Quote:
Originally Posted by AC_Hacker
I installed my mini-split.
My units came pre-charged... the charge was all in the outside units. .. the flair fittings. Then I torqued the flair nuts on per the installation instructions. I used a torque wrench to do this.
Still need to pull a good vacuum, though. -AC_Hacker
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There are other choices available instead of traditional flare coupling ,as well.
=> LEAKAGE FREE SAE CONNECTORS ,where no wrench needed.
-Helium tight ... max. leakage He 0,5g /10years !
Question:Any need for pressure testing of the line?
Nut connection SAE
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Before my reincarnation as a human being(?) I made some simple calculations in terms of the
reasonable moisture prevention since the modern mini-splits do not have any dryers!
The target was "how to avoid need of vacuuming" and still be on the safe side rgd. the max. moisture burden the system could swallow without long-term problems.
Below my calculations (not comissioned under influence of buse):
Assuming Rough H20 BURDEN in a commercial system of 2,5 .. 3,5kW as follow:
Original H2O in system in "standard state"
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R410a 1000g => 10 mg H2O (max. allowed H2O 10 ppm)
POE-oil 300g => 15 mg H2O (... " ..... " ......... 50 ppm)
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Purging alternatives ... pipeline 2x7,5m=>volume 0,5 litres
Propane (R290) 0,5 litres => 1/100 mg H2O (max. allowed H2O 10 ppm)
Propane (95%) 0,5 litres => 0,2 mg H2O (max. allowed H2O 200 ppm)
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AIR 0,5 litres => 7,5 mg H2O (+15degC, 15g moisture in 1m3 of air)
There is the basic question left:
WHY on earth solely vacuuming recommended for the installation of Cu-pipelines,if they are dry ,bright inside and capped at opposite ends prior to installation?
The quantities of moisture in the installation pipeline after purging for ex. BBQ propane (95%) is only 0,2mg vs.max.15mg H2O drifting/cruising in POE-oil.
Eventhoug the purging is not 100% complete there is a lot of H2O "dryer-capasity" left in POE-oil before facing the allowed max. standard levels.As far as I know the moisture tolerance on the system level is as high as 100ppm for H2O.
The vaccuming itself is not 100% proof either!It could be done ok or very ok!
You may say there could be some unvisible moisture left in the pores of pipelines prior installation in spite of proper purging.VeryTrue!
This could be "easily" avoided by domestic means => the Cu-pancake coil into the stove/Sauna ... +>100degC or so (simultaneously under purging-mode to prevent oxidation, N2 is safer but BBQ is ok if you know what you are dealing with).And after that,flatten the ends of the the tubes (gas still inside) and go to your installation site!
PS:
The pressure test could be done by BBQ-gas as well.Only raise the temp in the tank upto +40degC => then you get abt. 15bar out!
Patent for this is pending ... de..pending on financing ...