Yeah, in a given system if you could acheive a boiling temp of 150f you could raise the boiling temp by just loosing vacuum to get to the 170f equivalent but you would still have to apply heat to get a boil there. Just not as much as a 212f boil.
Gee, just think of all the money we could save on fuel. This will be the next step in the evolution of the home brewing system.
"Hey buddy, how much vacuum does yer system pull?"
Now we'll have to think up an acronym for a vacuum driven system.
Bottled: Kolsch, belgian Wit, Belgian dubbel, Edworts Haus Pale Ale
Seconday: We don't need no stinking Secondary