Just been to a friend's house across the street to look at a Triton instant shower (fitted by yours truly about 4 years ago). It's a 7.5kW model with dual-element and the common high/low power switch on the front. Reported that the water is now "barely luke warm" even on the highest setting.

I was expecting to open it up and find either one half of the element open circuit, or a faulty high/low switch, bad connection etc.

Electrically, everything checks out though. The pressure & temperature cutouts are fine, all connections sound, both elements showing 13-ish ohms cold resistance. When powered up, I had 235V across both sets of terminals, and the ammeter shows a steady 16 to 16.5 amps being drawn by each element.

So why isn't the darn thing heating the water? [Linked Image] The element housing feels barely warm when running, although it does get slightly warm around the top after shutting off. The flow rate is still as it was before, by the way.

There must be 7kW+ of heat being dissipated in there somewhere by the voltage/current readings. I'm not familiar with the internal construction of Triton assemblies, but the only thing I can think of is that somehow the elements inside have become detached from the fins or whatever other exchanger is used to transfer heat to the water passing through.

Ideas?