Use Shelly 1PM Gen4 to control hot water cylinder

I recently purchased a Shelly 1PM Gen4 switch to control my hot water cylinder. Sorry for posting in the Gen3 forum, but I couldn't find a dedicated forum for the Gen4 switch.

My plan is to have the switch turn on my hot water cylinder at 03:00 every day when our power is the cheapest. I realise this is trivial to achieve with the Schedules feature.

The second thing I'd like to achieve is once the cylinder has been turned on at the specified time, it must turn off as soon as the water has reached the set point temperature and the power consumption drops. This is to ensure that the hot water cylinder doesn't keep turning the heating element back on during the day as the water temperature slowly drops, since my power is rather expensive at other times and the small drop in temperature until 03:00 the next day does not bother me much. The turning off of power to the cylinder has to be based on drop in power usage and not time-based since the amount of time taken to heat the water to the set point temperature can vary based on the hot water usage in the previous day. How can I achieve this? Can this be achieved using the Actions feature, or would I have to write my own custom Shelly script? If I have to go the route of a custom script, could someone please point me in the right direction? I'm a first time Shelly user and am finding the documentation online a bit difficult to navigate. ChatGPT isn't of much help either.

Thanks a lot!

thgoebel - Thanks lot for your response. I actually did try something like this, but what I noticed it did was turn the cylinder off immediately (less than second) after it turns on at 03:00 since the instant it turns on, the power usage does not immediately jump up, but starts low and gradually builds up to 3kW over few minutes. Ideally, this rule should kick in only after the power usage has built up to around 3kW.

Oh that's a great idea! Don't know why I didn't think of that. Think that should solve my problem. Thanks a lot for your assistance!