Have no fears. I have been using a 'Redring' hand wash water heater for a few years now with no problem.
I can even adjust the temp to within a degree for washing B&W and E6 and C41 by marking the control arm against the case of the heater. Also, I have installed a filter in the system. Used in conjunction with my Jobo CPP2, it is a perfect combination.
You will not need to get the elecrical board in to install, as the system is designed to work off a 13amp domestic outlet socket. As far as a circuit breaker is concerned that too is no problem as you can buy a breaker that also serves as an outlet for the heater. Any other problems just shout....