# BIAB recirculating wort overflow



## meathead (29/9/14)

As the title suggests I have a problem
I brew with a 40L urn, crab pot strainer and voile bag
I have set up a little brown pump to recirculate the wort from the tap up and through the lid mainly for temp control
I was all happy with myself yesterday when I turned it on and then couldn't understand why the wort was overflowing. My understanding is this is because I'm not forcing the wort through the grain bed which is being compacted

My question is would restricting the flow help or should I just abort the project?


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## amarks6 (29/9/14)

As I discovered recently, if you pump the mash too hard you will end up with a stuck mash (and I had flaked maize in the grist which didn't help!)

But I don't understand why your urn would overflow. How did you create more wort in your system?

I think the answer to the over-pumping problem is to restrict the flow OUT of the pump with a ball-valve.


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## n87 (29/9/14)

you could put a float switch in, which will cut the pump when the level gets too high.
as for the main problem, no idea, im a boring BIABer


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## meathead (29/9/14)

I'm getting the feeling boring is better


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## n87 (29/9/14)

with a regular efficiency of 85%, and can get 100L out in a day before dinner... have time for mowing and general house work... no reason to change it


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## meathead (29/9/14)

Dr Rummy said:


> As I discovered recently, if you pump the mash too hard you will end up with a stuck mash (and I had flaked maize in the grist which didn't help!)
> 
> But I don't understand why your urn would overflow. How did you create more wort in your system?
> 
> I think the answer to the over-pumping problem is to restrict the flow OUT of the pump with a gate-valve.


From my understanding the wort takes the path of least resistance, in other words it stays on top of the grain bed


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## Eagleburger (29/9/14)

The voile I used wouldn't drain quicker than the pump could pump it in either. Simple solution would be to install valve after pump. I dropped the bag and now use a pot with the bottom sliced up.


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## MHB (29/9/14)

[SIZE=medium]Hybridised systems are always going to throw up some interesting questions. If you are going to recirculate through the grain bed then you will need to crack your grain accordingly.[/SIZE]
[SIZE=medium]With classic BIAB the finer the grind the better, with a recirculating system you need to create a permeable bed much more like the type of grist used in a 3V or Braumeister type system.[/SIZE]

[SIZE=medium]Which throws up the question how suitable is a bag for recirculating? With a malt pipe the recirculating wort must go through the malt, with a bag how confidant can you be that the wort isn’t or in large part just travelling down the sides. Egelburger using a pot with holes in the bottom has found a simple enough answer; there are plenty of variations on the theme.[/SIZE]

[SIZE=medium]A bit of redesigning of your system might be in order; some flow control after the pump and a better malt pipewould both help.[/SIZE]
[SIZE=medium]Mark[/SIZE]


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## panzerd18 (29/9/14)

With the commonly used food grade pumps as there anyway to change the flow rate?


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## black_labb (29/9/14)

panzerd18 said:


> With the commonly used food grade pumps as there anyway to change the flow rate?


A ball valve after the pump can dial back the flow rate quite well. Ive used it on brown pumps until I got frustrated with them failing before getting a Kaixin.

I'm running my recirculating system with the 19L pot with the bottom sliced up with an angle grinder. As Mark mentioned you need to adjust your crush to form a proper grain bed. If I'm doing a big lot of malt I'll crush a bit coarser to ensure I don't get any compacting of the grain bed.


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## aaronpetersen (29/9/14)

I found that the mesh of my voile bag was too fine and kept clogging when recirculating, which may be part of your problem. I switched to one of the bags that many HB shops now stock and that works much better.


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## Sambrew (29/9/14)

I have a HERMS system brewing 50l batches, i have a false bottom in my mash tun and have never had an over flowing problem or stuck mash. I would think about the suitability of the bag for a recirculating system- but it sounds like you have a stuck mash. Also I would be looking to upsize your tun to accommodate any differences in flow rates in and out (ie; you must not have much dead space in the top) and restricting your flow rate at some point (before of after -no difference) in your line. It also sounds like you could benefit from some rice hulls in your grist.


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## jaypes (29/9/14)

You could try regulating the voltage/amperage to the pump to reduce the flow.

Unfortunately I have never tried it and it is possible that it may not work too well with magnetic impellors

Just my 2 grains worth of advice


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## meathead (29/9/14)

I'm using a silicone hose so will put a clamp on it
A change of bag and a courser crush could help too


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## mattlea266 (29/9/14)

I used to use the crab cooker basket also. 3 things I think will help you. 
Drill a heap more small holes in your crab basket. Bit of a pain in the ass but helps.
Get a proper grain bag from HBS. I found voile too fine for recirculating especcially after a few uses. 
Use a grain mill or get grains milled. Deffinately wont get away with the old coffee grinder technique with recirc.

I have since upsized to double batches still using the bag and recirc with kaixon but have incorporated a herms as well. 
Hybridised Bastardised brewery. Works for me.


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## verysupple (29/9/14)

Others seem to have covered the stuck mash bit, so I'll chime in on the pump.

AFAIK the little brown pumps are direct drive (not magnetic drive) so throttling is a bad idea. If you throttle the input you risk lowering the flow rate too much and losing prime and if you throttle the output it'll increase the head pressure and could be detrimental to the electric motor.


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## pk.sax (29/9/14)

Back in my pillow case days, did many brews with just poly voile and a pump. Pump a little slower and crush a little coarser. If your husk looks like it has cracked into two bits down the middle you are marginally ok, could for better with wet milling if you are up for it and can grasp that the point is to moisten the husks, not the grains. Will make a big difference.

Oh, and definitely don't bother recircing through cotton voile.


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## dent (29/9/14)

verysupple said:


> if you throttle the output it'll increase the head pressure and could be detrimental to the electric motor.


There's no problem with throttling back the output of those cheap brown pumps - if it were a proper pump running into a dead head might be an issue, but these are too weak to matter. The brushless motors also have some overload protection anyhow. I agree that throttling the input is a bad idea.


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## verysupple (30/9/14)

dent said:


> There's no problem with throttling back the output of those cheap brown pumps - if it were a proper pump running into a dead head might be an issue, but these are too weak to matter. The brushless motors also have some overload protection anyhow. I agree that throttling the input is a bad idea.


Good to know. It never occurred to me that they'd have brushless motors and wouldn't over heat if the impeller slowed due to resistance.


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## aamcle (30/9/14)

Ive put a bit of work into Recirculating BIAB and found the easiest way was to have an inner basket a bit lower than the rim of the outer pot. If the bag then goes over the outer pot there is a strip of voil that isn't pressed up against metal and this is an easy overflow for excess returned wort.


Atb. Aamcle


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## meathead (30/9/14)

Thanks for that
That's the same setup I have so a new bag could be in order


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