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Old 10-13-2008, 04:17 PM   #1
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DIY install ductless mini-split system?


I may be putting a mini-split in my shop when it gets built. Since it's just shop heat, I need to keep the cost down, so I'd like to do the whole job if possible. Wiring, and bending and flaring tube, are a non-issue for me, and since these systems come pre-charged, I may be able to do it start to finish.

I am however concerned about the final refrigerant setup. What do I need to do to put the system into operation? Is it as simple as drawing the lines out with a vacuum pump and opening a valve?

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Old 10-13-2008, 04:23 PM   #2
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DIY install ductless mini-split system?


Quote:
What do I need to do to put the system into operation? Is it as simple as drawing the lines out with a vacuum pump and opening a valve?
I can't remember the brand (may have been Sanyo), but I read a brochure for a split unit that said you can just attach the lines with included compression fittings without purging the air. (They come pre-charged too). It was an A/C / heat pump.

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Wiring, and bending and flaring tube, are a non-issue for me
Good deal.. The refrigerant / line-purge aspect was the only thing that had me worried too. They definitely make some of those units DIY friendly. (Many come with pre-insulated, pre-cut, pre-flared, etc, etc tubing too.. makes it pretty plug-n-play).

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Old 10-13-2008, 05:20 PM   #3
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DIY install ductless mini-split system?


Hi there,

Yes you're suppose to vaccum both the liquid and suction lines and then open the valves to let the pre-charged refrigerant fill the line. Make sure there is no leak on the connection and on the tubing itself. Hope this helps.

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Old 10-13-2008, 05:28 PM   #4
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DIY install ductless mini-split system?


How much vacuum is considered sufficient?


(Or, how hard should I suck? :D)
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Old 10-13-2008, 05:49 PM   #5
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DIY install ductless mini-split system?


Hi there,

Haha...suck it until it's -20 on your low side guage or more if you have the time. You can't have too much vaccum but alot of ppl have too little. Hope this helps.

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Old 10-13-2008, 06:34 PM   #6
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DIY install ductless mini-split system?


You do know, that depending on what brand you get. They stop providing heat at 14F outdoor temp.

Unless you order it as a low ambient unit.
In which case they are good to 0.
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Old 10-13-2008, 07:39 PM   #7
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DIY install ductless mini-split system?


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Hi there,

Haha...suck it until it's -20 on your low side guage or more if you have the time. You can't have too much vaccum but alot of ppl have too little. Hope this helps.

GSIstore
If you mean the red numbers below the black Zero on the suction gauge, 20 (which really means 20 inches of vacuum)ain't gonna do it. You'll still have so much air and moisture in the system you'll be running higher than normal head pressure.

You have to get down to 500 microns, which is so low a suction gauge
can't read it. You need a micron gauge to read that low.

If you don't you will diminish the cooling and heating capacity of the unit.
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Old 10-14-2008, 07:32 AM   #8
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DIY install ductless mini-split system?


you absoulutly have to pull vac on line set. as soon as you remove plugs from line set it's exposed to air. if you don't have access to micron guage you can use vac pump and reg guages [r-410 needs own gauges],can't use r22 type. pull 30'' for 1/2 hour. if it holds after you shut pump off and before opening valves it's PROBABLY ok. if a licenced hvac guy doesn't sign off on this job you have NO warranty [read the small print]
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Old 10-14-2008, 11:02 AM   #9
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DIY install ductless mini-split system?


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you absoulutly have to pull vac on line set. as soon as you remove plugs from line set it's exposed to air. if you don't have access to micron guage you can use vac pump and reg guages [r-410 needs own gauges],can't use r22 type. pull 30'' for 1/2 hour. if it holds after you shut pump off and before opening valves it's PROBABLY ok. if a licenced hvac guy doesn't sign off on this job you have NO warranty [read the small print]
Pulling down for half an hour at what the guage says is 30" is not going to do it. If you pull down to 500 microns and it moves up to 1000 microns that means there is still moisture and air in the system. You would not be able to detect that slight a climb with coventional 410 A guages.

Keep in mind that 1"hg (vacuum) is equal to 25,000 microns. A 1000 micron movemet would not even register on a the 30"hg mark.
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Old 10-15-2008, 07:04 AM   #10
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DIY install ductless mini-split system?


i agree but this is a DIY forum. he doesn't know what he's doing and is not going to have access to that equip or know what the guages are telling him. he should hook everything up and have an ac guy do the startup. in the absence of that he'll prob be ok [or out a lot of $$ ] if he pulls a vac 1/2 hr, checks for leaks and then opens systemn.
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Old 10-15-2008, 01:36 PM   #11
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he ... is not going to have access to that equip or know what the guages are telling him.
Don't count in it. This stuff isn't exactly rocket science, and the equipment is available.

I also have a R410A heat pump system on the house. It might make some sense to have a R410A manifold around anyway.

That said, I may have an HVAC guy do the final leak test, evac, and startup anyway. I don't want to be without a warranty.
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Old 10-15-2008, 01:41 PM   #12
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DIY install ductless mini-split system?


Just wanted to follow up on my other post...

Quote:
Originally Posted by Me
I can't remember the brand (may have been Sanyo), but I read a brochure for a split unit that said you can just attach the lines with included compression fittings without purging the air. (They come pre-charged too).
... it was bothering me and so I looked it up. It wasn't Sanyo. It was a completely off-name brand. Probably not true either. Bah, false hope for an easy DIY install.

http://www.ac-world.com/proddetail.p...=68GWX1B&cat=9

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All Celiera mini split systems are equipped with self purging valves on the outdoor unit. There is no need for vacuum pumping the lines. This is an advantage over most other models available in the market.

Edit: Looks like people are buying 'em though.. celiera 18000 btu won't heat

Last edited by ScottR; 10-15-2008 at 01:44 PM.
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Old 10-15-2008, 02:04 PM   #13
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DIY install ductless mini-split system?


Here's one more my speed...

http://www.ac-world.com/proddetail.php?prod=55GWX&cat=9

It doesn't say you don't have to evac, but it says it comes with a free installation kit. Wonder how that works...
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Old 10-15-2008, 02:11 PM   #14
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Don't count in it. This stuff isn't exactly rocket science, and the equipment is available.
.

You are right, not Rocket Science.

It's HEAT TRANSFER SCIENCE an THERMODYNAMIC SCIENCE. And what you DON"T KNOW can hurt the equip.
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Old 10-15-2008, 02:12 PM   #15
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DIY install ductless mini-split system?


It also says they are relatively new to Nort America.

Mini splits have been around here for longer then I can remember.

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