Troubleshooting Mash Tun Issue

[edramshaw]

The ability to do this would likely depend on how the dip tube enters the screen, and whether the screen is the full inside diameter of the keg. What are doing with your recirc? Do you know your flow rates on your pumps?

The screen is the full size of the bottom of the keg and the dip tube enters straight down into the center of the screen. It is a 1/2 piece of copper tube that comes straight out and right angles into the center.

Is your fb domed? Ihave a 9" fb in my keggle and believe I leave more than a cup of liquid there, and there was alot more when I used my 12" cooler fb in the keggle. It may seem weird but if the screen is domed that it is sitting dome up.

It is not domed but I suspect that when the grain sits on it that it does bow in the center slightly. The nuts prevented it from hitting the bottom of the keg which I thought was the problem. I just happened to noticed when I removed my screen that the nuts where still sitting there and the liqquid in the bottom of the keg just reached the top of the nuts. I looked at this as a good indication of how much liquid qould be in there when the screen sat on top.

Post subject: Re: Troubleshooting Mash Tun Issue Reply with quote
I had the same problem with my false bottom years ago, since switching to a braid I have never had a stuck mash....

Do you have a post on here indicating the build on this style mash tun. Sound like it might work.

Thanks for the input guys!

[Quin]

Throttle down the output of the pump.

+1. You need to run the re-circulation pretty slow at first

[edramshaw]

So I did some modifications are brewed yesterday and heres what I got. I found that the 1 cup of liquid I saw was as a result of the screen falling onto the top of 3/4" nut I had at the bottom so there was room for more if I could hold the screen up further. I addred 2" bolts with do nuts as was suggested to provide support. Recirc started off ok but stopped about 10 minutes in. I had it throttled back halfway, probabllly flowing at about a gallon a minute. I have to say the wrestling around to get the flow back was easier than the last batch (although that could be because I was only dealing with 23.5 lbs of grain vs. 40 lbs. last time). I would get it running, try to choke it back and it would continue to stop on me. It wasn't till the end when I had it choked way back that I got it to run steady for 20 mins or so until i completed the recirc. It looks like progress was made with the raised FB but it still not where I want it. I also added rice hulls to the batch to see if that helped as well

Question: The flow was really slow, I am pushing it through a 1/2 copper hard piped manifold. Is that, perhaps, too big of an ID which would demand to high of a flow rate to avoid sticking the mash. WOuld I benefit from reducing the ID of the piping? What size are you guys using on the output of the pump with regards to tubing ID(either hardpiped or flewible)?

[PSUHomebrewer]

I use 1/2 copper for my recirc arm also without problem. I did go to modify it one day and found it was particaly cloged with grains and husk, rebuilding it with a clean out on each end. I usualy run my recirc with the valve on the tun at 1/2 open and same on the pump without problems with good flow through the arm. Its going to take some time to get the flow just right, it took me about 3 batches to figure out the optimal rates.

[Kbar]

Question: The flow was really slow, I am pushing it through a 1/2 copper hard piped manifold. Is that, perhaps, too big of an ID which would demand to high of a flow rate to avoid sticking the mash. WOuld I benefit from reducing the ID of the piping? What size are you guys using on the output of the pump with regards to tubing ID(either hardpiped or flewible)?

Reducing plumbing size to limit flow is not the correct step. With non positive displacement pumps, one can go with large bore plumbing, but simply use the ball valve (better yet, needle valve) to control output flow.

I would rather use 1" or 1.5" (read: tri-clamp) plumbing and rely on the valve for flow limitation. Due to suction characteristics, I would much have larger plumbing on the suction side.

Keep flow slow in the beginning to allow the grains to swell and reduce compaction. The question is, why are the grains getting by your false botom and clogging the pump inlet...........

[raven19]

Is there another experienced brewer nearby who is able to come around during your brewing to observe and add further suggestions?

Reads like a super annoying problem now!

[Cliff]

and use two chugger pumps to move liquid around.

I'm thinking maybe you are pulling too hard? That'll stick a mash

How about building a lauter grant? A little pot of some kind into which your mash flows VIA gravity and from there you pump it using a float switch to turn the pump on and off.

[gwk453]

If you go back to AJ's rice hull solution start there and make sure your not crushing the snot out of you grain! It sounds like the design (limited space under your false bottom) is contributing so keep your recirculation flow slow.