The cold water pipe in my 2nd. floor bathroom is runninng hot water for a bit and then gets cold. I checked the pipes down in the basement. The hot water and cold water pipes are seperate. But, the cold water pipe feels warm on the vertical section going to the 2nd. floor, and then about 2 feet in each direction on the horizontal piping it is warm. BUT, it gets colder the further away you get on the same pipe (horizontally that is). This same cold pipe runs to the toilet and the pipe that extends to the toilet feels hot occassionally at the bottom of the toilet.