Multi-zone MRCOOL project

[Mainiac Mat]

I'm taking a deep dive into mini-splits and MRCOOL DIY. I'm installing:

1. A multi-zone 27KBTU condenser with 18K air handler on first floor for LR, and 9K air handler for master BR on the second floor directly above LR. This installation is on the side of the house that everyone drives up to and I really want it to look trim and neat.
2. A single-zone 12KBTU condenser and air handler on the other side of the house for the first floor family room. This installation is out back and if it's not so pretty, I don't really care.

Though I have an acquaintance who runs an HVAC business who said he'd come out and evacuate/charge the system if I wanted to buy and install myself, I decided to go with the pre-charged DIY units and do the project 100% solo, as those guys are straight out and I suspected I'd have trouble getting him when I needed him. I also decided against buying the vacuum pump, flaring tools and gage kit and sizing the line sets exactly to fit. The reason I went this way was because my ceilings are 9' and the MRCOOL line sets come in 16' and 25' lengths. So if I'm very careful with the installation, I can hopefully avoid a big loop of extra line set coiled up behind the unit.

I acknowledge this isn't the least expensive way to go and that I could have saved ~$500 or so bucks by buying the tools, but my reasons were:

• I couldn't find that many DIY models out there that are multi-zone units, while MRCOOL has several configurations. This may be because I didn't look hard enough, but the supply chain crunch affected my options, as I waited until too late in the season and many of my options went up in "not in stock, no back order" smoke.
• I wanted to maximize my odds of having a successful installation.
• I found a large dealer that was about to receive a huge order of the Gen IV MRCOOL units, and they had the sizes and configs I wanted.

I came across a recommendation for Ingram's Water and Air Equipment as the lowest price MRCOOL option out there and though inflation has definitely driven the prices up, this was quite a bit lower than what was available on Amazon and I could one-stop-shop.

It's going to be an expensive and time consuming project, but I'm pretty psyched to finally take the dive and be done with dragging our 20 y.o. big **** window units around each spring and fall (though at least one of them will get installed in the new garage attic room). I'm also very much looking forward to NOT listening to the compressors endlessly droning on, as by all accounts, these mini-splits are very quiet.

So onward and upward with the installation blog.

I'll start with the invoice, so you can see what this setup costs and compare prices. Let me know if you think I could have done better somewhere else.

 

[Mainiac Mat]

I had the order shipped LTL freight to my place of employment, which is in a no sales tax state (Live Free or die baby).

My first question for anyone with experience installing mini-splits is whether or not I can run both line sets into the same 4.5" MRCOOL line set cover. I've done a dry fit and it appears that I can, but it will be very crowded by the time I get the power cable and condensation hose in there. Anyone out there ever try this?

If possible, I'd like to avoid it looking like this.....


Another concern is the condensation lines, as I need to have a horizontal run to avoid my basement bulkhead door, and don't want the condensation slowing down, pooling in the lines or backing up... then freezing in the winter. Any thoughts on the condensation lines?

 

[kbeefy]

I just ordered a 36k from 'skipthewarehouse.com'.
I got 3x 12k handlers and 6 line sets, I'll be running between 8' and 57'.

Good luck!

 

[fitter30]

Any extra pipe that is shorten by loops should be loop in the horizontal plane to keep oil from trapping. Never dealt with Mr Cool but they have been around for years.

 

[kbeefy]

Any extra pipe that is shorten by loops should be loop in the horizontal plane to keep oil from trapping. Never dealt with Mr Cool but they have been around for years.

Thanks, I had planned on looping it vertically.

 

[Mainiac Mat]

Any extra pipe that is shorten by loops should be loop in the horizontal plane to keep oil from trapping.

That's excellent advice that I hadn't even considered. Thanks for posting.

 

[Chris Holder]

i installed a 36K BTU MR Cool DIY from Ingram's about 5 years ago. It has worked pretty well, although I have had to have the line filled a few times (3-4) over the years. I the condensation line cracked from exposure a year ago. Worth noting for your install, especially if it will be a difficult run.

 

[428PI]

I think I paid around 2500 for the same setup from Pioneer. I got a 16ft line for the short one and 33 ft for the 18k unit I mounted on an inside wall. Didn't have to mess with any flares, and only used a vacuum pump and my brother had a bottle of nitrogen to clean out lines and check for leaks. Got 450 bucks back from local utility company for install. Spent some on electrical though and some tools to drill holes and bend larger pipe.

 

[Mainiac Mat]

Phase one (the larger part of the job) is done and the 27KBTU dual zone system is installed and running.

Here's some pics with material details for the electrical part of the job.

Wall bracket and hole (need a 3.5" hole saw)


Wall hole sleeve and flange (trimmed to fit clapboard). Here you see the line set, condensate line and communication cable.


18K BTU air handler on living room wall (above LPG Rennai heater)


Excavating for pad (had to transplant multiple Hosta plants, dig out garden soil & back fill with stone)


Pad formed and sack-crete poured. I lined the front and end of the form with loose bricks to match the garden perimeter.


Condenser set. Later, I hammer drilled 3/8" holes and used 2" Red Heads (expansion bolts) and the provided sound isolation pads to secure the unit.


This unit requires a 220v, 30amp service. From the basement load center I ran 10/2 Romex (remember to color the white line at both ends with a red Sharpie, as it is being used for L2).


Dilled through my sill and into the back of the 30 amp non-fused disconnect. Since I already have 30 amp overload protection at the breaker in the load center a fused disconnect is not required (and since it's outside exposed to hot/cold temps and humidity, is not desired).


From the disconnect to the condenser, I used the liquid tight flex conduit and fittings.


And here I am wiring it all up behind the condenser.

 

[Mainiac Mat]

I tidied up the line sets with the MrCool Line Guard 4.5" line set covers (which I intend to paint to match the clapboards, so they don't stand out quite so much).

 

[Mainiac Mat]

OK... some random thoughts....

This was a big job. Doing a single zone system at ground height would be a breeze, but the ladder work to run the second floor line set was a PITA. I took me ~35 man hours to pull it off.

The challenge was to get the line sets to the condenser with minimal excess, and to have them both roughly the same. From my perspective, having a coil of excess line is unsightly, and I've read that if your coil is vertical, you'll get oil trapped in the loops and degrade your system's lifespan. Despite my best efforts, I had ~4' excess on each line set, but they were the same length, so I ran them in a horizontal 'U' behind the condenser and will support that with a stake and zip ties, and before winter comes, I'll build a little "decklette" behind the unit to protect and conceal them.

So far we love the system, as it is soooooo quiet and can kick out the cold. We're just using the remotes for now, so I'll have to update the thread after I get the WiFi network and app figured out. The pump is controlled by an variable speed inverter, so the start up is very soft and gradual and when there's not heavy demand, it either shuts off or idles very quietly.

Did I say it was quiet? Both the air handlers and condenser are very quiet. Much, much more so than our old window units.

I'm burned out on the project and am way behind on several other chores and projects, so for now Mr. Cool is Mr. Done. I'll dive back into installing the stand alone 12KBTU set up in the family room on the other side of the house later this summer.

 

[Mainiac Mat]

Two things I almost screwed up big time....

1.) While up high on the ladder, my cordless drill fell off my belt and hit the back of the condenser. It bent the wire guard (which was easily bent back) and smooshed some fins. I am soooooo lucky it didn't rupture the tube and leak all the refrigerant out.

2.) I had the line sets connected and the supply valves open and then when the wiring was done I powered up the unit and went inside to test. Fortunately, before I turned on either air handler and generated a demand signal to pump refrigerant, I reviewed the installation instructions. I had not yet opened the "king valves" and if you try to run the units with no refrigerant, it's very likely you'll damage the compressor. So I quickly ran out and secured power, opened the king valves, re-did the leak checks and then proceeded to re-energize the condenser and go back in to test.

Read the instructions completely. There's quite a bit of repetition with warnings and such, and I glossed over the king valve part thinking it was just a carbon copy of the next zone instructions (which are redundant).

 

[428PI]

Good install. I was able to purchase some 10/2 wire from fb marketplace for half price and also used a surge protector at disconnect box. Just mounted my condenser on cement cap blocks so it's 8 inches off the ground for good condenser draining in the winter.

 

[reklund5]

wrong spot...sorry!

 

[bluedog225]

Thanks for the write up. Gives me hope I can pull this off. Solar install first.

 

[Mainiac Mat]

Quick update... I installed the USB network dongles into the air handlers and got the app working on my phone and am now able to turn the units on from work. Nice coming home to a cool house.

I followed the instructions to the letter and couldn't get connected. So I called the tech. support line and was pleased as punch that I got a live human in less than 5 minutes and they were able to get me all set up. Turns out you have to hit the LED button on the remote seven times to get the dongle to wake up.... not in instructions.

Overall, a very positive tech. support experience.