LG Mini Split Install question (regarding vac, pressure test, charging)

[velillen01]

Well tomorrow the last pieces I need to finish the mini split are coming. But I do want to double check a couple things.

I figure I will post the general procedure and how I understand it and then ask the questions at the end.

For reference the system is a
(1) LG 30k Multi Zone Mini Split (LMU300HHV)
(2) LG 12k Ceiling Cassette ( LCN128HV4-NG)

Now most of the install procedures and videos online for mini splits tend to be for a single unit (over a multi zone) and the main difference is there is generally only 1 service port. However the LG has a service port for both the gas and the liquid. Heres a picture (top is Gas bottom is Liquid)

So then the procedure. Which from the manual seems pretty simple but it also talks about connecting to BOTH the Gas and Vapor service ports.

So start with the nitrogen pressure test

Then the Deep Evacuation

And finally going to the charging portion

So now for questions....

1) Since the procedure is to do both the Vapor and Gas lines, do I do them individually? Or "T" them together? Or should I take my manifold gauge set (yellow jacket one) and connect the low side line to one port and the high side to the other and then do the test/vacuum through the "middle" line?

Really I guess that is my main question. I understand the whole procedure its just a bit different than most of the information you see online since it wants to use both service ports vs most information online uses a single port so want to double check!

Thanks in advance and sorry its a bit long of a post!

 

[formula388]

If I recall what I did was hook up my micron gauge to one side and my vacuum to the other. I vacced it down and made sure it was good then let the refrigerant out and went on my way.

 

[yeldogt]

The ports on the singles are typically in line with the head lines ..... that can't be the case with a multi.

Are you adding more heads ..... ? Is it rated for only two connected? What is the minimum output of the compressor?


With the multi -- the refrigerant is never fully off -- so you typically want all the heads on

 

[fitter30]

Never used medical grade nitrogen for ac work. Alway used regulator nitrogen from welding gas supplier. Usually nitro test 500 lbs for 12 hours with a 500 nitro regulator after pulling a vacuum just to rid of the air in system. Passes blow nitrogen evac through guage manifold break vacuum with nitrogen pull another vacuum, micron gauge on liquid port. 500 microns or less weight charge in. Pressure starts to come up valve liquid off pull micron guage finish charging.

 

[velillen01]

If I recall what I did was hook up my micron gauge to one side and my vacuum to the other. I vacced it down and made sure it was good then let the refrigerant out and went on my way.

Thats basically what I discovered. I played around a bit with the nitrogen charge and it seemed all the loops are "normally open" in a powered off state. So it didnt really matter if you "Tee" together or just do it all via one port.

Never used medical grade nitrogen for ac work. Alway used regulator nitrogen from welding gas supplier. Usually nitro test 500 lbs for 12 hours with a 500 nitro regulator after pulling a vacuum just to rid of the air in system. Passes blow nitrogen evac through guage manifold break vacuum with nitrogen pull another vacuum, micron gauge on liquid port. 500 microns or less weight charge in. Pressure starts to come up valve liquid off pull micron guage finish charging.

Im sure the medical grade i sjust a "cover your ****" things from LG. But thanks thats what I ended up doing for the most part!

 

[Milton Shaw]

The test pressure on the low side coil should limit the pressure you test at. If it max pressure is 250 -300 PSI why would you put 550 lbs on it. High side test pressure is that high but you are not testing for leaks in the high side, it's still full of refrigerant unless it came with a leak. What you are looking for are leaks only in the piping you installed not in the two halves of the mini split. And then those leaks are at the joints unless you have a one in a thousand hole in the center of the coil of tubing, like one I found in a coil of 1/4 copper from Home Depot for an icemaker.

 

[theoldwizard1]

Whether you are pressure testing with nitrogen or pulling a vacuum, if the system is "empty" shouldn't the pressure/vacuum be the same on either port ?

Good thing the zone valves default to open !

 

[hefnerconstructionlc]

Just did a couple of these very same systems this week.
The LGs are very particular would not suggest deviating from their procedure, other than using regular nitrogen. Getting ahold of medical grade dry, is almost impossible.

Double check valves closed.
Remove Schrader valves.
Install hose to gas side, install hose to vapor side.

This gauge set https://www.amazon.com/gp/product/B0036FAP5G/?tag=atomicindus08-20

3 of these to attach hoses to:

Amazon.com: Yellow Jacket 19173 5/16" Female Quick Couplers x 1/4" Male Flare : Automotive

Buy Yellow Jacket 19173 5/16" Female Quick Couplers x 1/4" Male Flare: Fittings - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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**** both sides down, simultaneously.
Purge with nitro three times preferable.
Will need the mini split service t-tool adapters from mini 5/16 to 1/4 and then a micro gauge.
This Tool

Amazon.com: Vacuum Charging/Core Tool, 5/16 In : Automotive

Buy Vacuum Charging/Core Tool, 5/16 In: Air Conditioning Line Repair Tools - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

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https://www.amazon.com/gp/product/B009AXGCSC/?tag=atomicindus08-20

Will want the tool to isolate the micro gauge from the lines when purging.

 

[hefnerconstructionlc]

Should look something like this. There are some good YouTube videos on the subject. Good luck.