House was built in 1928, downstairs bath is fine but upstairs sink and shower get 0 hot water although radiators are working fine. New hotwater heater installed 3 years ago. Any advice on where to start looking would be greatly appreciated!

The radiators have nothing to do with the hot water to faucets.

Are you getting water to the hot water side or no water at all?

Have you checked the faucet strainer to see if it is clogged?

Chuck