Mash tun woes

[Stu H]

Okay so a few months ago I "upgraded" from doing dunk-sparge BIAB to using a "proper" mash tun and batch sparging. It has been less than successful to say the least. For one, my efficiency has plummetted, and not only that, it's really unpredictable, and occasionally I have diabolical stuck sparges. I opened up the gap on my mill to compensate, but I'm still ocassionally getting these awful stuck sparges. Last weekend I had to take the mash out of the vessel, and push it through my old voile bag. GARRR!!!

Another problem is my brew software seems to not be able to predict the volumes I'll collect from the sparges, though it was fine with BIAB... Probably doesn't help I'm using crappy old bits of dowel with notches marked in it for my volume measurements.

As far as I can tell, the only real advantage so far about traditional mashing over BIAB is being able to varlauf, meaning clear wort, and less trub in the kettle. However at this stage I'd probably prefer consistency over a trubby kettle.

I'm considering going back to BIAB until I can afford a decent s/s mash tun with a false bottom (probably from Chris Banks).

However I was wondering if you guys had any ideas with what is wrong with my process/equipment before I chuck the baby out of the bathwater, and go back to BIAB, or spend a fortune on stainless? Any help is appreciated!

Here's my mash tun:

[Matt Smith]

I'm not sure if I can be of much help, but I can say that when I used to batch sparge, I would get stuck sparges from time to time, but after I moved to fly sparging it's never happened again. I read (from memory here) that it has something to do with the water level always being an inch above the grain bed during a fly sparge, meaning the grain bed is kinda in suspension, whereas with batch sparging the water level drops below the grain and compacts it down in the process.

My only other thoughts would be your runoff speed, having a slow runoff always helps. Also check the top of your grain bed next time after your vorlof, sometimes when Ive recirculated alot I'm left with this thick, cake kinda layer of flower ontop of the grainbed and the sparge water struggles to pass through it.

[Tilt]

Stu - not sure what the problem is but sure you'll get it sorted with a few pointers.

My MT is a dead ringer for yours (without the flash tap!) and I consistently get 75% efficiency and have never had a stuck sparge so I'm sure you'll be able to sort whatever it is thats giving you troubles.  Having said that I mostly fly sparge and don't seem to have any problems with channelling or variable outcomes using the braid filter - with batch sparging that shouldn't be a problem anyway.

A few questions and thoughts come to mind...

Are you stirring your mash to dissolve all the sugars sitting in the tun before running off each sparge?

What rate are you running off at?  I keep my flow around a litre a minute for the first 2-3 litres to let the grain bed settle gently - then I can open it up to twice that rate and not get a stuck sparge.

Are you consistent with your pH and temps for your mash and sparge water?

Re efficiency - a bit of a long shot but I had to recalibrate my electronic thermometer a while ago - have you cross checked your measuring tools (thermometer and hydrometer) against somebody elses? - just to be sure these aren't giving you duff readings. 

Bro - don't diss the dowel - I use a bit of aluminium tubing with a chair leg stopper siliconed on the end and engraved marks as my dual purpose portable thermowell/measuring dipstick!

And another long shot - does your braid retain its shape when its got a load of grain on it (it looks a tad crushed at the top arm on the photo above - maybe the wort isn't running that well through it?)

[Stu H]

Cheers for the reply dudes!

No I don't stir before running off the first runnings, though I definitely stir after each batch sparge.

I'm running off with the tap on full, it doesn't seem to make much difference though, as half the time it's stuck!

I check my pH with strips, and it always seems to be about right, though the strips are difficult to read.

I use a glass thermometer and not really had any problems with it - it seems to be about the same as my thermistors that came with my thermostats.

Maybe the braid is getting a bit crushed, maybe it's worth taking it off and giving it a bit of a re-shape?

Still my biggest beef is getting the correct amount of runnings... The brew software (beertools pro) always seems to undershoot.

Maybe I should try fly sparging?

[Chris Banks]

Going to a shiney stainless mash tun would solve all your problems!! ;-)

But seriously what Matt and Tilt have suggested is all good advice - the runoff speed is the key I reckon

the rates Tilt suggested are approx what I used in my chillybin/hosebraid MLT to avoid stuck runoff.

 

Re efficiency - batch sparging how many sparges do you do? I was doing a couple , mixing it up well before recirculating each time and getting 79% every time.

I think the theory is that all your runoffs should be of equal volume also to help efficiency but this is not always practical.

 

[Tilt]

I'll have to eat my words about not having a stuck sparge after yesterday's brew. 

In an attempt to get crystal clear run off on a Golden Strong Ale (which was mashed low at 65) I vorlaufed too long using the 'run into a jug and transfer back to the tun' method.  Over this time the mash temp dropped to 58.  After 5 litres in to the kettle the grist set like  a block and stuck fast. 

Fixed the problem by heating a few litres of runnings to boiling (mash came back up to 70 degrees) and stirred/ vorlauf again, briefly this time.  What surprised me was how the grist actually set in blocks and chunks the size of my fist - I'm guessing due to the drop in temp.

So another option you could look into -  make sure your sparge additions are hot enough to prevent them dropping the temp of the mash too far.

[Dougal]

I've had the sparge stick after vorlaufing on my identical mashtun (especially without a temperature rise to mashout), and found that other than milling coarser and taking a drop in efficiency, the best thing is to not stir so vigorously. By dredging up all the fines into suspension you create a layer of flour that prevents free flow of the liquid. I now gently move the blade of my mash paddle back and forth to break up any dough balls, and do the same when I add the sparge water. I can now vorlauf to my heart's content, and the efficiency is up a few points even on big beers.

[Tilt]

Gordon Strong's book suggests cutting a light criss cross pattern in the top of the grain bed with the mash paddle or spatula to help prevent the fines layer from clogging things up.

[Dougal]

Interesting, I think that's what I'm inadvertently doing...

[Stu H]

interesting! I'll give that a shot!

[Richard Jack]

Also have a more or less identical mash tun. I had one awful, awful stuck sparge on an imperial stout with the tun full to the very brim, and have not had the same problem with similar loads since. What I've changed is a slower run off, especially at the start, being careful when stirring not to stretch the braid out (closes up the holes), and gravity feeding the sparge and mash in through the braid and up through the grain bed (which in my head might stop stuff getting squished into the holes as much? never heard of anyone else doing it though so maybe disregard that, haha).

[Tilt]

Feeding in from the bottom hey... might have to try that.  Do you get any less temp loss on strike or fewer doughballs with a closed system, more distributed mash in feed?

[Richard Jack]

No difference in temp loss that I've detected. I find that I'm getting less doughballs, but not much. Because I start stirring while the grain is only sorta damp from the bottom feed, it seems to break up the balls before they form. This might be hard for people without a thermostat keeping the HLT at the right temp, and a good gravity drop though?