The SL-X9-35 is the top of the Blue Sky instant range. There is no dial: a round black glass panel is set flush into the front, with a digital readout and three touch keys — up, down and power — so the temperature is stepped rather than swept, anywhere from 30 to 55°C.

It pairs that with the stainless steel 3500W element, the harder-wearing of the two the SL series uses. Water heats on the way through, so there is no tank and no reheating; the heater fires once flow reaches 1 litre a minute and cuts out thermally at 60°C.

The case is a soft-cornered gloss shell that mounts on the supplied plate with G1/2 connections, and it comes with the shower handset, hose, inlet filter and flow valve. Give it a 20A breaker, 2.5mm² cable and a meter rated 32A or better.