Sorry mate im on my ipad so cant knock something up, but ill try and describe it better....
Ill assume youve read my posts about my single vessel build thread as you mention it in your original post above.
In my 1V rig, the wort comes out of a ball valve and as you know, back up top and in through the lid, down some copper pipe and right down into the mash where it is dispersed throughout the mash.
Sometimes though, for reasons i havent conclusively worked out yet, the grain doesnt make its way back out of the grain where it can be picked up by the pump again. If this happens, youll dry fire your element. Bang.
if its a bag issue with my setup, then all is well.....just make sure the bag has a good napisan soak and rinse after each brew, but if its something else more random, then i dont want to be having to sit there watching the sightglass for loss of return just in case it happens again.
Ive spent a heap of time annoying Qldkev about my thoughts for the rig, and he does a return underneath i think and it got me thinking....
If i returned it underneath, id stop the risk of not having enough wort to actually recirculate, no more blowing elements.
Only problem for me with idea is that im not sure my little brown pump has enough balls to run two recirculation paths effectively.
So, ill experiment with just using a bottom returning line only, with the occasional stir, and see how i go. Depending on results, i might try and do both top and bottom returns simultaneously.
My mash basket sits on four SS bolts about 120mm (IIRC) above the bottom of the pot, so there heaps of space underneath for an extra return path.
Hope this helps....if stuck though, ill try and draw something up for you tomorrow. Im off to play a gig tonight and just about to leave so i probably wont be able to check in again until lunch tomorrow.
Cheers,
BN