I have a job coming up where I'm going to have to open the system up, but had not thought about filter/driers on mini splits. Do you guys stick to the rule of putting a filter/drier on anytime you open a system, even if its a mini-split, or do you make exceptions with these smaller units? And finally, this is one of those systems with three indoor units to one outdoor unit. Would you put a filter/drier on every lineset leaving the unit, or just one since the gas is shared, and it should eventually all go through that one filter/drier sooner or later? I would like to just put the filter/drier ahead of it all, before the internal manifold, but they just dont leave any room whatsoever inside these things for anything extra.
Also, forgot to mention, an instructor at a NATE class was saying that once POE oil gets moisture in it, theres no getting it back out? Have you found this to be true, and if so, is there even any benefit of using a filter/drier on a 410a system? Oh yeah, forgot to mention, its R-410a if you hadnt assumed that :P