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Old 03-17-12, 06:46 PM   #1
SparkyAZ
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Default LG mini-split install project

Hi all,

I'm working on an LG mini-spit AC install for my garage/workshop. Last fall I completed the majority of it, pouring a pad, setting the outdoor and indoor unit, and connecting power, lineset, and control wire. Now all that's left is the final leak test, evac, and charge. This was a used unit that came out of service but appears to have been in working order (the price was right for the unit). It was pumped down so the refrigerant should be inside the unit but I have no idea how much is there. Prior to stumbling across this forum, I was going to have a mini-split A/C guy to do the final hookup. That's still on the list - the guy we contract with to do our mini-split A/C at my workplace owes me a callback on Monday. Since we just installed 3 new units at work, I'm hoping they can give me a deal

At any rate, I still would like to get the 'stupid/easy' stuff out of the way so as to not burden the A/C guy with trivial stuff like finding leaks in my first-attempt flare fittings...

A couple questions for the mini-split gurus on this forum, dumb ones first:
- are there any issues with using a small amount of teflon pipe seal compound (pipe dope goo) on the threads of the flare fitting? And by this, I mean on the male threads only so it gets pushed back and away from the fitting by the compression nut, and only a small amount such that it doesn't contaminate the flare face or get inside the fitting. Is there any issue with this compound reacting with the R410a refrigerant? I've used it before on threaded compressed air fittings and threaded plumbing fittings, and it seems to work well once it sets up. I see there is a blue Nylog sealing compound normally used by those in the HVAC trade. I'm not opposed to buying some of the Nylog, it's readily available on ebay. Its just that I don't have any of it now and I do have a tube of the Teflon stuff.

- thoughts on installing an external drier in the lineset? Since this system was pumped down and closed off prior to the lineset being cut and the system moved, I'm hoping there is not any moisture in the system, but I have no way of knowing for sure. This unit was in Arizona all of it's life, and it's pretty dry here. Still, I don't know if there is any other 'crud' in the system that should be filtered out, All I know is there is 'some' refrigerant in there, I have no idea how much or what condition it is in. If I do this, I'll have to buy one as I don't have one. The unit has a 1/4" discharge line, I presume that's where these normally go in-line (based on the photos I've seen on this forum).

The rest of the install looks pretty straightforward from there. I'm going to borrow a N2 tank from a friend who does paintball along with the associated regulators to bring the pressure down to 100~125psi. I will probably have to adapt whatever fitting they have on the output of the regulator to a 1/4" flare, but I suspect I can find the required parts at Home Depot or the paintball store. Then to find/borrow a vacuum pump, buy some vac oil, micron gauge, etc, etc! First things first, though pressure test - no leaks!

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Old 03-17-12, 09:18 PM   #2
BradC
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Quote:
Originally Posted by SparkyAZ View Post
- are there any issues with using a small amount of teflon pipe seal compound (pipe dope goo) on the threads of the flare fitting? And by this, I mean on the male threads only so it gets pushed back and away from the fitting by the compression nut, and only a small amount such that it doesn't contaminate the flare face or get inside the fitting.
Yes. Don't do it.

Nylog is made from refrigeration oil. Blue is synthetic, Red is mineral. You have no idea what the carrier is for the Teflon goop, and what it might do when it contacts refrigerant.

A flare joint is based on the compression joint between the copper and the brass. Just put a drop of oil on the back of the flare to stop the copper binding on the flare nut and call it good.

I've done *loads* of bum flares that leaked. I showed a couple of them to a local refrigeration guy to get his take on it and he pointed out my very obvious mistake. I was not properly and completely de-burring the end of the tube prior to making the flare, so the seal was between the brass fitting and the rolled edge of the tube rather than the flare face.

This had a two aspect cause. One, I was over-tightening the tubing cutter to get the tube cut quickly. This compressed the end of the tube. Two, the resulting burr was not being completely cut away because of the way I was using the tool.

Since I learned to properly cut and de-burr the tube my flares have been textbook.

Yellowjacket have some great videos on using their tools.

Download and watch this video a couple of times. By the end of it you'll be making tight flares.

Tubing Tools Techniques Training Video - YELLOW JACKET UNIVERSITY

I use a drop of oil on the back of the flare, and I also use a drop of oil on the flare tool when I'm making the flare. That's all.

I have both types of nylog, and nylog will help seal a bum flare. The problem is over time it eventually leaches out of the joint and the flare leaks. I'd rather have it leak *now* than later.
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Old 03-18-12, 12:12 AM   #3
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Thanks, Brad! I guess if they make a 'special sauce' for the job, it must be for a good reason. I take it the blue synthetic type is compatible with 410a and the red mineral is for older refrigerants?

Thanks for the link to the Yellow Jacket videos. I happened to use a new mini-tubing cutter and tri-blade deburring tool on this project (made by Superior Tool, which look remarkably similar to the yellow jacket versions). The flaring tool was also a Superior Tool product, but I'm not sure what the cone angle is, probably 45 degrees not 37. The multi-size auto-adjusting tool in the video looks pretty slick. I guess if I have a leak I may have to add another tool to my collection

I agree about finding a leaky flare sooner rather than later. If I can get away with just a bit of refrigerant oil on the flare that would be best. I noticed there was no 'goo' residue on the flares or hardware from the original installation, but that brings up another issue in that the fittings on the unit are not 'virgin' at this point, but they did look to be in good shape when I installed the new line set.

I'll probably leave it under pressure with N2 for a while to see if there are any slow leaks, since I won't really need to use the system for another few months. My experience with plumbing has taught me to always use the teflon pipe goo on any threaded fitting. It always seals first time and even if there is a small drip, once the teflon sets it will seal. I have fittings that have been leak free for well over 10 years with the stuff, but flares are a different animal and this is my first attempt.

Last edited by SparkyAZ; 03-18-12 at 12:34 AM..
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Old 03-18-12, 04:36 AM   #4
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Quote:
Originally Posted by SparkyAZ View Post
Thanks, Brad! I guess if they make a 'special sauce' for the job, it must be for a good reason. I take it the blue synthetic type is compatible with 410a and the red mineral is for older refrigerants?
Yeah, although the blue is pretty universal. It certainly won't contaminate mineral oil systems, and is supposed to be good for both.

All my systems at home are mineral oil, so I just use the red mostly.

I have a gallon of Vac pump oil, and a 4L of Suniso 4GS. I generally use the 4GS on the flares. Vac pump oil is excellent for maintaining your o-rings, hose and fitting gaskets and fridge tools in general.

I have some dropper bottles I bought from an Aromatherapy store on E-bay. They have nitrile bulbs and glass droppers and are excellent for oils and alcohols.

Quote:
Originally Posted by SparkyAZ View Post
Thanks for the link to the Yellow Jacket videos. I happened to use a new mini-tubing cutter and tri-blade deburring tool on this project (made by Superior Tool, which look remarkably similar to the yellow jacket versions). The flaring tool was also a Superior Tool product, but I'm not sure what the cone angle is, probably 45 degrees not 37. The multi-size auto-adjusting tool in the video looks pretty slick. I guess if I have a leak I may have to add another tool to my collection
I hope your flare tool is 45 degrees!! Most of my cheap Chinese tools look remarkably like the Yellow Jacket ones. I suspect they come out of the same factory, however without the extra finishing and QA/QC steps.

I have a tri-blade deburring tool, but I've recently taken to using a single blade one. I find the single blade tool gives a better finish. When I use the tri-blade tool it seems to chop up the edge of the pipe quite a bit. It's probably the way I use it though.

Quote:
Originally Posted by SparkyAZ View Post
I'll probably leave it under pressure with N2 for a while to see if there are any slow leaks, since I won't really need to use the system for another few months.
Yeah, great idea. I have a fan-coil in my roof that has a lineset on it at the moment. The "outside end" of the line-set has the 3/8 tube brazed shut, and the 5/8 tube has a service fitting brazed to it. I put 400PSI of N2 in there when I installed it and I check it every couple of weeks. It'll be probably 6 months before I have that unit connected up, so we'll see if there are any more slow leaks in the coil itself (I picked it up at the scrap yard for $20). When I first pulled the coil out, after re-plumbing it (building an inlet distributor to replace the cap tubes) I put 300PSI of N2 in it and chucked it in the pool. I very quickly found and fixed the obvious leak.

I use teflon tape on anything plastic, and Loctite 567 on metal-to-metal threads. They never leak. Flares are not about the thread though. Lubricating the thread can help you get it down tight enough, but usually just the back of the flare to stop the copper galling on the nut.
The other thing about plumbing is they are rarely subject to continuous pressures exceeding a couple of hundred PSI. Gas is pretty slippery when you squeeze it hard enough.

If the person who removed the unit properly pumped it down and your line set is not too far +/- the length of the original line set (give or take a couple of Metres) then you should be able to just let 'er rip.
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Old 03-20-12, 01:15 AM   #5
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So I went to the A/C supply place that's not far from where I live this past weekend. Despite telling me over the phone that they wouldn't have a problem selling stuff to me, when I was there, the guy really did not want to sell me anything. I should have taken that as a hint.

Anyways, I picked up the 5/16 to 1/4 service port adapter I needed plus the blue bug juice leak detection fluid:

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Then I found this at the local hardware store, for much less than I paid for the big spray bottle :

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My flaring tool is the Superior Tool model from Lowes. Checking the cone angle shows that it's pretty close to 45, if anything a degree or two over:

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Here are a couple pictures of the install so far:
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Old 03-20-12, 05:08 AM   #6
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Quote:
Originally Posted by SparkyAZ View Post
Anyways, I picked up the 5/16 to 1/4 service port adapter I needed plus the blue bug juice leak detection fluid:
Tip for future. Water with washing up liquid makes excellent leak detection fluid if you spike it with glycerine. It's what is in the kids bubble fluid that makes the bubbles seemingly last forever.
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Old 04-19-12, 10:09 AM   #7
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Default Great looking install.

I just installed a mini-split and the 25' line set was factory flared but I didn't like to looks of them. I cut them off and mady my own (first time). I made the flare large so it barely cleared the threads of the cap. Mine also used small lines, 1/4" and 1/2". I used blue nylog on the backside of the flare to prevent binding and used Flaretite seals on all 4 connections. I torqued the 1/4" to 20NM and the 1/2" to 55NM. What I noticed is after it ran for a few days, I re-torqued the connections and they were much looser then the original torque. Maybe the Flaretites are compressing? I wanted to pressure up the system to 400 PSI but the manual said not to exceed 150 PSI. I ended up leak-testing at 200 PSI. Hope it's tight. Vacuumed down OK. Good luck with the install. It's worth the effort.
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Old 05-13-12, 08:21 PM   #8
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Default Project update

It's been a while since I've last posted, so time for some updates.
I finished the install but chose to punt on the final commissioning of the unit. I had no idea how much refrigerant was in the system or what the condition of it was, so I chose to call my HVAC guy to do a time+materials work on the final setup. He basically did what I did to double check the work (pressure test with N2, vacuum system, then weigh in the factory charge of R410a. Since the factory spec on the valves was no more than 150psi for the N2 test, and we were going to put in new refrigerant we decided to vacuum the system, open the king valves, then pressure test with N2 at 300psi to make sure all was good, re-vaccum and then weigh in the charge. In the process we found one of the flares had a v-notch split in it, so that had to be re-flared. My flares were a bit oversize, he made them much smaller. Also decided to braze in a high-side service port so we could check both liquid and gas side system pressures. At the end, we achieved a 32 degree F inlet/outlet temperature split at the indoor unit with an outdoor tiemperature of 102F. I was amazed at how quite the LG unit is. It's a dual speed outdoor unit, when it's running I can barely hear it from inside the house if it's perfectly quiet inside. Even outside standing next to it is not very loud. Much quieter even than my York split system on the other side of the house.

One unexpected thing we found was that LG installs a reversing valve in their straight-cool A/C mini-splits. So it looks like all I need to do is order the coil as a replacement part, slip it on the valve, and connect it to the wire harness which is right next to the valve and I have a heat pump. The relay is already on the board and wire harness present. Where I live it's pretty warm and this is for my garage/workshop so I'd only have use for it maybe a month or two at the most. But hey, for the $30 cost of the coil I think it will be worth converting over. A place called Appliance Factory Parts had the part (and it appears numerous other replacement parts for LG mini-split units).

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