I was hoping to set up a type of ‘One Shot’ variable timer for water heating based on the current ‘heat/energy’ of the water storage tank. The water tank has 4 temperature sensors (top to bottom) and using a formula which access the total energy & current temperature at the top of the tank I wish the timer to come on for an amount of time to bring the energy/temperature to a predetermined value. In other words if the tank is hot enough then timer will be zero, if it is cold then heating time could be 40 mins, or any value between these. This would be triggered either by a button (for hot water now) or a timer (for hot water in the morning). Is this possible with PLEG or PLTS.
You could do this in PLEG by using a SelfTrigger timer (Schedule). The Action to start the timer can include an optional intervalTime. This is in seconds so you would need to multiply your minutes by 60.
See PLEG Basics for more details.