Oh, and now the bad news. I just observed that the lineset
is leaking, right at the vapor-line flare nut.

Argh.

My guy is back here tomorrow anyway, and I guess he's
going to have a bit more work to do than finalize a couple
of ducts... what is recommended best-practice for a
really tight/reliable flare connection? Nylog-blue?
A particular type of flaring tool? With the lineset
length already cut and very little slack to work with,
is this fixable?

_H*