Ok so the jist is the company installed a new 60 ton condenser and evaporator for an older existing AHU. Not a big deal, except it was the plumbers who did the install. I came in at the end to do the final checks you know the pressure test/leak find and repair, vacuum and decay test then charge and commission. So 2 circuits on this unit and 1 of them is making me bang my head on a wall.
Well I'm f**king lost here. I can hold a 500 psi test over 3 days and lost a whole 2 psi which means nothing really cause that could just be my gauge, or the temperature difference (was 28 celcius when started, was 6 celcius when completed) so nothing special.
Vacuum down to 200 microns, but the decay test after 4 hours was at 5000 microns. So nitro purge and repeat. Same thing happened. Did a refrigerant purge and repeat, decay only went to 3000 microns after 6 hours.
Did the purge a repeat rotating between nitro and refrigerant 5 f**king times getting under 250 microns everytime but after 4-6 hours it's always over 1500 microns.
WTF am I missing here. It cant be a leak as I've swapped gauges, vacuums and even micron gauges. 1 circuit is fine and has been holding 750 microns for 2 weeks now but the other circuit just wont stay down. I've sniffed it, soap checked every joint, fitting and valve, and even gone well above pressure to try and find a potential leak as well as changed the replaceable drier core. So unless theres a puddle of water somewhere in this line I'm lost.
Any ideas or something worth checking?
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