[Help] Came home from vacation and our pipes are frozen, no leaks that I can find. How do we thaw them?

Just like the title says. Water comes out at a trickle; hot water works fine I assume because the tank fills while we don't run it. We have a boiler & radiators, and I'm worried this will damage them if they can't refill properly. Any advice? I do not know where the frozen pipe is. We live in a multi-family home, and we thought one of the families were home and would run the water...but they were not and did not.

Submitted December 31, 2014 at 06:04PM by Originalfrozenbanana http://www.reddit.com/r/DIY/comments/2qwy5t/help_came_home_from_vacation_and_our_pipes_are/