According to Dave :
I understand what everyone else were saying on here, and I am not an
electrical expert..but.. wouldn't it depend on how the wire is connected at
the electrical panel. What would happend if your red is connected to the
'hot' point and the red is wired to the neutral (white)?
Can someone else add to this?

A water heater requires 240V. When correctly wired, the black and red
wires supply the 240V. "Correctly wired" means that the black is connected
to one side of the hot feed in the panel, and the red is connected to the
other side. There's 240V between them, and 120V from either one to neutral
(usually white).

It simply doesn't matter "which way around" they are.

There is _no_ neutral needed in a 240V water heater. Just two hots
and a protective ground (usually bare).

If, on the other hand, the electrician wired one of the wires of the
HWT (red or black) to the neutral (coloured white in cables, one
of the busbars in a panel), the HWT is only getting 120V, not 240V.
The HWT will work, but it will take a very long time to heat up.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.