I use one of these heaters - marketed as a wash-room hand washer. Runs at 3kW so can be plugged in to the normal house ring main (in the UK at least). With the incoming water at 5deg C, outgoing water on mine can be at 40degC (the temperature is set by adjusting the water flow rate with the knob on the front). Higher wattage version are available but will need a separate electrical circuit. More complex versions are also available - this simple one was a fraction of the cost of a professional water controller.Originally Posted by photomc
As with any electrical equipment used near water, make sure you use an earth leakage (a.k.a. residual current) circuit breaker - or whatever they are called in your part of the world - 'Powerbreaker' is one trade name I know of.
Pic attached (really must move that inspection light...).