Stuck in a moment (Stuck Mash)

[gmcardle]

I've now attempted my third all-grain brew, this time an IPA. I purchased this Exceedingly Good IPA mash kit and mashed in with 12 Litres at 67 degrees C and left the mash rest for an hour in my 42 Litre DIY cooler box mash tun with copper pipe manifold. After the hour I then added 8 litres of water at 80 degrees C, mixed well and left for another 15mins.

After the 15min I then attempted to recirculate the wort by opening my mash tuns ball valve slowly (half way open). The wort drained fine initially and I recirculated a few times until the wort flow then slowed until it completely stopped (stuck mash?). Note this was not caused by opening the valve too fast or opening the valve fully.

I blew air back up into the tub to clear the blockage inside the mash tun. I then stirred the mash up and recirculated the wort a few times again but it slowed running and got stuck once again. I then had to dump the entire mash into a spare clean bucket, wash out the manifold, put it back together, connect it back to the mash tun, add back the mash and finally it worked (not sure why). Also, despite recirculating the wort a couple of times before taking the first runnings the wort itself was a bit on the cloudy side, should it be clear or is a bit cloudy ok?

So now I've managed to encounter a stuck mash 3 times in a row and I'm wondering if it's my manifold, my technique or if I'm missing another vital step....I've no idea? People on YouTube make this step look so easy but it's left me in a sweat to say the least....I feel like I'm battling a fire, I dread recirculating!

Here is a quick showing my DIY mash tun. The slits on the reverse side of the long copper pipes are very similar to this photo.

Would be very grateful for any advice.

 

[Revvy]

You have run water through it with no trouble, right? There's no impediment with plain water? If that's the case, then perhaps grain is getting into one of the slits and building up by the ball valve and blocking it?

 

[gmcardle]

You have run water through it with no trouble, right? There's no impediment with plain water? If that's the case, then perhaps grain is getting into one of the slits and building up by the ball valve and blocking it?

Yeah I've testing the mash tun and manifold a few times by running plain water and it works a treat. It's obviously getting blocked somewhere and I can't figure out where.

Is it recommended to stir the mash up just before recirculating?

 

[gmcardle]

I have a large hop bag that would fit over my manifold, should I try that as an option on my next mash? I saw this mentioned on another post.

 

[Revvy]

Do you have a pic of your notches?

We haven't even gotten to the point of looking at your recipes to see if you have a lot of sparge sticking proteins in them, but I doubt you'd have three beers like that in a row.... So I'm first thinking mechanical.

Here's a stab in the dark.... How "stable" is the manifold with that little "hose bridge" could, as you drain the slight "vacuum" of the flow be somehow compressing the grainbed down and with it, pushing the manifold against the bottom of the cooler and blocking the flow? I wonder if stuck something, maybe a wood or plastic shim under it right at the opposite end from the valve so it keeps it from compressing?

Maybe runs some water through and push down on the manifold and see if you somehow restrict the flow....if you do try the shim...

Weird idea number 2.... when hot, could the little hose bridge be constricting like some soda straws do?

 

[ArthurDigbySellers]

I don't know if this has anything to do with it or not, but your manifold is basically touching the back and side wall of the cooler. In How to Brew, John Palmer suggests to keep the manifold slightly spaced from the cooler walls (about the width of your tubing) to avoid the water from channeling down the sides of the walls.

http://howtobrew.com/book/appendices/appendix-d/building-the-manifold

Maybe this is what is causing the problem? This would also explain why water works fine by itself but slows to a crawl when you are actually mashing your grain.

My manifold looks almost exactly like yours except I have about a half inch space between it and the walls of the cooler on all sides.

 

[Gibberoni]

Is that high temp silicon hose connecting the pipes to the valve?

You may be crushing it, impeding flow. I had a similar setup on a similar tun before I moved to a round tun with all stainless connections. I had the same problem where the flimsy hose had too much pressure on it and it closed it up. I also managed to pop it off a few times when vigorously stirring the mash! ha.

 

[gmcardle]

Many thanks guys, based on the suggestions above I've managed firstly to reinforce the silicone bridge between the manifold and the valve connector. I did so by cutting a small strip of copper pipe and slipping it into the tube which seems to work well ().

I will also reduce the size of the manifold itself so that it's not touching the side walls or the back wall of the cooler in addition to raising the end of the manifold off the back wall to see if that helps.

 

[gmcardle]

Is that high temp silicon hose connecting the pipes to the valve?

You may be crushing it, impeding flow. I had a similar setup on a similar tun before I moved to a round tun with all stainless connections. I had the same problem where the flimsy hose had too much pressure on it and it closed it up. I also managed to pop it off a few times when vigorously stirring the mash! ha.

You could be exactly right, I've now reinforced that tube see video below, so many thanks for that!

 

[gmcardle]

Do you have a pic of your notches?

Here's a stab in the dark.... How "stable" is the manifold with that little "hose bridge" could, as you drain the slight "vacuum" of the flow be somehow compressing the grainbed down and with it, pushing the manifold against the bottom of the cooler and blocking the flow? I wonder if stuck something, maybe a wood or plastic shim under it right at the opposite end from the valve so it keeps it from compressing?

Weird idea number 2.... when hot, could the little hose bridge be constricting like some soda straws do?

Many thanks Revvy, I've now reinforced that connector (see video above) so hopefully that solves the issue as it can no longer be compressed by the mash or by compression from the manifold itself.

 

[gmcardle]

I don't know if this has anything to do with it or not, but your manifold is basically touching the back and side wall of the cooler. In How to Brew, John Palmer suggests to keep the manifold slightly spaced from the cooler walls (about the width of your tubing) to avoid the water from channeling down the sides of the walls.

Thanks ArthurDigbySellers, I remember reading this too and I didn't take it into consideration at the time. I am now going to take that point on board and move the manifold away from the sides and end. Cheers for that!

 

[ArthurDigbySellers]

Hopefully the tweaks you made will solve your problem. I've had a couple stuck mashes but they were both the result of using flaked oats/barley with no rice hulls. Really frustrating when that happens.

 

[Revvy]

Hopefully the tweaks you made will solve your problem. I've had a couple stuck mashes but they were both the result of using flaked oats/barley with no rice hulls. Really frustrating when that happens.

Yeah, at some point this weekend I plan to brew a rye red ale with both malted and flaked rye... I have a pound of rice hulls for it.

 

[gmcardle]

Many thanks for all the help on my stuck mash guys. After reinforcing the bridge silicone tube to my manifold I have now been able to complete two brews without any issues when sparging/recirculating....sorted!