Terpene synthase that catalyzes the biosynthesis of the terpene valerianol. (2E,6E)-farnesyl diphosphate + H2O = diphosphate + valerianol Binds 3 Mg(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family. Extended N-terminus.