Stuck mash, Biab bags and recirculating

[Tytonegro]

Hi,

I'm designing an electric one-pot RIMS system where I use a BiaB bag to hold the grain during the mash. You could say: another Braumeister clone...

I'm not a real metal worker and my wife is handy with the sewing machine ;-) Therefore I opted for this bag solution instead of some metal false bottom with slits/holes that act as a sieve. I see quite a few people making 'Braumesiter' clones, using malt pipes and the like. In my first attempts, I used a false bottom (with big holes) and had the bag sitting on top of that, just to prevent it from touching the bottom/heater.
I use a small 12 Volt pump (the brown Chinese one ;-) that is rated 109 G/hr (6.9 L/min) and I found that it runs dry because the wort doesn't flow quickly enough through the grain bed and filter bag. In my first version, the bag was sitting against the wall of the brew kettle so that in the end only the bottom was 'available' as active filter area. The version I tried today is shaped like a bucket, so it tapers to the bottom, and hangs free in the kettle, so that the total submerged area is available for passing the liquid. It has a perforated pizza bottom that prevents the bag from bulging at the bottom.
But alas, still not good enough. Within 30 sec. you see the level of the wort rising inside the bag with 2 or 3 cm (1 inch) and it doesn't take much longer or the pump runs dry.

Especially when the system is heating up in a multi-step mash, I would like the pump to run continuously to avoid overshoots in temperature.

I read that even the Braumeister suffers from this type of blocking with higher gravity beers. Therefore I was wondering what solutions people have come up with that work.
Just pumping slowly?
How much is slow or too fast?
What volume rate per area is more likely to work? (of course it also depends on the height of the grain bed.)
Any other solutions or ideas?

Thanks a million,

I've included a few pics to clarify

 

[mdwilson]

I had the same set up. Mine had an inner basket that I drilled larger holes in. I had to restrict the flow on the pump to about 75%, but still had problems with recirculation. Then I purchased a bag from High Gravity http://www.highgravitybrew.com/store/pc/Nylon-Bag-15-Gallon-Fine-Mesh-158p4090.htm. It is the same one they use in their BIAB system. The mesh is a little coarser and the flow was much better. I didn't have any problems after that.

I've since gone to a two vessel system https://www.homebrewtalk.com/f235/revised-2-vessel-system-488123/ where the wort flows from the bottom of the mash tun up (Braumeister clone in two vessels instead of one). With this system I can let the pump run full speed and the mash tracks temperature much quicker.

 

[jwalkermed]

i have a valve on the output of my chugger pump and throttle during the mash. I don't think you have to recirculate very fast to get the benefit of recirculating a mash. I probably have my valve 1/4 to 1/2 open I'd guess. Temp stays w/in 1 degree. I also stir every 15 minutes or so.

 

[virgil1]

I just had the same problem with my last brew. I am using BIAB, Chugger Pump, usually have it full blast(wide open). I have one of the northern brewer bags(https://www.northernbrewer.com/shop/brewmaster-filter-bag-214-214). Its a 14 gallon pot(Bayou Kettle from Amazon). It was recirculating fine for about 45 minutes, then I lifted the lid to check it out, and noticed the water was much higher. The wort from the pump to the top of the kettle was flowing pretty slowly(which is why it didn't build up fast and overflow). It wasn't coming down very fast. I lifted the basket out, with the bag in it, and had it hanging just above the kettle. I used a metal spoon(sanitized) to stir it and it eventually all came out. Did you find a solution?

 

[Tytonegro]

The solution I found was using a bag made from rather coarse mesh. 0.5mm it is said to be. At first I would not believe that a big amount of floury stuff would pass through, but it's absolutely working perfect now.
Btw: I start pumping 10 minutes after I have mashed in. The grain gets time to swell and settle.

Here you can see my set-up at work:

[ame]https://www.youtube.com/watch?v=Jgzw1Vcea4Q[/ame]

PS 2 a Grainfather mash tun has a sieve with even bigger holes, but only the bottom area is available for filtering. They rely on overflowing....

 

[schiersteinbrewing]

Check out this discussion and see if anything helps.

https://www.homebrewtalk.com/showthread.php?t=543873

 

[1MadScientist]

The solution I found was using a bag made from rather coarse mesh. 0.5mm it is said to be. At first I would not believe that a big amount of floury stuff would pass through, but it's absolutely working perfect now.
Btw: I start pumping 10 minutes after I have mashed in. The grain gets time to swell and settle.

Here you can see my set-up at work:

https://www.youtube.com/watch?v=Jgzw1Vcea4Q

Out of curiosity, what mill gap setting do you use?

Nice video. Do you bother stirring the grain any during the mash, or not?

The standard BIAB bag material is voile fabric. It worked good in the beginning without a pump, and today it's still the gold standard with a pump. I agree that a 6.9 L/min flow rate or lower works best. Over on the thread schiersteinbrewing linked, we are discussing mill gap settings among other things.

 

[Tytonegro]

Out of curiosity, what mill gap setting do you use?

Nice video. Do you bother stirring the grain any during the mash, or not?

The standard BIAB bag material is voile fabric. It worked good in the beginning without a pump, and today it's still the gold standard with a pump. I agree that a 6.9 L/min flow rate or lower works best. Over on the thread schiersteinbrewing linked, we are discussing mill gap settings among other things.

I have a cast iron "Corona" mill. The construction is so in-accurate that I always get a huge range of particle sizes, but I try tp go as small as possible, although I have to admit that I nowadays mill coarser then before.

 

[virgil1]

I did a brew this past week. Things went really well. Unfortunately I did more than one thing different, so not for sure if it was one thing or a combo.
1. Once I put my grain in, I let it sit for several minutes(and stirred). Don't think it was quite 10.
2. I have a new BIAB bag. Bought a Wilserbrewer bag. So much better than my Northern Brewer bag.
3. This grain was from Seven Bridges(organic grain). The batch that stuck was from more beer.
4. I ran the pump 'vertical' with inlet coming in the bottom, outlet through the top(see pic)
5. I used the hop bag from Wilser during my boil. I had the top of the bag hanging out of the pot and tied to the side. I used Muslin bags before that I just tossed in(pretty sure they were sucked to the bottom when the pump was on)

My PID seems to overshoot at first, and I usually shut everything down(pump and heat) while it cools a few mins. I noticed when I shut it off, some of the grain gets sucked out the top and into the pump. Twice when I started the pump, it wasn't working right. I just shut it off, waited a few seconds, and turned it back on. Seemed to push everything back out(into the top). I have some silcone tubing coming in from the top that is probably 8 inches long. Might shorten that or come up with a different solution.

When I was 'boiling', I set it to 210. I had it at 211 and 212, but I had the issue with the pump 'sucking air' as bubbles made it into the pump. 210 was the sweet spot for me. Every 10 seconds or so, it would boil up.

See attached movie.

View attachment beer.mov