I just replaced an old electric hot water heater, roughly 10+ years old, with a new one. This was done in the early am, before noon. It is now evening, after 6pm EST. and I've noticed two things. 1) My hot water pressure is now low in all of my faucets, but the cold water is fine. 2) The water is still not hot... not even luke warm. A small section of pipe, less than a yard had to be replaced. It was leaking and once it was removed, we discovered it clogged completely. Could there be a build up of sediment in the pipes (lead), that may have moved, causing the low pressure? Hot water pressure was fine, although not as strong as the cold, before pipe was replaced. Not sure why water temp is not hot either. Is there something that I can do to correct these issues?

Could there be a build up of sediment in the pipes (lead), that may have moved, causing the low pressure?
BINGO! I think you called it. The mineral build in the pipes broke off and is now throughout your system clogging the hot water inlet ports and seats of your faucets.

Is there something that I can do to correct these issues? Yes but it's going to be a hassle. All the faucets affected will have to be opened and the inlet ports checked and cleaned ,plus turing on the hot water to flush out the supplies and open valve bodybefore reassenbling the valve. If you have a 3/4" hot water main then that should be flushed as well. Sorry I couldn't be more up beat but I don't see any other options. Good luck, Tom