gday guys,
like a lot of others i found this site whilst trawling the net for answers and have already spent substantial time reading previous threads!

i am currently installing a samsung dvm +3 system to a new office building under construction here in western australia.

the system comprises two rvxvht100ge (10hp) outdoor units with 16 neo forte wall splits and 1 mini cassette.

i have vacced the system out multiple times (about 10 times now) using javac (160litre) and cps (140litre) vac pumps with a pair of cps vg200 digital vacrometers. each time the system has had 15+hr evacuation and has had huge amounts of nitrogen put through it for pressure testing so its most certainly dry.

samsung have advised i need to achieve a vacuum that holds at 500micron for 1hr after switching off the vac pump.

i havent been able to achieve this level so far to date, the vacrometer rises over 1000micron at the +1hr mark so i presume there is a leak in the system somewhere.

i have charged a small amount of refrigerant as a trace gas and pumped up the pressure to 400psi with dry nitrogen for leak detecting.

i have a javac d-tek electronic leak detector and have methodically checked every single pipe branch weld, every individual eev flares and the flares on each indoor unit.

i have found a few very small leaks which appear to be as a result of physical pressure on the flare nuts at the indoor units caused by the piping behind the unit.
the flares themselves were all ok, but i cut them off and redid them all anyway and then retested them all ok.

the most likely place for a leak now, as i can see it, is either on one of the indoor coils (factory side leak).

my next avenue is to cut the pipes in the ceiling space as they branch off to different parts of the building and vac and test each of the 4 sections individually.

cutting 1+1/8" pipe and then having to reconnect it later where it sits on the ceiling doesnt excite me.

for those of you who have had very small leaks like this on vrv/vrf systems before, how have you tracked the leak?

many thanks,

rob.