Don't worry about not having much experience in plumbing, but asking
questions on this newsgroup. We live to serve folks in situations like
Somewhere there's a cross connection between the hot and cold water pipes.
What this means is that when you open the cold side of a faucet, it draws
out of the hot pipes too.
My first guess is that in the dishwasher room, there's probably a rinse
sink with one of those faucets that has a long spray head on a springy type
of spout. Often, this faucet has both hot and cold on at the same time.
These faucets have built in backflow preventers (sometimes a little ball
under the hot and cold stems). If these fail, then when you use the faucet
in a nearby sink, water will flow from the hot at the rinse sink, through
the faucet and into the cold pipes leading to the other sink.
As an experiment, close the rinse sink faucet at the hot and cold handles,
and see if the problem clears up. If the problem persists, there are other
suspects (like washing machines). Write back with more info.
I'm a plumber that works at an old school also. You may have an old faucet
such as and american standard,symon or water saver that has a round gasket
that seperate the hot and cold in one chamber. Turn on the cold water of the
offending valve and let it run. Then walk around and feel all other valves.
the warm ones are you culperits. rebuild them.
Hope It works for you