Reverse flow 2-tier 2-vessel system

I wanted to share my latest modification to my single-vessel BIAB system. I basically added a second vessel (mash/lauter) that is fed by my electric brew kettle with reverse circulation from the bottom (similar to the Braumeister but with two vessels). The system is controlled by an Arduino using a modified version of Mathos Braudino code. When the pump shuts off gravity allows the wort to back flow through the pump and into the brew kettle. This provides automated mash-in and mash-out with no addtional, pumps, valves or hardware.



The advantages:
No worries about the pump exposing the heating element from slow flow in the conventional circulated BIAB approach.

No need to lift the bag to sparge

Simple: 1 pump, 1 heating element, 1 temp probe

Fully automated mash-in and mash-out

And the best part: I've programmed the Arduino to provide a delayed start. So, I can fill the system with grain and water and set the system to start eain the middle of the night or when I'm at work. When I return it is ready to start the boil. This should cut my brewing time down to about the same as extract and allow me to brew on other than weekends.

Details:

The second vessel is a plastic bucket with a false bottom. The false bottom is made from the bottom of another bucket drilled with holes. I've added 3 legs made from stainless carriage bolts to keep the false bottom from jamming too far into the bucket.


I put the false bottom inside a BAIB bag and put the bag and false bottom in the bucket. The thought behind this is to use the false bottom to seal the sides of the bag against the bucket so that all of the flow has to go through the bag and the grains and not sneek between the bag and the wall of the bucket.

Here is the bucket with grains and the bag:



Here is the mash in with the bag zip tied shut:


Return flow is from copper pipe near the top of the bucket:

I've tried one brew so far and got 65% efficiency. I normally get 70% with the single vessel BAIB. But, I only single crushed the grains. I normally double crush for the BIAB. That will be my next experiment.

-Mike

Well I tried a second batch and double crushed the grains.
I also went for broke and had the system start the process while I was at work. Luckily I had it start about 1/2 hour before I came home, because the pressure build up was enough to lift the false bottom and the bag started to block the return tube. I came home to wort overflowing the plastic bucket. Most of it was dripping back into the boil kettle but I did have a mess on the floor.

So, I think next time I will use a stainless bolt to fasten the false bottom in place.

You ever make another go of it with the modified false bottom? Curious how you're liking this.

I did do another batch. This time with about 12lbs of grain. The stainless carraige bolt held the false bottom in place fine. I'm still perfecting the setup though. I added a copper elbow, pointing up inside the mash tun to make sure the bag did not clog the outlet. But, now I will use a copper Tee. (The bag builds up enough pressure to force the elbow partially out of the hole in the mash-tun bucket. Because the elbow necks down slightly near the bend, this causes a leak. The Tee should just get tighter in the bucket when the bag presses against it.

Using the automated mash-in and using 1 gallon of hotwater for sparge after mash-out, I'm still getting lower efficiency than I was with a straight BIAB. On the next batch I will pause the system once or twice during the mash to stir the grains. I'm pretty sure that I should then see the same efficiency as with the signel vessle BAIB then.

I like the fact that I don't have to lift a bag of hot grain and water. I also like the fact that the flow rate for recirulation is very good without having to worry about exposing the heating element.