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Chaaru 01-26-10 12:58 AM

LG LMU245HV mini split 3 zone heat pump DIY
Folks, the thread by Xringer has at last tipped me over the edge to go ahead and try my own DIY install of our mini-split system.

I will skip the contractor part as the prices quoted to me were close to double of my equipment + parts costs combined.

The outdoor model which we bought is a LG LMU245HV

The indoor models for our evaporator are LMAN095HV X 2 (for our 2 bedrooms) and LMAN125HV X 1 (for our living room)

In our rated configuration, these units will have the following efficiency numbers

* Cooling
o EER = 12.5
o SEER = 18.7
* Heating
o COP = 2.6
o HSPF = 9.6

Chaaru 01-26-10 01:13 AM

Service manual for LMN245HV

Installation Guide

After a thorough research on what would suite our needs, we ended up with agreeing on purchasing a LG Heat Pump mini-split AC with 3 zones. This would meet all our requirements that we had and this unit was capable of heating as well as cooling. The specs look decent and efficiency was also great. This combination qualified for the 30% federal tax credit as well. Additionally this unit had the good looks compared to the off-white/cream looks of the evaporators of other models.

The Heat Pump Indoor and the outdoor units were bought online. These were shipped promptly viz Fedex freight and reached us in about a weeks time. It was a big pallet weighing close to 180 lbs. The shipping was free and it was dropped off in our garage.

The unit details are LG Outdoor unit LMU245HV and 3 total indoor units ( 2 - LMAN095HV and 1 - LMAN125HV). The units were packed well and there was no sign of exterior damage. After the package was inspected for damage it was signed-off and we decided to unpack it to inspect it for any defects. Fortunately everything looked good. Here are some pics

In the picture below you can see that one of the fastening screws (L1) is missing. I wasn't too happy with what I could consider a poor QC. Hope the unit itself works well.

NiHaoMike 01-26-10 10:21 AM


Originally Posted by Chaaru (Post 5568)

It looks like it uses an impedance source inverter since the PFC inductor is split into two parts.

Xringer 01-26-10 07:21 PM

Nice looking ASHP!!
Maybe by seeing how the Sanyo valves are set up, you can get a better understanding of the LG setup..
Hopefully, the systems aren't too different. (I'll delete these when they aren't useful anymore).

Here's a pic of the nitrogen pressure test hook up. (See Fig. 60a below).
If you remove the two brass caps, you can insert the allen wrench and release the R-410A.
That step is the last thing you do before final testing..
I think maybe both your valves (Gas & Liquid) are about the same as my wide tube valve.
(I only have one schrader valve and I think you might have two).
But, where my line-set connections on the right, goes up to the indoor unit,
yours goes left, inside the unit to a 3-way splitter. (2 of them).
(Note: The artist drew the valves upside down, Compared to my unit).
The 3-way type valve (right column) is like both LG valves.

The pressurized R-410A comes in at the bottom of the valve. When the valve screw-cylinder- is screwed down (CW), it seals off the R-410A inside the outdoor system.

I took a quick look at your install manual and it seems like the line-set hookup
looked more like a Sanyo, than it does your LG.. Is it an out of date manual?

Do you plan on doing a pressure test of the line sets?

"With the main valve closed (before R410A release), can I pressure test the system with the schrader valve (service valve) ?"

Yes you can. If a valve is opened, the refrigerant will come out of the outdoor unit.
So, always leave those in the 'shipping' posistion until the end of the install.

When you hook up the nitrogen bottle to pressurize, nitrogen comes into the schrader,
and flows over the top of the valve screw-cylinder and directly into the line-set(s).

When you pressure test, remove the other cap, so it's schrader will be tested too.

When you finish pressure testing (all 3 line sets simultaneously),
and want to vacuum the linesets, replace the other cap.
Since the schrader with allow outside air to leak into the lines. It's only designed to hold pressure inside.

Or, you could put the nitrogen bottle on one schrader and the gauge set on the other schrader.. :)

Are those factory cap-lines are really air-tight? You can do a quick vacuum check and find out.
If they are tight, then you can test each line-set as you install it.
Instead of trying to test all of them at once.

Chaaru 01-27-10 12:26 AM

Thanks Rich for the pictures and suggestions.

Your explanation about the valve design now makes sense.

I will open up the two valve covers and see what's behind them, over the weekend. The manual when compared to Sanyo and Mr Slim is poorly written, which has led to quite some confusion.

I do plan to do the pressure test with Nitrogen. With the LG valve design it appears that I just have to hook up my manifold gauge to the gas service valve and pressure the system which will pressurize all 3 line sets.

With the main valve closed (before R410A release), can I pressure test the system with the schrader valve (service valve) ?

Chaaru 01-27-10 12:41 AM

Here are the list of parts I ended-up buying for my install

Drain Hose
Lineset Tubing (25 ft) X 3
Condensate pump for LG
Wire Whip
Service Disconnect
Control Wire
R410A Refrigerant Gauges W/ Hoses & Manifold
Micron Gauge SVG2
Nylog Blue sealant
Robinair 15150 Vacuum Pump
R410A adapter kit
Robinair vacuum oil
Riser Base

Coming soon - some pics of the parts

AC_Hacker 03-09-10 10:36 AM

How's your install going??

Originally Posted by Chaaru (Post 5579)
Here are the list of parts I ended-up buying for my install...





Your install thread was vividly clear and was going so well, I'm quite interested to know how your install progressed.

Any possibility of an up-date?

Best Regards,


Beaker 03-26-10 07:05 PM

I am building a super insulated dome house, and I am considering a mini-split system. The whole dome will cool adequately with a 12K btu Window A/C in summer, so I don't need much capacity. I have heard of the mini-splits but have never talked to anyone who's used one for any length of time...if you could tell about your experiences with mini-splits that would be great!

AC_Hacker 03-31-10 10:29 PM

Mini-Split Experiences...

Originally Posted by Beaker (Post 6305)
...if you could tell about your experiences with mini-splits that would be great!

Well, I've use one for about a year...

I live in a small house (aprox 700 sq ft), built about 120 years ago, and never insulated until I moved in. My insulating project has spanned a couple of decades and several code changes, so I have upgraded my insulation procedure as I have progressed. I'm now realizing I'll have to remove some of the insulation I put in, in the beginning to meet code.

I'm currently layering rigid foam in the walls, sealing at every layer. Insulation is really important, no matter what your heat source.

So about a year ago I embarked on a DIY ground source heat pump, which is still in progress, and I got a small (3/4 Ton) mini-split to keep me warm while the GSHP is still in development.

I really like my mini-split...

Previously, I was trying to reduce my heating costs by reducing the area I heated using a Nat Gas furnace with forced air (scorched air).

Closing off vents and rooms that weren't in use didn't work so well for me because my furnace only has one rate of heat output, so it short cycled and blasted me with frequent gusts of hot air. Not a pleasant situation.

The mini-split I got is an 'inverter type' Sanyo, and it is able to evenly modulate it's heat output to suit the situation. It's quiet, comfortable and cheaper to run than natural gas. Not only has my gas use gone down drastically (I still have NG cooking and NG demand hot water) but my electric use is not much higher than it was before the mini-split. In fact my gas use is so low that some months the fee to be hooked up to NG is higher than the gas I use. I'm even considering going to Propane, because at the small volume I use, it might even be cheaper.

So far the mini-split has performed as advertised, and I haven't needed to repair or replace anything.

I installed it myself. I didn't think to document my experience. Another blogger here at Ecorenovator named Xringer installed his own, and I shared with him what I had learned in doing mine. He took lots of photos of his install and did a dandy write-up.

Hopes this helps...



Chaaru 04-05-10 03:40 PM

I am back to document my install
Folks, I have been busy with work and related travel, hence never got a chance to update this thread on my progress. In-fact there wasn't much progress at all. I just got a few things done over the past couple of weekends and plan to post the details of my progress.

I will restart where I had left off.

Folks who have left me PM's, I can't respond to you directly as I don't have enough posts (hopefully that will go away soon)

Xringer - I saw your note + post today, thanks for your explanation. I will follow your advise and document my game plan before I embark on the vacuum and pressure test.

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