is it possible to use the float switch with a asco type valve to control wort flow? I would like to use it with my hop back, the level of my hop back is below my boil pot so the wort bleeds back from the pump and turning off the pump will not work.
it is definitely possible, you would have to run the float valve through a 12v Relay coil and run the asco line through the contact point, basically the exact same set up as for the pump control, except you plug the asco in, assuming its 110v.
I'm doing something like for my wort heater/chiller. Using one coil and a 3way asco, the pump will pump the wort through the grain bed constantly, and depending on the temp of the wort (set on a RANCO ETC) it will either direct the wort through the heat coil or a bypass back into the mash tun. Then, after final boil, i fill the HLT with cold water/ice and run the hot wort through the coil, set the temp to my pitching temperature and recycle the wort through until it cools, then just pump out to fermentation. It basically creates a hybrid counterflow, cold water passes through the HLT and out the drain while the hot wort is run through the coil. once the temp is down a bit (140deg or so) i throw in ice and it chills very quickly. In the winter with cold house water the ice isn't really necessary, just faster. I suppose you could go a step further and get some glycol or AC unit to chill it, but this seems to work.
In any case, yes, you can hook the valve up to the float, not a bad. I may do that for sparge and drain to fermenation.