My water heater is hard-plumbed with galvanized pipe. It is at least 20 years old and is leaking:
I want to use modern flexible hose for the new water heater, but I don't know the best way to change the existing setup. I could simply take off the unions and try to thread adapters to the pipe stubs, but I'm concerned that the existing threads will have corroded to the point where it won't make a good connection.
How should I proceed?