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mike mahan's picture

HVAC may be the only trade I haven't done. Should I attempt to install a mini-split unit myself? Any issues with the refrigerant?

Easy to do., probably the (post #215599, reply #1 of 6)

Easy to do., probably the simplest DIY HVAC job other than a condensing NG furnace.  

Onlly special tool  you need is a decent vacuum pump, under $50 on ebay.  .  N2 bottle is nice, but not needed.  *

Something like this from ebay is sufficient.  Good excuse to buy another tool if you do not have on.  You can even use your old car refrigerant gauges.

(wont paste the link, $45 ebay vac pump from 'greatshoppingday2012" or similar.

  IF mostly for AC, put th indor unit a couple feet from teh ceiling

IF mostly for heat, put the indoor unit a couple feet above the floor.

Hook up electrical per insturctions.

Oil all surfaces of the flare fittings, flares and thread both,  with POE oil, torque flare fittings to specifications.  This is a critical step to assure no leaks.

Have slight slope from indoor unit to outdoor unit of refrigerant lines.

DO NOT YET OPEN THE MAIN VALVE on theoutdoor unit. 

If you have an N2 bottle, you can pressure test at 400 psi prior to pulling the vacuum with dry Nitrogen

Connect vacuum pump, and pull vacuum.  I like to leave the vacuum connected on a warm day, overnight if under 40 F. If below freezing, heat the refrigerant lines to the indoor unit with a heat gun a couple of times.  This makes sure all the water vapor leaves the system..

Close the vacuum pump line but leave onnected to the shrader valve.  

Open the main valve, this lets the refrigerant stored in the outdoor unit to fill the entire system. 

Quickly disconnect the vacuum pump liine (a tiny bit of refrigerant will hiss out) and install the schrade valve cap tightly. 

You are finished, should work fine. 

* I have read of folks simply connecting the lines and opening the valves, but NOT recommended, your efficiency will suffer and unit may ice up internall and quit.

There are folks on ecorenovator.com who are evangalists for DIY mini-splits, yu could check that site out also for more comments.

PS:  If yu use a longer line (post #215599, reply #2 of 6)

PS:  If yu use a longer line than supplied with the unit (typically 15 feet) yu should add a few ounces of refrigerant and a tiny amount of oil, the mini-split insturctions will have details.  Extral line length not recommended as you need to buy expensive refrigerant and scale, etc. etc..

Thanks. A couple of questions. (post #215599, reply #3 of 6)

What sort of wrench do I need to torque the fittings? Any brands to avoid or favor?

Thanks.

Any flare nut wrench will (post #215599, reply #4 of 6)

Any flare nut wrench will work.  Can just measure the length and us a fish scale and pull and calculate torque, Length times force.  Open end or even crescent wrench will work if you have no flare nut wrenches. .

After years of torquing stuff, I torque flares by feel, stop just when I 'feel' the first yield point. About the only thing I ever use a torque wrech for is head bolts and maifold bolts into aluminum heads. .  

Would recommend following the mini-split instructionon torque vs. feel without years of practice (and having failed a few connections in the learning process)<G>

Brands (post #215599, reply #5 of 6)

The brands question was about the mini split units, not the torque wrench. Any you like or dislike?

Oh, misunderstood. Anyway, (post #215599, reply #6 of 6)

Oh, misunderstood.

Anyway, being ht cheapest is a bragging point, last mini-split I bought was off ebay - dsearched for size I wanted, ;hit 'price plus shipping lowest first', and took a chance on a Klimaire, had never heard of the brand.

It has worked out fine, good quality, no problems, surprisingly quiet. 

About $1k for 1-1/2 Ton, shipping included. Came right to door in 2 packages.