PVA support keeps failing mid print

[adrianmudd 0]

Ultimaker 3, Xmas Cura tree support, Had a couple of models which really needed the tree support to bend in from the plate, both I ended up with having to to use PLA support which was quite hard to remove without leaving surface markings.

Both times swapping hot end to BB and re-calibrating  before trying print with the support in (brand new reel) PVA, bits of tree just separated, twisted, gathered candy in mid-air, dragged some around with the print head. fortunately can pause from home and clear up next day.

PVA just didn't seem to be adhering to previous layer

 

[Dustin 55]

Sounds like you need to dry your PVA... Its very sensitive to moisture.. 
Pictures of the print failure would also help

[adrianmudd 0]

First fail was open 3 months in dry room. second was brand new, Less than 2 minutes out of sealed pack when print started, same fail, just didn't adhere, roughly 14 hours into print.

Can't afford the waste & mess of prints that fail at 3am! Ain't staying up all night watching the feed with my finger on the pause button for each test.

Given it was NOT damp filament, I don't know what to try tweaking first; extruder temp ? flow rate ? Fans?

[Dustin 55]

again.. pictures tell more of a story of what happened.. 
Even as you have described im still leaning to wet material. 
Failing 14hrs into a print tells me its possibly humid in the room.. pva sokes up all moisture from the air like a sponge.