I just had a hot water heater installed. I have 3 bathrooms. In one bathroom, the hot and cold water is fine. In the second bathroom, cold water only. In the third bathroom, no hot or cold water. Is there sediment in the lines? What could be happening? Please help!

Sounds like when you replaced the heater you disturbed some mineral build up in the pipes and now it's clogging your taps. Try this, Shut the water off under the cabinet ands open up the faucet. Remove the cartridge and check and clean the inlet ports. While the valve's open place a pan over it and turn the hot water on to flush out the supply. You should have a full sream when you do this. If not let me know. Good luck, Tom