I'm a plumber with an electrical question... I'm replacing an old Rheem water heater (like 40 years old) with a new Lochinvar heater. The old heater has electric run to it through a piece of what looks like romex cable (I attached a pic) run straight out of a solid concrete wall. The new heater requires 240v and the old one was a 230v. My question is basically what are my options and what should I know... I don't want to run into any problems and leave people without hot water. I also attached a pic of the old heater label...

The service is supplying 240 volts now, and the 230 volt heater worked fine with it.

Beyond suggesting the new heater gets connected according to the manufacturers instructions I don't know how else to help, unless you have some specific questions.

Electricians don't do plumbing unless their licensed and/or qualified, shouldn't that be the same vice versa?