Stuck mash on first AG brew

[bicyclerepairman]

Hi all,

I've finally acquired all the bits and bobs to do a 5gal AG brew, and today was the first test-run. I only did a 1 gallon batch, so I wouldn't waste too much in the learning process....

Here's the set-up:

Among other problems, I had a stuck mash. I've previously used a double bucket arrangement with loads of holes drilled in the inner one, but this one uses a copper pipe manifold in a picnic cooler

Before I go up to a full size batch, I want to be sure I don't get a stuck mash again, cos I had to resort to desperate measures and it was a right pain in the backside.

I put in 4l water, followed by 2.5Kg grain. Later on, I added a further 3l water.

The flow was initially great, but very quickly slowed to a dribble.

I figure there's several things I could have done wrong:

1. Adding the water and grain in the wrong order, clogging up the slits straight away

2. The grain was the dregs from the bottom of a very old sack, which I'm guessing had plenty of time to settle because there was a lot of small particles of malt and dust.

3. I initially had the slits facing down

4. The slits are too small

I'd really appreciate any advice from more experienced brewers!

Thanks!

 

[Cononthebarber]

Did you use a tube on the outlet of your mashtun? If not this may have been your problem as there would be little syphon effect to pull the wort through?

 

[Dave1970]

I use a similar brass manifold with slits, not had a stuck mash yet :pray:

I'm guessing from your photo that your slits are about 15mm between slits (assuming that's 15mm pipe you have there), I have about 2-3mm between slits so I'd be looking to fit another 6 or so slits inbetween each of yours. I'm pretty sure this is the main cause of your problem.
As far as facing up or down, I always have mine facing down because it reduces the dead space but I guess this might reduce the risk of stuck mashes too because the weight of the grains isn't pushing directly down on the slits.
The width of your slits looks about right.

 

[joe1002]

As Daves says, a lot more slits and have them facing down :thumb:

 

[bicyclerepairman]

Thanks for the replies! Glad to know I was on the right track.

I'll cut a load more slits in - I originally had them facing down to reduce deadspace, but put them up for the photo.

Also, I'll ad a syphon tube - good idea, didn't think about that.

 

[Dave1970]

I don't know how much difference the tube makes, I have a length of tube on mine but when I'm sparging the flow rate isn't anywhere near high enough for there to be a continuous column of fluid in the tube so there won't be any suction effect.