We just got home from a weekend away. We actually dropped the house temperature while we were away from 70 C to 58 C (outside it was actually the coldest its been all season (-30 C) When we got home our Kitchen Facet - which is a single knob facet - wasn't working properly. When I ran it on cold water it runs normally - when I turn the facet to hot water the water shuts off completely. Could it be that our hot water line froze? Every other facet in the house works properly - so it isn't the hot water tank. Any suggestions before I call a professional?