Hopefully someone will post some pics...
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The box stores don't sell refrigeration flare nuts. Most of the minis I come across use metric nuts that are made from a CAST 'brass like' material and the ones from the supply house are sae sizes solid brass, and made in the USA. Never had a problem with either type.
Originally Posted by ga-hvac-tech
I have however had problems with long shouldered steel flare nuts supplied on valve assemblies, replaced with brass.
Admittedly I don't use torque wrenches but do try to use flare wrenches. I still want one nonetheless.
The real story on so-called "410a Flares"
I teach the installation and service classes for Mitsubishi Mr. Slim and City Multi VRFZ products. Here is the real story and why you DO need torque wrenches, or at least need to use them for a while as a "learning tool" to re-calibrate your "feel".
It is not the higher operating pressure of R410a that necessitates different flares, but the [U]wider operating pressure range[U] of a variable frequency compressor system. Because of the wider temperature and pressure range, the copper that is clamped between the two pieces of brass needs to have a larger surface area in order to maintain enough of the metals elasticity to prevent flattening, and eventually leaking at the joint. The nuts and male parts of the flare are the same as they have always been in our industry. We just used to make our flares in such a way that left us some tolerence for the nut to easily fit over the copper. Now we utilize the entire seating surface with the minimum possible tolerence.
Overtightening is the enemy of mechanical joints in a system such as this. It manifests in the worst possible way. It will pass initial pressure test. It will pass deep vacuum and vacuum rise test. It will then operate leak free for a period of time. I have seen them go as long as 14 months in service. Then comes the call. "It just doesn't seem to run as good as it used to." Nope. It's low on charge. And you find it, either tighten the fitting in question or cut it off and redo it, weigh in correct initial charge, and leave. They they call two weeks later because the next one is leaking. This goes on indefinately unless the flares are all redone at the same time and to correct specifications - including torque.
I too had been making and tightening flares by "feel" for decades. I can't describe what a horrible realization it was the first time I used a torque wrench. I had been grossly over-torquing my flares all along.
When the flares are formed to meet the VRFZ system manufacturer's specifications, and oiled and torqued properly, you can walk away with confidence that the system will remain leak free indefinately.
I hope this helps.
When I worked for the old-timer who really taught me a lot and encouraged me to get my state license, he would have boxes of flare nuts on the trucks. All welded driers would get cut out and flares put in. we discussing this once, and he said, if you put a weld in there, you have a leak. I responded, if you put flare in you have a leak. HA!
I weld everything, and I am glad I don't do AC, work with 410A, nor install those mini-splits with the flare pipe connections (though I did install a couple in my mom's guest house as a gimmie).
One thing that really does make me laugh, are the swedged, pre-flared copper pipe bits on the wholesale shelf that you WELD in - WELD-IN FLARES! LMAO
Originally Posted by herefishy42
They are VERY nice in certain situations.
I've found them invaluable for cracked flare nuts on flared TEVs where there isn't enough room to get a block and yoke in there after cutting the cracked flare off.
Originally Posted by jpsmith1cm
X2. Always have some on hand.
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Huh, that's a very interesting read. Saw an adjustable wrench somewhere that was also a torque wrench. Maybe I'll pick up one of those.
Then I guess I'll need to find out what the correct torques are for the various sizes of tubing.
Originally Posted by Jon MEUS DSG
I think flare tight has those wrenches. Just Google flare nut torque specs.
I chased leaks all day on a mini that the plumber ran the piping on. Only source of heat and an LG to boot. I really don't know crap about LG's. I sort of wonder why the hi side and lo side pressures are near the same. Couldn't be my Smans. (:-
Originally Posted by BBeerme
Can't remember the brand, but I had an interesting install on one of those mini splits years ago. The unit came with all of the insulation and instructions that were very clear that you had to insulate both the liquid and suction lines. Because the metering device was at the outdoor condensing unit (?). That could explain similar pressures you may have been seeing; just a thought.
Originally Posted by lytning
Correct, meters at outdoor unit, pressures read on the line were after it dropped.
Originally Posted by BBeerme
Any idea on the rational for that? Maybe less refrigerant in the system or 'better' management of the liquid refrigerant? I've always been puzzled why they do that.
Originally Posted by mason