Mini-Split install

[Tom King]

I'm putting this in the Shop forum for future reference because a lot of people use mini-splits in shops.

A pro installed mini-split lasted about five years because of a poor quality install.  I'm installing the replacement myself.   

One problem I see with mini-split installs is that the mounting plate is pretty flexible and every install I've ever seen has one side hanging away from the wall a bit.  You're only able to catch a couple of studs with screws through the mounting plate and often one is nowhere near one edge of the mounting plate so it flexes away from the wall with the weight of the wall unit.

Another problem is when trying to use a cleaning bag, it's impossible to get it tucked up behind the wall unit all the way around, so some gunk my end up running down the wall.

I made a mounting base for the mounting plate out of some scrap 2x lumber that was flat.  First I ran it down to 1-1/4" thick to flatten pieces that needed flattening.  Corners are not glued, but indexed with biscuits and screwed together.  The one board with old paint on it is flat and I didn't want to run that dirty side with any cutters, but it will be covered by the wall unit anyway.

This 1-1/4" thick base is screwed securely to wall studs and the mounting plate screwed to it with screws in the farthest corners.

The edges of the mounting base are tapered back at about 35 degrees so the cleaning bag with have somewhere to get pulled in tight around the back of the wall unit.

I'm using an LG as the replacement.  The LG mounting plate does not have supports for the Rectorseal arms to ease an install or an uninstall, so I cut the ones off the cheap Chinese failed unit and let them into the back of my wooden wall mount.

The towel is to fill the hole overnight where the old refrigerant lines penetrated the wall.  We'll use that same location for the new lines.  The drain line is in a different place, but luckily fall behind the next vertical outer layer of White Oak board on board siding on our house from where the old drain line was.

The new LG 24k btu units are much larger and heavier than the 18k Tosot unit.

More to follow, but we're busy with other stuff too, so this will be as I can get to it.  I will be lucky to get one step done a day.

[Jfitz]

looks solid.

I'm curious - what was it about the previous poor quality install that caused the unit to fail? was it the mounting bracket issue you mentioned, or something else?

[Tom King]

The failed unit was from a poorly executed flare connection.  The flared end of the tubing was one sided enough because of the bending from being coiled, so that one side of the flare was shorter than the other side.

Ready to set the inside unit tomorrow morning.  I can't make noise while puppies are sleeping, so it has to revolve around that.  I had to move over under the next outer layer of Oak siding for the condensate drain line, but got lucky for it to work this good.  

I had to chisel out some clearance mortises for the install shelf brackets.  Poor design to start with, but will know better next time.  It wasn't bad, but I should have done them when I was using a router yesterday.

I used these plastic rods to go inside the lines to make the tight bend coming out from underneath the house and going up behind the siding.  This was the first time using these and they are a lot less trouble than the mechanical tubing benders.  Worked like a charm.

I'll foam all the holes when everything checks out.

The Easy Bend rods that go inside the lineset lines made bending them like I wanted them worry free.

https://rectorseal.com/easybend-full-kit/

And some extreme bend testing:

 

[Tom King]

Hopefully, I will be back on this tomorrow.  I bought a recovery machine before the price hike and it came with a choice of two things out of a list.  Mini-splits have 5/16" connections, whereas regular heat pumps are 1/4".    The two free things came from the manufacturer-Appion.  All the tools and equipment I order from Supplyhouse come in a day or two.  These free "gifts" took a couple of weeks, but finally came today.

I was wanting the 5/16" valve core removal thing that allows you to take out the Presta valve and speeds up the whole testing and charging process.  The other "gift" is the hose.  These would normally cost about $89 each.  I bought the machine right before the price went up about $200 a short while back. 

Hopefully I don't need the recovery machine in this setup, but expect to need one at some point in the future somewhere.   Beating the price hike and the choice of free stuff made me decide to go with it now.

[Tom King]

Since this is my first time doing this, I'm trying to get around all the typical problems involved with them.  I would like it a lot better if the connections were brazed like regular heat pumps, but they come with flare fittings.   There are millions of them in use all over the world, so it's not like the flare connections don't work okay.

The problem with the pro installed leaking flare connection was that the flared end of the tubing was cocked over one-sided.

I used one of these tubing straighteners replacing the brake lines on a tractor and liked very much what it did.

The heat pump line sets are pretty soft copper tubing that comes in a coiled up roll.  It's not pretty trying to straighten it out having been coiled up.  I bought a couple of tubing straighteners in the 3/8 and 5/8 sizes used on this job.

They work like a charm on the smaller tubing and are easy to use.  The 5/8 takes more force and you have to help it against the curves but it does a great job.

I'm sure people that work with this stuff all the time have a good enough feel by hand, but knowing I'm not there, I appreciate some help.  Pictures are before, during, and after using it on the 3/8 line.  I want the lines to address the fittings perfectly straight and the only way I feel comfortable with achieving that is if the lines coming together are straight

 

[Tom King]

I'm sure more are put in without these helper brackets, but I like this better than a balancing act.  It went right in place.

These brackets now cost more than it seems like they ought to, but so does everything else.  If I had this experience with them to start with, I would have just made some wooden ones.  We have about six more of these to install over the next couple of years.

[Tom King]

It went right in place by myself.   It would have been easier with another set of hands, but it's in place now.  You have to look around the sides to see the wooden mount for it.

 

The rabbets in the mount allowed me to get the hanging brackets back off.  I think if I made some wooden ones I've have them removable with screws into the bottom edge of the wooden wall mount.

[Tom King]

Even though the lines built onto the wall unit have flexible parts, I used the EasyBender rods in them anyway to turn them down outside.

I felt for easy range of motion for the lines coming out from under the house, up and down, marked the extremes of their range and the middle to make the cuts for flare locations.  It's starting to rain, so I put the caps back on the lines and will probably need to wait until this system moves on through.  Maybe back on it tomorrow.  I'll slide some more insulation off these lines and straighten them farther down before making the flares.

[Tom King]

The plan is to blow foam pucks through the lines before they are hooked up to clean any debris from cutting and deburring out.  To start with, we threaded some strong thread through a couple of the foam pucks to put down in the lines before I deburr them.  Pulling them out after the operation should clear the lines.

These are sold by Hilmor for cleaning old lines.  I intend to just blow the plugs through the lines without the cleaning solution since I'm only interested in cleaning out dry debris.

This is some strong thread that Pam has for sewing canvas, straps, and such.  I'll put a little washer on the inside end.  

https://www.supplyhouse.com/Hilmor-Tools-HLP058-5-8-Foam-Puck-10-per-Pack

[Tom King]

Like so many jobs around here, this one is on hold for a few days.  I thought I had every metric flare nut crowfoot socket there was up to anything that I need on tractors, but in the set I have it only has even sizes in the larger ones.  Waiting on Amazon to get a 23 and a 27 here. 

Typically, HVAC installers use a torque wrench with an adjustable wrench type head on it.  I have plenty of good torque wrenches and have an aversion to using anything but a flare nut wrench on a flare nut, even these heavy HVAC ones, so I'll wait a few days.

I did to all the electrical hookups, which were really easy since I'm reusing the wires that were already in place from the failed unit, so I at least got something done on it.

I didn't want to cut and flare the tubing before I'm ready to put it together correctly.  Amazon says delivery Monday.

[Tom King]

This last flare nut crowfoot wrench came late yesterday, so I was back on this today.   The foam plugs worked like a charm after deburring as you can see in the picture as I drug one out, all the chips came with it.

I make sure the flare fits good before even running the nut on.  The tubing straighteners helped make this much easier.  I also went slow enough so I didn't make mistakes like flare the tubing before I put a nut on it.

Pressure test with Nitrogen to 300 psi has been holding for an hour, and no bubbles blown anywhere, so it looks like we're good to go with the vacuum after lunch.

Since they want you to use lube on the mating surfaces anyway, I decided I might as well use the sealant designed for the purpose on the flare mating surfaces, and oil on the mating surfaces on the back of the flared tubing and in the nut, but not on the threads to change any torque setting.  So far, I'm 100% successful making leak free HVAC flares and hope to keep that up.

https://www.supplyhouse.com/Refrigeration-Technologies-RT201BP-Nylog-Blue-Gasket-Thread-Sealant-Pack-of-2

The Navac cordless flare tool makes perfect flares, like factory made.  I'm glad I beat all the 35% price increases with all this stuff.

https://www.supplyhouse.com/Navac-NEF6LM-1-4-to-3-4-OD-BreakFree-Series-Cordless-Power-Flaring-Tool-w-NFG1-Flare-Gauge

 

 

[Tom King]

One thing I forgot to mention was after tightening the first flare fitting with a click type torque wrench, I changed to the old bending-beam style torque wrench.  I felt like I was overtightening with the click stop one.  It was a lot more comfortable using the bending-beam type where I could look at the scale and judge where to stop in the stated range.   The installation book gives a torque range for each size tubing.  I like it better being able to have some feel within that range.

When putting the Nylog Blue on just the mating faces of the flare connections, I cut some fingers off a Nitrile glove to smear it on with.  You can squeeze just a little bit out of the applicator bottle.  One finger tip covered was all I needed, so no reason to dispose of multiple gloves.

edited to add:   Rained out soon after lunch, but it's still holding nitrogen pressure like it is supposed to.  Will just wait to pull a vacuum and charge the system tomorrow.  The rain raised the humidity to maximum and where the outside unit is has full Sun now, so will be better on me in the morning anyway.

[wtnhighlander]

I appreciate you sharing these little details, Tom. Makes for a good reference, if I ever make the commitment to a split unit for my little shop.

[Tom King]

When I started this thread I didn't really think it would do anyone any good right now, but hopefully it will sometime in the future.  I wouldn't invest in all the tooling for just one unit, but we have several of these we'll need to be installing over a few years, and hopefully there will be some details that someone might get some ideas from.

For a one time setup, the Mr. Cool DIY ones are the way to go right now.  The investment in all the tools would never pay back for installing one or two.  

Also, around here HVAC contractors come and go, so there aren't any to depend on and they're all in it to get rich quick from people on the lake.

We have other cooling systems that we can use while I take my time with this one, but we were able to heat and cool our house with the mini-split that failed and liked it better for several reasons.  Our house is beyond super insulated.  The mini-split was quieter and more comfortable than the big old style heat pumps.  It was a bit undersized for the whole house though and ran all the time.  Even at that, it was a Lot cheaper to feed.  This one should be better still.

If it turns out to be undersized too, I have somewhere else I can use it and the stuff to move it with.

[Mark J]

How do you cool multiple rooms with one unit?

[Tom King]

It cools our whole house with a couple of small fans circulating it in a big circle.  It's a sprawling structure including all the dog complex, but it's way off the charts on being super insulated.  It's so well insulated that there is really no way to calculate any heat loss. When I added the last addition, that covers one end of the original part and wraps around the back, the house actually cost significantly less to heat and cool than before I added that addition.  A "pro" calculated that we needed a 3-1/2 ton unit just for that addition, but I tried it without anything and we never needed to supplement what we already had.

Pulling a vacuum this morning, it holds a vacuum just fine, but will not go as low as I would like it.  I purged it again with Nitrogen and pulling the second vacuum on it now.  I think as long as I've had the lines open they accumulated more than the normal amount of moisture and it's taking extra time to vaporize that.  Hopefully, the second Nitrogen purge helped that.

The white tables save a lot of bending over from just sitting stuff on the ground.

Thinking more about the torque specs on the flare fittings, having a range to be in was new to me.  I've torqued hundreds of bolts in engines and the guts of tractors, but those were always specified to one value.  I think there it some variation on what it takes for these flare fittings depending on the initial fit.  Since I took extra particular steps to get the flared tubing fitting the seat as good as I could, it took less torque to bottom that all out than if you were also trying to pull together a lesser well fitting match.

I never got to the click with the first click stop torque wrench because I felt like I was overtightening and didn't want to strip out the brass threads.  Switching to the old bending beam type torque wrench, every joint started to get tight soon into the range.  I think they don't tell you all the details about having that range.  No leaks with either pressure or vacuum, so I feel pretty good about that. I understand you want to stretch the threaded part a little bit, but not so much to overstress anything. 

In putting connecting rod bolts in an engine onto the crankshaft, you can get to both sides of the bolts, so the most meticulous way to set the torque of those is to measure the amount of stretch of the bolts in their length.  That's why people pay extra for the highest quality bolts in engine assemblies for racing engines or engines you just want to last longer.  

Edited to add:  I let it sit for a while later this afternoon, until all the equipment cooled off or warmed up, and it pumped right down without having to do a third Nitrogen purge.  Now that I have all the tools and won't have to wait for any to show up, I won't be leaving lines unsealed again on any other install for any time to amount to anything.  I will also order a second 5/16 presta valve removal tool for the other fitting on the outside unit, so I easily can do a Nitrogen purge before doing any pressure testing on any future installations.

The vacuum dropped so fast after that last little bit of moisture came out and held for over an hour, so I went ahead and charged the system.  It had been holding a good vacuum all day when I closed the valves and turned the pump off, so I decided I'd rather have it sit overnight with a positive charge in it instead of a vacuum.  Vacuum went down to 80 microns pretty quickly and held,  but I'm not sure the micron gauge is that accurate.   I don't think it can get any better than that.

Charging is the easiest and fastest part.  No bubbles on final bubble test after the charge, so we should be good to go in the morning.

This is the lowest model in the Fieldpiece vacuum pump lineup.  I don't see where anyone needs a better one.  It's really a well designed thing to operate and seems to work wonderfully.

[Tom King]

All hooked up and running great.  Feels like we could make ice.  It's very quiet and capable of moving a Lot of air.

I just need to figure out the European remote.  It can be operated by my phone over Wi-Fi, but I'll worry about that later.  This remote is so new that LG doesn't have anything about it online yet and the instructions in the unit installation manual are for some older model.  I figured out how to get it in cool mode and control the temp and fan speed, so that's good enough for now.

The outside unit is quieter than I thought one could be and the amount of hot air coming off of it is WAY over what the old one moved.

This is the system and supplier:   https://www.supplyhouse.com/LG-KSSAL241A-24000-BTU-R-32-23-SEER2-Art-Cool-Premier-Single-Zone-Inverter-Heat-Pump-Package-w-Built-In-WiFi

I had ordered it before the price increase.   Qualifies for 30% tax credit.

[Coop]

COOL!!!

Well done! 

[Tom King]

Putting all the HVAC tools up this morning, I played around with some scraps of the new Isoclima tubing and the old stuff that was probably cheapest Chinese.  There is a noticeable difference.  I didn't put a mic on them, but the Isoclima feels a little thicker, some softer, and just all around nicer stuff.  I feel a lot better about a flare of it compressed against the seat.   Even the insulation is multiple times better.  I'll be sticking with Isoclima linesets even though they cost several times as much as the cheap ones.  I have enough leftover length of these to use at our next installation at the rental house.

The instructions don't address doing anything with the access ports on the small/liquid/high pressure side(called all those things but they're talking about the same thing).  Everything is shown to be done through the large/vapor/low pressure line.  The instructions and all the youtube videos say to pressure test it after all the flare fittings are done.  Of course, you can't pressure test it without doing that, but next time I'm going to hook the Nitrogen tank up to the big line, just like needed for the pressure test, and circulate some Nitrogen through the system as I'm getting the small flare fitting at the outside unit done, after doing the inside unit connections first, or better yet another valve core removal fitting on the small side port.  That should help flush moisture in air out of the system and the only extra cost would be a little Nitrogen.

Nitrogen is cheap.  I carried my 40 cu. ft. tank back to swap out for a full one and the cost was $20.55.    It seems to me flushing to start with before the pressure test should be worth the trouble, especially since I ended up doing another Nitrogen flush anyway on this one.  It doesn't make a lot of sense to me to pressure test it with moist air in it.

If I hadn't done that flush, I don't know that I ever would have gotten the vacuum below 500 microns.  I couldn't get it down to 500 before the flush, but after running a couple of pump down cycles (letting it stop to rest and equalize between pump downs), it dropped like a rock towards the end and went down to 80 microns.  Recommended is to get it to 500, but the lower you get it, the less other stuff will be in there when it's operating and supposedly makes everything last longer.  80 microns is a really deep vacuum.  0 is a perfect vacuum, but that doesn't happen.

I've never seen an air conditioner work as good as this one is.  The air is not only cooled as low as Pam can stand it running on middle fan speed on a 91 degree day, but it's just much nicer to breath since it's also lowering the humidity in the air.  The old one drip, drip, dripped out of the condensate drain outside.  This one is running a steady little stream of water.

[Tom King]

This thing is Awesome!!

We've had extreme heat.  It was 100 yesterday, and 96 today.  I've been playing with this mini-split just to see what it would do.  It's been 70 degrees inside the house today, and is right now right past the hottest part of the day. 

It keeps up with KWH used, and says it's used 126 so far this month, which is 12 days since I got it running.  It says the cost is about $27.

Even when it was 100 yesterday, the highest it got in the house was 71.  It didn't run wide open all day, but I did have it turned all the way up by the end of the day yesterday.  Still trying to get a good handle on what it can do beyond simply setting the thermostat at a number.

Not only does it stay as cool as we want it (colder than Pam wants it), but the air is really nice to breathe.  The dogs have been laying around these hot days and don't want to go outside.  I have to make them go out when they do and they are glad to come back in.

Our house is a big sprawling structure, not laid out anything like a normal house because we have the big dog complex across the whole back of it.  Two 20" pedestal fans keep it circulating around the whole inside, and this is the only AC we have running.

When I was first researching about these newer refrigerants, using R32 in this one, it said that R32 had more cooling capacity than previous ones.  I believe it's noticeable now.

This is my first experience with high SEER units too.  This one is 23 SEER, and if what it says about cost is correct, not even figuring in the 30% tax break, it will pay for itself quickly.

[Ron Swanson Jr.]

That's great Tom. Good to hear!!!

[Coop]

On 6/25/2025 at 4:37 PM, Ron Swanson Jr. said:

That's great Tom. Good to hear!!!

+1

[Tom King]

Our electricity bill for the month since I installed this was almost exactly half of what the same month was last Summer and this Summer has been the hottest ever here.

I upgraded a few things in the installation kit since doing this one.  The flare nut crowfoot sockets I ordered off Amazon didn't exactly satisfy me, so I searched for some Tekton ones that I like.  Turns out Supplyhouse, my main supplier for HVAC stuff had the Tekton ones in stock.  I don't know why anyone would need these oddball sizes from them except someone installing mini-splits, so I guess I'm not the only one OCD about perfection in installing mini-splits and there is some demand for them from HVAC pros.

https://www.supplyhouse.com/Tekton-WCF16227-3-8-Drive-x-27mm-6-Point-Flare-Nut-Crowfoot-Wrench

I did find a deburring tool that I like off Amazon.  It's used in a drill and does what I want one to.  It makes perfect deburred ends fairly quickly.  I'll just have to push the foam plugs down a little deeper into the tubing, but have angled picks that I can easily grab the heavy thread with. 

https://www.amazon.com/dp/B00DYFQC5U?

 

[Tom King]

This finally got a good test for heating last night.  It got down to 26.  I got up before sunrise to go feel how the air felt coming out of this mini-split.  It was as hot feeling as any heat pump air I've ever done the back of the hand skin test and probably hotter!   The house stayed comfortable all through the night. I don't know how much it ran, but it handled it with no problem.

It ran some last month for AC and heat maybe a couple of times, but our electricity bill was the cheapest I ever remember it at $123.  That with two water heaters, two litters of puppies that require a lot of extra laundry, the barn and one small shop building.

I'll be sticking with R32 and high efficiency units.