Are galvanised steel pipes suitable for supplying hot water?
If you have the opportunity to replace your galvanized pipes, do so.  It's an inconvenient project, involving opening up a lot of walls, but as you can tell from the comments, galvanized pipe is problematic at best over the long term.

It will frequently develop (as is the case in my own home and in my rentals) pin hole leaks.  The only good news with galvanized on that front is - the gumming will often re-seal those pinhole leaks, but not all the time, as my basement ceiling could have attested, before I gutted the whole thing.