Temps where around 8C lower under load WeaselBlade.
The project has been mothballed for the time being due to unforseen circumstances:
Sold my business along with a lot of the tools and machinary, and have been very buzzy with a computer business.
I will finish it at some point.
However the cistern rusted up as I feared.
This will have to be replaced with a: float, micro-switch, relay, pump setup.
Will post some more pics and screenshots if anyone is still interested?