Weizenbock Failure

[Fritzpoll85]

Now I've had a cup of tea and a think, I thought I'd write thing one up in case anyone can learn from my mistakes.

I had some success recently getting better efficiency on my weissbier by two things a) better pH control and b) changing the grain crush. So I began to make a banoffee weizenbock - my biggest beer to date with an SG of 1.070. Needed over 7kg of grain in my Grainfather G30, and around 50% of the bill was wheat. To counter that, I added around 300g of soaked oat husks. But everything was fairly finely crushed

I set up for three mash steps - 25mins at 45C, 60mins at 65C and 10mins at 75C.

The problems began early on. I often have to reduce the pump speed using the red lever because I don't like relying the overflow, but I was having to constantly adjust it down to let the liquid drain through. About 15 mins into the second mash step, I stopped and stirred the mash, but this didn't really help

The real issue was the sparge. Liquid was coming through, but a bare trickle. After half an hour, I'd managed to add 1 litre of the 10 litres of sparge water. I therefore lifted the top plate, and tried to stir it, as well as adding extra oat husks.

But the issue was that the liquid only ever passed through if I got the stirring paddle to literally scrape the grain off the bottom plate. But as soon as I the grain settled back to the plate, the sparge stuck again. After a a good hour of trying to be patient, I ended up having to constantly stir the grain to rekease the water

The first noticeable issue with this was very low efficiency, as measured by pre-boil SG. I could also see a lot of flour and crud in the wort. I decided to try to crack on, but mixed in some extra sugar to compensate.

When I tried tasting the wort, there was a slight aftertaste like slightly overstewed tea - this is probably tannins extracted from the grain because of the sparge issues. But again, I decided to carry on and see how it turned out.

Unfortunately the grainfather had a different idea. 15 mins into the boil, the heating element tripped. At this point, I decided I couldn't recover since it seemed obvious that it was all the suspended matter burning onto the element.

So, with regret, I dumped the lot. Here is the bottom of the GF, showing the burn.



Now, I'm going to recover from this by brewing a simpler dunkelweiss mid-week. I need to wait for MM to reopen before I can get the ingredients (and source some alternative Weyermann Chocolate Wheat malt)

But lessons here are:

* Watch the grain crush - mine was clearly too fine and I'd ended up with a fine crush on the barley malts as well
* I don't think any amount of oat husks would have recovered from the over fine crush.
* I'm going to scale the recipe down - this was a 22L batch, but if I make it 19L then the total bill goes down to around 6kg instead of 7kg. I think this will make manipulating the grain a bit easier for the bigger OG beers.

If anyone has any other tips to offer, feel free to add them. I'm going to try and cheer up with my homebrew cali common and helles weissbier.

 

[phillc]

I don't have a lot to add regarding your Weizenbock specifically, but I wanted to add that a very similar thing happened to me yesterday!

I was mashing 6.25kg of Maris Otter in my Klarstein Brauheld. Initial mash water was 15 litres. Re-circulation failed at any flow rate, due to the grain bed stopping water from flowing through. I added another 3 litres of water, but nothing changed. At the end of the mash, there was zero flow out of the mash. I had to stir the bed up, lifting the grain off the bottom of the basket, to drain the mash water. This then meant the sparge water flowed through way too fast and my efficiency was extremely low.

In 31 litres of post-mash water I had an adjusted OG of 1019, which I calculated would only be 1030 after boil volume reductions. I added 800 grams of dextrose and after a 3-hour boil (which was actually always the plan), ended up with 1082 in 23 litres. Still, I would rather have not had to add the sugar.

I didn't have any boil problems, managed to complete everything and the brew is now happily fermenting away. Taste might be another story......

Talking to a couple of homebrewing friends, one said he always mashes with much more water for big grain bills, starting with 25 litres in the mash and only sparging with 7 or 8 litres. The other, who has a Grainfather G30, said he never goes above 5 kg of base malt, due to just the same stuck mash problems you had!

Not a lot of help, and all I'm really adding is to reduce the grain bill, which you already suggested, or mash with a lot more water.

 

[Fritzpoll85]

Presumably there's a limit to how much extra water we can add to the mash before it starts to really affect efficiency? But only because we won't have enough sparge water

I think grain bill size was too high for me this time, and the crush was definitely poor

Sorry yours also didn't pan out quite to plan, but at least it wasn't just me.

 

[phillc]

Presumably there's a limit to how much extra water we can add to the mash before it starts to really affect efficiency? But only because we won't have enough sparge water

I guess so. The guy I was talking to says he always mashes with 25 litres and sparges with 8 - 9 litres, but seems to have decent efficiency.

My original plan called for 34 litres in total. 15 litres mash water and 19 for the sparge.

I'm going to try this brew again (as I have enough grain on hand, which needs using) but try with 24 litres of mash water and 10 for sparging. Even if efficiency is only 65-70%, it's going to be better than what I achieved yesterday! I'll keep some dextrose to hand just in case.

 

[The-Engineer-That-Brews]

That must have been absolutely gutting having to ditch the whole batch @Fritzpoll85 - sympathy for that, especially with 7kg of grain

After half an hour, I'd managed to add 1 litre of the 10 litres of sparge water

OMG... nightmare

I think you're right, it must have been the crush.

Just FWIW (and apologies to those who already know my views on this) I think that controlling the flow rate through pump is better done with a bypass tap: reducing the flow by restricting the output is a bit like driving at full revs with the handbrake half on. However I'm not familiar enough with the GF to know whether this is a viable option :-)

 

[Fritzpoll85]

I'm going to try this brew again (as I have enough grain on hand, which needs using) but try with 24 litres of mash water and 10 for sparging. Even if efficiency is only 65-70%, it's going to be better than what I achieved yesterday! I'll keep some dextrose to hand just in case.

Let us know how it goes!

 

[Fritzpoll85]

That must have been absolutely gutting having to ditch the whole batch @Fritzpoll85 - sympathy for that, especially with 7kg of grain



OMG... nightmare

I think you're right, it must have been the crush.

Just FWIW (and apologies to those who already know my views on this) I think that controlling the flow rate through pump is better done with a bypass tap: reducing the flow by restricting the output is a bit like driving at full revs with the handbrake half on. However I'm not familiar enough with the GF to know whether this is a viable option :-)

Yeah, but it was the first proper failure I've had getting a beer made (the other failure was after packaging) so I suppose it's a valuable lesson. About 13 quid of grain, so not the end of the world

What is a bypass tap (don't say a tap that bypasses!) - I'm not sure where such a thing could be fitted. I do agree that it is like using the brakes on a car with your other foot planted on the accelerator

 

[The-Engineer-That-Brews]

What is a bypass tap (don't say a tap that bypasses!) - I'm not sure where such a thing could be fitted. I do agree that it is like using the brakes on a car with your other foot planted on the accelerator

Heh - sorry didn't mean to be cryptic: just a tap fitted 'across' the pump with a couple of 'tee' pieces like this:

When the tap is fully closed you get the full flow rate of the pump through the mash tun; but the more you open it, the more of the flow goes around the bypass circuit instead. It allows the pump to continue running at normal speed, which will extend its life and reduce overheating. I think the higher flow rate (through the pump) also reduces the risk of it jamming because there's more energy for the impeller to whack through bits of crud.

:hat:

 

[phillc]

While a good idea for preserving pump life, I'm not sure bypass tap solves the problem at hand. The issue is that when the re-circulation water hits the top of the mash, it's taking a very long time to drain through to the bottom of the tun.

Therefore, when pumping out of the bottom of the tun, unless the flow is somehow controlled, the available water is exhausted very quickly. As the pump is not variable speed the only easy ways to slow the re-circulation is to either reduce the flow from the shower at the top, or constantly turn the pump on and off.

With my Klarstein Brauheld, there is an anti-burn jet at the bottom of the tun. This is also run from the same pump as the re-circulation, and kind of acts like a bypass, but back into the bottom of the tun. What one can do is run the pump, with the anti-burn jet tap fully open, but limit the flow through the top re-circulation arm. This way, the pump still gets full inflow, but limits the outflow in one direction.

Edit: Actually, looking at your second drawing, which I didn't see the first time, I can now see how this helps in general for the pump. My head was not around the flow direction before.

 

[The-Engineer-That-Brews]

While a good idea for preserving pump life, I'm not sure bypass tap solves the problem at hand. The issue is that when the re-circulation water hits the top of the mash, it's taking a very long time to drain through to the bottom of the tun.

Correct

 

[Fritzpoll85]

That's very interesting. If I ever build my own kit,this is the kind of thing I would be interested in exploring*, but I don't think I could retrofit this easily onto the GF

* mind you right now, I'd settle for a homebrew mash filter and then I can just brew with flour!