Pictured below is a controller we have just finished for a customer. We make a lot of rainwater toilet flush pump controllers, but this one is a little different from the norm.
This controller is for a pump with its own integrated run-dry float switch protection. A second float switch is located in the header tank. When the header tank float switch goes low (as the water level drops), a user programmable (1 to 99 minutes) timer starts a countdown. When the timer has elapsed, the pump is switched on with the on board relay, and is run until the float switch goes high on the increasing water level.
This version will work well for situations in which water is taken regularly from the header tank, and in particular in situations in which water will be taken from the header tank a few times typically during the timer countdown after the water level first used – e.g. multiple people coming home at the same time and all using the toilet.
The advantage of this system is that only one float switch is needed in the header tank (and there is no need to estimate the time taken to fill the tank by the pump etc).
The disadvantage of this system is that sometimes when the header tank is not being used, the water level will drop because of evaporative losses or leaks in the pipework etc. To mitigate against this, we set up the controller to run the pump for a minimum of 30 seconds each time it is turned on, and also to require one continuous second of changed float switch condition before any action is taken so that turbulence is ignored and to avoid multi-switching (which could rapidly damage the pump).
If you need a pump controller for your well, sump, rainwater toilet flushing, etc, then please email email@example.com with details of your exact requirements.