Mash Tun - Dead space vs whats actually leftover

[fiveohmike]

Hey Guys,

Previously on my setup (MoreBeer 15g Mash Tun) I was leaving 1.25g in the tun because of the big deadspace in this setup.

I am having pretty bad efficiency even after starting to crush my own grain (.033 mill gap) and doing everything else so I am thinking I am getting hurt by the big deadspace (~55% efficiency right now) as there is always a lot of dark work left over.

So I got a dip tub ran to the center of the tun modified it so its sucking pretty much off the bottom. Now I am leaving 2 1/4 cups (0.15g) so that is fixed. Havent brewed with it yet so I am hoping this is the end of my efficiency problems.

So my questions:

1. You think I am on the right tract to fix efficiency issues?

2. How do I calculate this now? I need to account for the deadspace in my initial strike water calculations to get my grist ratio, but now I am getting out almost everything. I am using BrewSmith for Calcs, and have put in the deadspace water adjustment.

What I am thinking is:

Calculate my total water needed for the mash, get my strike water calculations and my batch sparge calc.

From there adjust 1.25g from the batch sparge water and put it in with the strike water to hit my grist ratio. Then batch sparge with the smaller batch sparge amount.

That sound right or am I overthinking this?

 

[pricelessbrewing]

You shouldn't have to adjust anything if you set beersmith up correctly.

Basically you're adding the deadspace to your losses after the mash, the mash thickness shouldn't need to be adjusted. I would try and see if you can lower the deadspace, as your limiting the surface area in contact between the grain and the water it can contact.

If you can't do that, then sure the adjustment you planned on doing might be the best bet, however the smaller sparge volume may introduce a loss of effecicency as well. Also be careful that adding the extra ~gallon doesn't cause you to get a stuck sparge.


Honestly sounds like you're on the right path, minimize your deadspace and get a good crush.

 

[fiveohmike]

You shouldn't have to adjust anything if you set beersmith up correctly.

Basically you're adding the deadspace to your losses after the mash, the mash thickness shouldn't need to be adjusted. I would try and see if you can lower the deadspace, as your limiting the surface area in contact between the grain and the water it can contact.

If you can't do that, then sure the adjustment you planned on doing might be the best bet, however the smaller sparge volume may introduce a loss of effecicency as well. Also be careful that adding the extra ~gallon doesn't cause you to get a stuck sparge.


Honestly sounds like you're on the right path, minimize your deadspace and get a good crush.

What if I just recirculate using my new pump?

 

[Gameface]

Dead space doesn't have to kill you efficiency. You can always add additional water to push out all that sugar infused wort and leave behind the extra water.

Are you sparging slowly enough and avoiding channeling? 55% with a .033 crush is really low. Have you checked you pH and verified your mash temp is accurate?

 

[fiveohmike]

Dead space doesn't have to kill you efficiency. You can always add additional water to push out all that sugar infused wort and leave behind the extra water.

Are you sparging slowly enough and avoiding channeling? 55% with a .033 crush is really low. Have you checked you pH and verified your mash temp is accurate?

Yep I verified the PH, mash temps were rock solid.

The only thing is I was leaving all that wort in the deadspace. The drain is also off to one side I was not pulling from the middle.

Now I am pulling from the middle and only leaving 2 1/4 cups. I am brewing tomorrow so I will report back.

 

[pricelessbrewing]

Recirculation should counteract the reduced exposure, and will usually boost 5-10% I think you'll probably get a bit more of a gain than usual.

My guess is if you do those things you should be back up to 70~

 

[doug293cz]

Dead space doesn't have to kill you efficiency. You can always add additional water to push out all that sugar infused wort and leave behind the extra water.

Are you sparging slowly enough and avoiding channeling? 55% with a .033 crush is really low. Have you checked you pH and verified your mash temp is accurate?

What you say applies for fly sparging, but even then it isn't quite correct. With a slow fly sparge, the concentrated wort below the MLT pickup point will only slowly, and inefficiently, mix with the lower concentration sparge water. The last bit of run off will be lower gravity than the wort remaining in the bottom of the MLT.

But OP stated that he is batch sparging. For batch sparging, the dead volume will greatly reduce your efficiency. Check it out in Kai's batch sparge simulator. His added dip tube should make a significant difference in his efficiency.

Brew on

 

[Gameface]

I appreciate the correction.

 

[fiveohmike]

Well I gained 12 points of efficiency last night. Went from 55% to 67%. Still gotta figure out what I am doing wrong.

At 0.036 mill gap last night my grain looked a tad flourish, but I did not have a problem with stuck sparge at all.

Maybe I am not stirring vigorously enough. I did run the recirculation pump for the last 20 minutes just to get a feel for the pump, but I am not sure what the flow rate should be on recirc so I tried to get it down to almost a trickle with the pump valve barely open.

I mashed at 152 for 60 minutes, but later this week I will try a 90 minute mash and check efficiency from there.

So confused. Maybe it will come down to mash tun design? Its very wide and not very tall for a 15g pot?

 

[rmyurick]

Is your temperature holding? If it's a wide bed, maybe it's a problem with distribution, i.e. all the sparge water going through a narrow path. Maybe a rotating sparge arm would help?

 

[fiveohmike]

Is your temperature holding? If it's a wide bed, maybe it's a problem with distribution, i.e. all the sparge water going through a narrow path. Maybe a rotating sparge arm would help?

I am batch sparging.

My temp dropped from 152 > 149 after 40 minutes, so I direct fired the mash tun while recirculating to bring it up to 152 for the last 20 minutes.

Im also starting to think I am not stirring vigorously enough. I stirred at mash in, 20 minutes, 40 minutes but did not stir before vorlaufing.

My stirring is not gentle but not super crazy vigorous.

 

[LandoLincoln]

What kind of drain system are you using? False bottom? Manifold? Screen tube?

 

[fiveohmike]

What kind of drain system are you using? False bottom? Manifold? Screen tube?

Its a false bottom:

http://www.morebeer.com/products/mash-tun-15-gallon-heavy-duty.html

14"H x 18"D

Deadspace is 1.25g, I leave 2 1/4 cups behind after draining.

 

[rmyurick]

Batch sparging costs you in efficiency. I get around 74-75% with a fly-sparge. I wouldn't expect anything more than 70% from a batch sparge.

 

[pricelessbrewing]

Batch sparging costs you in efficiency. I get around 74-75% with a fly-sparge. I wouldn't expect anything more than 70% from a batch sparge.

False.

 

[Bobby_M]

Seconded. Batch sparging efficiency is primarily tied to target OG and 75-80% is not unheard of. However, 67% is dandy. If you're not stirring in the sparge water very well, that's worth a few points. Also make sure you're calculating your sparge addition so that you reach your preboil without leaving any wort behind (intentionally).

 

[blizz81]

I assume we're talking brewhouse efficiency here. You can try to step down your crush a bit and see what happens, especially on something small on wheat / rye / specialty grains, just to see what effect that may solely have (if you reproduce process everywhere else as close as possible).

Depending on what you're using to dough in and stir, you could try a new utensil here too - I haven't used them personally but it sounds like the huge whisks people use on here might be the best bet. (I mention this because we were smack in the 60s for brewhouse eff for a while, and I tried 4 or 5 things at once - not ideal - to improve. Was already crushing fairly aggressive at I believe 0.030" or 0.032" and stepped it down to 0.028", and changed out a plastic brew spoon for a sturdy SS mash paddle. Those were the two biggest drivers I could see in the things we changed, and since then we've been 78-82%).

 

[stpug]

Batch sparging is perfectly capable of very high efficiencies (>80%) - system/process/crush dependent of course.

You should always start by looking at your mash efficiency which is easily measured with Preboil volume and Preboil gravity. Your brewhouse efficiency will always be lower than your mash efficiency. You mash efficiency should be in the ballpark of 90±5%. Once you've established your upper limit then you can see where you're losing points in your process that result in lower-then-desired brewhouse/fermenter efficiency (fermenter efficiency since that's how beersmith reports it). Many folks prefer to look at brewhouse/boilkettle efficiency instead, which is probably a better measure for comparison IMO.

If you find that your mash efficiency is on the low side, then you know that you need to look at your crush/lauter system.

 

[fiveohmike]

Batch sparging is perfectly capable of very high efficiencies (>80%) - system/process/crush dependent of course.

You should always start by looking at your mash efficiency which is easily measured with Preboil volume and Preboil gravity. Your brewhouse efficiency will always be lower than your mash efficiency. You mash efficiency should be in the ballpark of 90±5%. Once you've established your upper limit then you can see where you're losing points in your process that result in lower-then-desired brewhouse/fermenter efficiency (fermenter efficiency since that's how beersmith reports it). Many folks prefer to look at brewhouse/boilkettle efficiency instead, which is probably a better measure for comparison IMO.

If you find that your mash efficiency is on the low side, then you know that you need to look at your crush/lauter system.

Thanks for this info, I just ordered a refractometer to start to measure better at different stages like this.

I dont mind lower efficiency as long as I am consistent (I was consistent at 55%), but it just makes me feel like I am doing something wrong.

I will see how the second brew goes and will measure gravity at various stages to see what it looks like.

67% actually made me overshoot my OG on this brew by a bunch (as I was not sure what efficiency I would hit so I did not change the grain makeup). So the abv will be ~1.8% higher assuming i hit my FG target.

Also my volumes were dead on, hit 5.4g into the fermentor as calculated. I left ~4cups after the second batch sparge so I do not think that is my issue.

 

[rmyurick]

Of course the efficiency is also affected by how much water you sparge with. And you could split it up & batch twice, I guess.

 

[stpug]

Thanks for this info, I just ordered a refractometer to start to measure better at different stages like this.

I dont mind lower efficiency as long as I am consistent (I was consistent at 55%), but it just makes me feel like I am doing something wrong.

I will see how the second brew goes and will measure gravity at various stages to see what it looks like.

67% actually made me overshoot my OG on this brew by a bunch (as I was not sure what efficiency I would hit so I did not change the grain makeup). So the abv will be ~1.8% higher assuming i hit my FG target.

Also my volumes were dead on, hit 5.4g into the fermentor as calculated. I left ~4cups after the second batch sparge so I do not think that is my issue.

For sure, consistency is more important than efficiency once a person gets about 65% or higher. Below ~65% and, I believe, something needs to be figured out to bring the number up. It sounds like you're above that level so if you are finding consistency in your new process then I'd say roll with it until you decide you want to strive for a higher value.

IMO, mash efficiency is a great first step to seeing where your percentage losses are coming from.

 

[doug293cz]

I am batch sparging.

My temp dropped from 152 > 149 after 40 minutes, so I direct fired the mash tun while recirculating to bring it up to 152 for the last 20 minutes.

Im also starting to think I am not stirring vigorously enough. I stirred at mash in, 20 minutes, 40 minutes but did not stir before vorlaufing.

My stirring is not gentle but not super crazy vigorous.

It sounds like you are making good progress.

It's important to stir before vorlaufing in order to equalize the sugar concentration between the free wort and the wort still absorbed within the grain particles. This maximizes the sugar in the free wort, which is what you run off. It's equally important to stir in the sparge water thoroughly in order to get maximum extraction of sugars from the grain particles.

Finally, you should adjust your strike and sparge volumes in order to get equal run off volumes from the original mash and the sparge (ref).

Brew on