Here we reckon that 18 kW is sufficient for a sink, 21 kW is acceptable for one shower/tub. If you wanna feed more than one faucet you'd opt for 24 or 27kW. Less than 18kw is just poor.
High tech is the model which is remote controlled to a desired faucet temperature( If demand is higher than available power, these models decrease the flow by a extra valve. So you don't mix hot and cold and there are no surprises.
