@larknz:

 

cjkbarnett:

 

I've installed a Shelly Pro 1PM in a stand alone din housing to control my hwc. Been working a treat for the last few weeks now. Turns the cylinder off and on according to our off peak rates. Our cylinder is 2.4kw.

 

And the device itself does not get too warm, well within its acceptable range:

 

Warmest i've seen it is just over 60 degrees.

 

 

The building code requires a minimum temperature of 60deg for a hot water cylinder to prevent legionella growth. The graph would indicate that you are not complying with this requirement and are creating a safety issue for your household.

 

You have misunderstood, that's the temperature of the device controlling the cylinder.