Acid cleanup

[Larry2]

Most recommendations I've read concerning acid cleanup say to replace the filter/drier early and often. Install the new compressor, then replace the filter after a brief period or running and check for acid again. Like shampoo, rinse-lather-repeat until clean is the advice.

One product says it will quickly move acid to the filter drier during the first hours of operation. The basic ingredient of this product is isopropyl alcohol, the same product MG Pony recommends for flushing the system. I find patent documents backing this idea, but I don't find many reports for this procedure.

I've read some discussions about flushes. Some of these describe great problems with removing flush products because they settled in low spot of the system where they weren't readily evacuated. I calculate 8 literes of volume in the pipework. Even a tiny bit left behind is an enormous contamination.

What is common practice on the residential side so filter driers can be exchanged without opening the system? Can a bidirectional filter/drier be installed between two refrigeration ball valves so only the short length between the valves and the filter/drier can be refrigerant-recovered and the drier changed? Are these valves a significant pertebation to refrigerant flow? Do they shut off well enough to do what I propose? Do these valves pose a source of future leaks? What do folks who stand behind compressor replacements practice in the field?

[taz24]

What do folks who stand behind compressor replacements practice in the field?

It does depend on what systems you work on.
Air cond requires a new comp a possibly a full system flush.
Commercial and industrial are a different ball game.
Replacing the comp and fitting new driers is sufficient for some large commercial systems. Industrial with open drive comps does not seem to suffer to much from acid in the system.

Horses for course's I supose

taz.

[Grizzly]

It does depend on what systems you work on.
Air cond requires a new comp a possibly a full system flush.
Commercial and industrial are a different ball game.
Replacing the comp and fitting new driers is sufficient for some large commercial systems. Industrial with open drive comps does not seem to suffer to much from acid in the system.

Horses for course's I suppose

taz.

A heavy night last night taz?
A open drive compressor doesn't have the motor winding in contact with the refrigerant.

Therefore a motor burn out is not going to contaminate the system.

However it can create some heavy duty smoke.

Although I am sure you knew all this!
Grizzly

[Larry2]

Yes, I neglected to mention my question concerns a hermetic compressor system. In this instance, it is a 3 ton heat pump and 80 foot of 3/8 & 3/4" lines.

[BigJon3475]

When possible replace refrigerant lines......if not possible rx-11 and nitrogen to push the sludge out. Replace with suction line filter and liquid line filter. Install the suction line filter where it will not be affected by the reversing valve if you can find a bi flow suction line filter dryer. If you can find filters that remove high acid that is good also. Monitor pressure/temp drop across the filters and replace as needed. If your just replacing a compressor it is recommended you replace everything that could hold the acid in it like reversing valves and accumulators as good practice.


Alcohol is about as hygroscopic as it gets....
http://www.refrig.com/acidin.html
http://www.nucalgon.com/nucalgon/nuc...1?OpenDocument
http://www.refrig.com/talk.html


Your best bet with a line set that long that runs through the building is to replace it.....if you have no other choices than rx-11 is out there but only run it through the line sets......make sure after the system is "cleaned" you pull a proper vacuum on the system.

[The MG Pony]

thats why alcohol makes such a good flushing agent and not to be used for any thing other then such, it cleans coils in a most impeccable manner, and then with a good strong blow through with N2 leaves them clean and dry.

And yes the Rx-11 contains Alcohol, albeit Ethyle.

[Larry2]

When possible replace refrigerant lines......

I think that is the conclusion I have reached too. I don't think I'll ever get all the contamination out of the condenser, evaporator and pipes to my satisfaction. The condenser concerns me the most since I hear trapped oil gurgle when I pass inert gas through. The circuits would need to be disassembled and flushed using a circulating pump. I think alcohol would be a good choice as MG Pony recommends. Pure ethanol would be my first choice because I have use for the left overs. This gear is just to old to keep tinkering.

I could probably squeak by a few more years. When I look at the ownership cost of old SEER 12.8 vs new SEER 15, it seems like now is the time to upgrade my system rather than have a crisis again during winter season.

I appreciate all the comments and I learned a lot from you guys, as always here.

[The MG Pony]

On ebay you can buy shells for filters and cores, ball valves will work long as they are rated for it, get your self some over sized cores and toss them in.

[Larry2]

After weeks of debate, I made the tough decision to junk the systems. I had one contractor say he would replace both ends but use the pipework over again. Opened up, the copper pipes smell like fire, no matter where you cut them open. I rinsed a one meter length with isopropyl. The oil didn't want to disolve. I don't think you would ever clear 30 meters of pipe with isopropyl when it's badly burned and etched.

I'm recycling the condenser coil from that system for a solar energy collector hobby tinkering project. It was surprising how easy it was to bend the coil out flat. I think I can get 10,000 btu daily, so break even should be fairly short. No one ever told me the pipes in these condesners is slightly larger than 3/8" elbows, so it will be a new project to build a manifold collector.



Here's a hint where that project is going, with this donated insulated glass assembly.



I needed to pull some fins free from the copper tubing as part of that project. There is aluminum oxide corrosion on the copper tubes. The aluminum fins no longer had an intimate thermal path to the copper condenser tubes.

I'm at the half way point for replacing this system. I replaced only the outdoor section on the small system. Mismatched with a wrong indoor coil, the numbers seemed okay after adjusting the charge. After some fits and starts, it is running nicely. Needless to say, one should never turn a system on it's side to measure for the elevation feet. The oil migrates where it doesn't belong.

As shipped, that unit must have been leaking at the service valve. I had to add nearly a full charge to make it run. As I opened the service valve, I heard very little gas charge the evacuted pipes and coil.

I started commissioning the system by first charging 20 oz compensation for the line set (after evacuation, or course) . Then I opened the valves and started it up. There was hardly any pressure. When I slowly added nearly full nameplate charge, it performed. My allen key was near breaking point before the service valve opened. And the hex hole was buggered up before I started. I suspect the service valve was leaking at the factory, so the QC guy tightened it as hard as he could.

Anyway, as difficult as it is for a cheap guy like me to admit, I think there is a point where it is time to condemn rather than patch a well worn tire. And that includes the copper pipes.

Part way into the project... Before photos.



Part way into the job.



I gutted the new air handler so I could get it down the stairs.



I hope I can recall where the bits go back. Tomorrow, I pick up the new plenum from the sheet metal vendor. Bad news for him is I have a fresh drawing for the next system ready to hand over.

The third system, which was the first one to fail two years ago is next on my list. It is still running after compressor replacement, but I know I am on borrowed time and paying excess operating costs. I plan to swap it out for new gear while the copper that runs through the walls for that system is still acid-free.