We're going through a nasty cold spell right now (-13F/-25C to
-22F/-30C) and it's expected to last for quite a while yet. And my
coworker suggested that I turn the main water valve off in the house
before I leave in a couple of days for a vacation.

I will still have my furnace running when we leave for vacation, but I
plan on having it maintain a temperature of 60F/15C while we're away.

Is turning the main off still a good idea? Also, should the furnace
be set at a little higher temperature while we're away when taking the
outside temperature into account? Thanks for your time and courtesy.