DIY Mini Splits
#21
I was >< to installing a mini split system in the basement to my old house. I had all the planning done. I was going to do everything but the final connect and vac on the lines. I had an HVAC guy that was going to charge me 100.00 to do it and I knew it would be done correctly.
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#22
(05-06-2018, 08:38 PM)blackhat Wrote: They aren't compression fittings, 99% are flare fittings.  Flaring sounds easy but when you start hitting the 500 psi range they have to be right for a long time.  The unit connections are usually a unique thread, your standard refrig gauges and hoses don't fit.  You need at least one adapter.  You don't just need a vac pump, you need a vac pump capable of pulling a very deep vac, below 400 microns and preferably below 200 and staying there.  You can't measure those vac levels with a gauge set, you need a reliable digital gauge to verify your vac.  You most definitely should not use compressed air to pressure test your lines, it contains moisture and possible contaminants.  A nitrogen tank is the correct pressure test means.  Oh, by the way, you have to get a regulater for that tank. Now, if your lines are outside the factory charge limits, you need to weigh, within a 1/10 ounce, the additional amount of refrigerant required.  A bath room or kitchen scale won't do that.


There are a significant investment in specialized tools to do the job right. I would expect a tech to be on site roughly 3 hours.  $100/hr???

Thanks for taking the time to answer .... great explanation!  $300 sounds reasonable to know it is done correctly.

Crockett's $100 is even more so
Laugh
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#23
There are systems now that use the marine style linesets. Basically they are plug and play. The linesets have the correct amount of refrigerant in them. The fittings just screw together and when they finally meet they open the valves in the ends. 

       The issue is they are more expensive and are harder to find and the line sets only come in a few lengths and cannot be shortened. 

        The regular ones aren't a difficult install but if you don't have the tools like mentioned it doesn't make sense to buy them. The flaring tool alone is pricey, vac pump, micron gauge,nitrogen  tank and regulator, gaugeset, goofy metric adapter. That's the main pricey stuff. 

     I still have that stuff from back when I did commercial refrigeration and that said on my house I have a friend do the brazing and some other stuff cause he does it every day and I'm way out of practice. I'll do a min-split but not a regular split system anymore. And in the future I won't be doing any of it myself (other than shop stuff) as I'll have someone else do it and have them deal with it when there is an issue with it.
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#24
(05-06-2018, 12:49 PM)paarker Wrote: Has anyone installed their own, or is this something best left to the pros.

I have, what is your specific question?  Outside of the specialized tools and kinking the lineset, the installation was really straightforward. 

As others have written, you will need a vacuum pump.  I happened to find an inexpensive one on Amazon that works quite well (<$75 if I recall), but I didn't just buy it for this job, I also planned to use it for working on my personal cars when they need a compressor or other A/C part replaced (and as it happened, I had to replace my wife's condenser last summer), in the past, I had borrowed a coworker's vacuum pump, so this was my excuse to finally buy one for myself.  Then you also need a manifold set, these mini splits, at least the Chinese clone that I have, you can only connect the low pressure side, and as others have said, you need an adapter because mini-splits tend to have a smaller than standard fitting, again, Amazon was my friend.  Because I bought a Chinese clone, when installing, I actually kinked the line set even when I tried to be extremely careful with it (one or more of the ratings of the unit I bought actually mentioned the line sets seemed to be on the thin side and more than one person kinked one or more of their tubes), requiring buying more refrigerant tubing from one of the BORG's and having to get a flaring tool (get a set capable of making a double flare, its more forgiving than a single flare, DAMHIKT).  Since I wanted to elevate my outdoor unit off of the ground so I could use the area behind my workshop to store a flatbed trailer, I also built two supports since the ratings for the OEM supports for my unit were not rated very highly and most said they were made from thin metal, and I had to rent a duct jack to lift the unit.  Wiring up the unit was pretty straight forward, had some issues with leaks until I figured out that what I really needed was a double flare, once the system was able to hold vacuum for 24+ hours, I knew I got it about leak free as I was capable of getting it.  All of the refrigerant was stored in the outdoor unit, and all I had to do was open the valves per the instructions.  My unit, a heat pump, has been running for approx. 4 years without needing any refrigerant added.  I did have an error code for one of the thermostats, not sure which one (the service manual I found online for my unit was not specific for the code it only said one of the thermostats was not working), but I cleaned both that it could be (one on the condenser for outdoor air conditions and the other inside the indoor unit) and it has been working OK ever since.  I will say, that for most of those years, I have not used it for A/C in the summer because I have not run the condensate line outside to get rid of the condensate, mainly it was used for heating my detached workshop in the winter, I only started using it last summer for cooling.

For the most part, unless you have plans for future vacuum pump use, or can rent one (not sure if auto parts stores rent them), I would suggest doing 95% of the work yourself and then calling in a pro to do the final leak test, pull a vacuum and perform the startup.  If you insist on a full DIY install, then while I don't disagree with the person who says that you can't go by a manifold set to see how much vacuum you are pulling since you would need a gauge capable of higher accuracy, for all intents and purposes, if you leave the vacuum pump running for several hours to ensure you pull a deep vacuum and boil off as much water as your vacuum pump is capable of, you should be fine. Also, leak testing using compressed air vs. nitrogen, ideally yes, nitrogen is the way to go, I used compressed air because I have an air compressor and i used an airline filter.  I figured any moisture I introduced to the system would be removed using the vacuum pump and any oil vapor would have mostly been removed via the filter and since the system only used a very small amount of air to pressurize, the amount of oil in the system would be extremely limited.  

Good luck regardless of how you proceed.
Paul
Paul
They were right, I SHOULDN'T have tried it at home!
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#25
I've finished up a few DIY installs for people. All I do is connect the final run of copper outside and inside, leak test, evacuate, check the wiring to make sure it is connected properly and start it up and charge if need be per the manual (Line set length).

The installations are tedious but easy. Just follow the directions. DON'T kink the copper.
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#26
(05-06-2018, 09:46 PM)JosephP Wrote: Thanks for taking the time to answer .... great explanation!  $300 sounds reasonable to know it is done correctly.

Crockett's $100 is even more so
Laugh

Well, he  goes to church with my dad.   Plus, he knows I'd throw in a case of beer.  
Wink   There are other reasons too but I'd probably be told I've failed some  test so I won't list those.
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#27
Thanks for the help. Looks like I'd be better off finding a guy who has the right tools.
Fill your heart with compassion, seek the jewel in every soul, share a word of kindness, and remember; the people's what it's about.
Capt. Tony Tarracino


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#28
(05-06-2018, 08:38 PM)blackhat Wrote: They aren't compression fittings, 99% are flare fittings.  Flaring sounds easy but when you start hitting the 500 psi range they have to be right for a long time.  The unit connections are usually a unique thread, your standard refrig gauges and hoses don't fit.  You need at least one adapter.  You don't just need a vac pump, you need a vac pump capable of pulling a very deep vac, below 400 microns and preferably below 200 and staying there.  You can't measure those vac levels with a gauge set, you need a reliable digital gauge to verify your vac.  You most definitely should not use compressed air to pressure test your lines, it contains moisture and possible contaminants.  A nitrogen tank is the correct pressure test means.  Oh, by the way, you have to get a regulater for that tank. Now, if your lines are outside the factory charge limits, you need to weigh, within a 1/10 ounce, the additional amount of refrigerant required.  A bath room or kitchen scale won't do that.


There are a significant investment in specialized tools to do the job right. I would expect a tech to be on site roughly 3 hours.  $100/hr???

There are DIY units on the market that come with precharged linesets so that you dont have anything to evacuate.  Eg. https://mrcooldiy.com/  You are stuck with the length they come with and have screw together fittings.  So if the fittings dont leak you are great.  If they do....  well thats a whole differnet issue.

I looked at this last year really hard and in the end let a pro install a Mitsubishi. I decided it was a long term investment since I wasnt planning on moving and with that system I got a 10 year warranty and I with a major Mistsubishi HVAC plant about 75 miles from me I was sure that parts availability was going to be good if anything goes wrong.   Thats what worries me about the diy install units.  If something breaks 5 years from now will the company even still be in business?  Hopefully at some point one of the brand names will do it.  If you are only living somewhere for a few years it might be worth a shot.
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#29
Here is one company that has the pre charged lines.  The prices actually aren't bad considering you don't need any specialty tools. 

https://mrcooldiy.com/
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#30
After pulling vacume, and opening valves, did you measure pressures, or did it work fine?
I long for the days when Coke was a soft drink, and Black and Decker was a quality tool.
Happiness is a snipe free planer
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