I maintain an eighteen floor office high rise building and I've run into a new challenge I need help with. Hot water is in the toilets and sinks on the 14th floor. Now I have hot water in all the cold water outlets on the 18th floor. The floors have seperate water heaters,individual single handled sinks and flush valves. It shows up in the mornings until the cold water runs or flushed enough times, then the water is cool again. Has anyone seen this before. Help!