[BrewBama]

On the Dennybrew site, Denny says (paraphrasing) crack the drain valve to set the bed then open it as wide as the ‘comfort point’ of your system allows.  Runoff speed is described as a feature of batch sparging.

In Chap 18 of How to Brew, John says run off at a quart per min. I believe he is fly sparging.

He describes a balance between crush and runoff speed to get a factor of 29 to 30 when multiplying gravity points by pounds of grain used then divide by volume in the BK.

Both drain by gravity in these descriptions I believe.

Dr. Narziss of Weihenstephan suggest the equivalent of 0.18 gal/min ft squared as an initial lautering rate. To get this number, multiply this value by the area of the lauter tun.

SS Brewtech recommends .67 gal per min using their InfuSSion MLT.

I batch sparge but use a pump. I believe I have a good crush balance between flour and grits with intact husk. So, I am considering slowing my lauter speed in an effort to gain a point or three in John’s factor forumula but I want to balance that with not wasting time.  .25 gal per min is kinda slow. Maybe too slow?

I am also considering a rotameter to add in my flow path so I can monitor flow in gpm.

How fast (slow) do you lauter?  How do you measure your lauter speed?

[Slowbrew]

I have no science to offer on this but my experience has always been that I start my batch runoff with the 1/2" quarter turn valve about 1/4 open.  At some point the dribble in the tube starts to look like it wants to fill the line (I don't have a good way to describe it) and at that point I start opening up the valve to 1/2 or a bit more.

I tend to get a quart in 2 minutes or less so .25 gallons/hour would be way too slow for my patience levels.  Both runoffs take 25-30 minutes total including adding the water and stirring.

Paul

[denny]

If you truly batch sparge, runoff speed is not a factor.  Slowing will not make any difference in my expjerience.   At that point you would be closer to fly sparging than batch. AFAIK, John has never batch sparged.

As an example I collect 7-7.5 gal. of wort in less than 15 minutes.  That's draining the mash tun, stirring in sparge water, and draining again.  I average 84% efficiency.

[Saccharomyces]

I have always employed continuous sparging and a quart per minute is about right.  When I brewed 3-gallon (kegged volume) batches, I would runoff 4.25 gallons to yield 3.5 gallons at the end of the boil.  It usually took around 18 minutes to lauter that volume.  I never timed 5-gallon (kegged volume) batches but will once my new brew house is up and running.  However, running off 7-gallons was never more than a half hour affair.  That being said, I seriously doubt that runoff speed matters with batch sparging because that technique is based on stirring the mash until the dissolved sugars equalize in the hot liquor.  Continuous sparging is a completely different animal.

[RC]

I seriously doubt that runoff speed matters with batch sparging because that technique is based on stirring the mash until the dissolved sugars equalize in the hot liquor.

Exactly. With batch sparging, once equilibrium has been reached between the sugars trapped in the saturated grains and the surrounding liquid, all the liquid in the MT is at the same gravity, and so slowing the runoff in an attempt to get better lautering efficiency is moot. Channeling is not a concern either. It's still possible to get a stuck runoff with batch sparging if you runoff too fast and compact the grainbed, and so speed still matters to an extent, but slowing the runoff with batch sparging won't gain you any efficiency.

[Ellismr]

I fly Sarge and it usually takes me 80-90 minutes to bring over 14.5 gallons of wort.  It’s not a complete waste of time I use that time to get my fermenter sanitize and get my hops ready I make notes in beersmith such as, mash pH was and how things went in terms of milling grain and anything that may not have went to plan.  On average not having any major catastrophes my brew day is start to finish everything cleaned and re-stowed about 5 1/2 hours.


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[ravenwater]

If you truly batch sparge, runoff speed is not a factor.  Slowing will not make any difference in my expjerience.   At that point you would be closer to fly sparging than batch. AFAIK, John has never batch sparged.

As an example I collect 7-7.5 gal. of wort in less than 15 minutes.  That's draining the mash tun, stirring in sparge water, and draining again.  I average 84% efficiency.

My method and results sound similar to Denny's -  I mash in an orange cooler and batch sparge by opening the valve partially for a slow runoff into a cup to settle the grain bed and ensure I'm running clear, grain-free wort, then once I see clear wort running I open the valve completely and drain quickly to the kettle, add my sparge water, stir, allow the grains a minute or two to settle and repeat. I average 86%-87% extraction efficiency, which I'm happy with. I switched to batch sparge to save time, lost no efficiency and will never look back.

[BrewBama]

BLUF: Slowing my flow rate during the mash and runoff seemed to do what I was looking for. With all else being equal, I saw a slightly better extract efficiency.

I installed a rotameter in my flow path and received some interesting feedback from it. Here’s the results of my effort: 

With water alone the rotameter registered well over 1 gal per minute flow at my normal flow valve gap setting developed from trial and error. So, I lowered the flow and took a new measurement of the gap between the cap and body of the pump linear flow valve.

On my most resent brewday using the lowered setting it was so low it was nearly not flowing at all. That makes sense to me given the grain load restriction in the MLT vs water. This I believe is my initial differential pressure. Starting slow is a good thing.

So, I increased the flow and took a new measurement. But a few minutes later, it again had fallen below my intended flow rate. Again, I believe this makes sense as the grain bed begins to compress and differential pressure increases. So, I again increased the flow.

After a few iterations of this set, fall, set, fall, the bed must have found a differential pressure/grain bed compression equilibrium ‘sweet spot’. It did not fall again throughout the rest of the mash. The final gap measurement was more narrow than my original trial and error derived measurement prior to the rotameter install but wider than the test run with water alone.

However, keeping the same ‘sweet spot’ flow rate, once I redirected the flow into the BK, I noticed the flow reducing as the wort level in the BK increased/MLT decreased. I believe this also makes sense given the smaller and smaller qty of wort to grain ratio increasing the load and affecting the differential pressure further compressing the grain bed.

Slowing my flow rate during the mash and runoff seemed to do what I was looking for. With pH at 5.4 and all else being equal, I saw a slightly better extract efficiency. ...but I am intrigued with what to do about the runoff flow slowing at the same mash recirculation flow valve gap setting as the MLT drains.

I may increase mash temp prior to runoff in an attempt to lower viscosity. I usually do not increase to mash out temp.

Wort velocity, flow resistance, load, differential pressure, viscosity ...what a concept.

Ref: http://brewlikeapro.net/lautering.html

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[majorvices]

I wouldn't use a pump without a grant because you will be pulling on the grain bed filter as opposed to letting it lauter naturally, which could result in problematic lauters and excessive grain bits and possibly lipids. Your speed will depend  on what works best for your system.

[BrewBama]

I wouldn't use a pump without a grant because you will be pulling on the grain bed filter as opposed to letting it lauter naturally, which could result in problematic lauters and excessive grain bits and possibly lipids. Your speed will depend  on what works best for your system.

+1. I am understanding that more and more as I learn what is happening. I thought the area below the false bottom would act as a grant (the wort would drain into this area and the pump would pull from there) ...but I am not so sure now.

During the mash recirculation the wort flow in the sight glass becomes crystal clear as the mash time progresses. But as the wort is pumped from the MLT into the BK it becomes more and more opaque (but still see thru). I never concerned myself with this before as I see many folks with much cloudier wort in the BK than I have. Not near as see thru.

As the wort is pumped from the MLT I can now see the flow slows without adjusting the flow valve. The pump is pulling harder on the entire load not just the area below the false bottom. Of course this was happened before installing the rotameter, I just never knew it.

I am now able to see a link between this transition from crystal clear to opaque wort and the pump creating a vacuum (differential pressure) on the grain bed load slowing the flow.

Lautering would seem to be as simple as diverting from mash recirculation to transfer to the BK by opening a valve but I find it much more complex.

A grant design: http://www.fullstackbrewing.com/2016/12/06/How-to-make-a-grant/

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[majorvices]

No the space below your FB doesn't act like a grant. If you pull too fast it will go dry causing problems since the mash should always be floating on the liquid in the FB. You can devise two clear line of site glass tubing - one above the FB and one below - and these would stay close to equal while you run off. If the one below the FB drops too far below the one above the FB you are pulling too fast.

[RC]

These are commerical-level considerations. Seems unnecessarily complicated for homebrewing. It's like using a backhoe when all you need is a trowel, or even just a spoon. Just curious, what's the goal here? Is this a solution looking for a problem? If it's just playing around, totally cool, to each their own. Again, just curious. Cheers.

[BrewBama]

Mostly just playing around in an attempt to improve extract from the mash. Just an effort in constant improvement, process refinement, etc.  With all else being equal, early returns indicate slowing the flow to a controlled, measurable constant gpm worked for me. (I’ve only used this method once so more experience in needed).

I believe the faster flow I was using caused the wort to seek a path of least resistance around the grain bed or channeling through it reducing the extract points I was getting.

The rest was just a report on feedback I received from installing a rotameter in the flow path which I was trying to better understand and thought was interesting.

I guess we don’t all share the same interests.


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[denny]

These are commerical-level considerations. Seems unnecessarily complicated for homebrewing. It's like using a backhoe when all you need is a trowel, or even just a spoon. Just curious, what's the goal here? Is this a solution looking for a problem? If it's just playing around, totally cool, to each their own. Again, just curious. Cheers.

Exactly.

[denny]

Mostly just playing around in an attempt to improve extract from the mash. Just an effort in constant improvement, process refinement, etc.  With all else being equal, early returns indicate slowing the flow to a controlled, measurable constant gpm worked for me. (I’ve only used this method once so more experience in needed).

I believe the faster flow I was using caused the wort to seek a path of least resistance around the grain bed or channeling through it reducing the extract points I was getting.

The rest was just a report on feedback I received from installing a rotameter in the flow path which I was trying to better understand and thought was interesting.

I guess we don’t all share the same interests.


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If the wort was channeling, you weren't batch sparging correctly.