Originally Posted by bknifefight
TO create a suction when draining, attach a hose to the valve on your mash tun. Doing this and keeping the valve only half open should maximize the wort you get from your mash and not create any channeling.
That'll work provided that the braid doesn't go all the way up to the cooler outlet. The siphon will break and drainage stop when the liquid level gets down to the first point that allows air to enter the flow path. If there is an airtight connection from the cooler outlet point down to near the floor of the cooler, either metal or tubing, then the siphon will continue until the liquid drops down to the top of the braid - on the other hand, if the braid goes right up to the cooler outlet/ball valve inlet, then the siphon stops at that level.