As everyone knows, the rating of energy providers is increasing and one of the most greedy post is the water-heater.
Knowing that even with a Peak-times/Off-peak-times relay the heat time is excessive, I decided to manage the subject by domotizing.
For that I use a Fibaro FGS-222 (I know, one of the relays is useless but you never know) that I intercalate between the Peak-times/Off-peak-times relay and its circuit breaker.
I added a manual switch to be able to rollback to normal if ever my Fibaro was to break down or if my guests abused on the showers.
The Fibaro relay is managed by 2 rules in my Zipabox that turn it on and off as I please.
I went from 8 hours of daily heater to 5 and that is enough. It is not impossible that I reduce it again.
If it helps, enjoy