don't want to try to tighten things while under pressure. so I have decided to move refrigerant out of the lineset to 0 psig first...

Good point.

I've been told that pre-flared linesets come with flare nuts that are inferior to the nuts that come with the mini-split components, and that you should always cut off the pre-made flares. Something about the R410a pressures being higher, requires a stronger flare nut.

 

[Jackfre]

Do not use nyloc on the fittings. Put a small wipe of the POE oil on the face and shoulder of the flare. Nothing else. I've seen many warranties refused due to the use of "pipe dope", etc on the condensing unit flares. Reclaim, Nitrogen, evacuate, recharge. It is the only thing that works.

 

[PoorOwner]

Do not use nyloc on the fittings. Put a small wipe of the POE oil on the face and shoulder of the flare. Nothing else. I've seen many warranties refused due to the use of "pipe dope", etc on the condensing unit flares. Reclaim, Nitrogen, evacuate, recharge. It is the only thing that works.

It is nothing like a pipe dope. It’s nylog you maybe thinking of nyloc which is more like a fasterner locker.

 

[justinjoyal]

Nylog is not needed on flares but it’s fully compatible with R410A. The way it remains gooey greatly reduces contamination risks anyway.

 

[Jackfre]

A good flare will not need anything other than a bit of oil on the face of the flare. Regardless of whether it is compatible with 410a, and thanks for that info,JR, I have seen people have trouble getting a sealed system and put "stuff" on the flares. It doesn't work, the unit gets pulled as defective. I as the rep get a call to inspect the pulled unit. One of the things I was directed to inspect was the flares. If there was anything on them, Fujitsu would refuse the warranty. It was not negotiable. Just be careful with your install and make sure you aren't creating problems for yourself if things go sideways. Good luck.

 

[alexb2000]

Here's a good thread about Nylog:

http://hvac-talk.com/vbb/showthread.php?1279551-REVIEW-Nylog-Gasket-and-Thread-Sealant

Don't knock it until you try it.

 

[Git]

One of the things I was directed to inspect was the flares. If there was anything on them, Fujitsu would refuse the warranty. It was not negotiable. Just be careful with your install and make sure you aren't creating problems for yourself if things go sideways. Good luck.

So if a unit had a blown circuit board or similar electronic failure and your find 'something' on the line set flares, you're going to refuse the warranty?


Note to self - never buy anything from Fujitsu

 

[PoorOwner]

it's fujitsu..
no warranty if bought online. But their inventory makes it to the online retailers.
no warranty if you didn't install a disconnect switch. etc.
no warranty if you put nylog on the flares

no manuals online.


overall, the the 3 big Japanese AC companies need to work harder to stay on top, companies like Gree are slowly putting out products that out performs their products.