I'm building a biab system very similar to the one here: https://www.homebrewtalk.com/showthread.php?t=596834&highlight=Recirculating+biab
Quick shoutout to trav77 for his inspiring build and Doug293cz for making these diagrams for everyone. This site is incredible and the members here are...
I'm building a similar controller, but it includes a keyed switch and 2 contactors. Are the contactors unnecessary? Would it be possible to add a keyed switch to the diagram you provided Doug293cz?