I'm at the limit of my mash tun...

[Rob2010SS]

Working on a recipe for an imperial stout. I wanted 12 gallons of finished product into the fermenters. However, my mash tun is my limiting factor.

I have a 20 gallon mash tun.

If I target 8 gallons of finished product, that takes up approx. 16 gallons of space.
If I target 10 gallons of finished product, that takes up 20.12 gallons of space.

The most I could do is 9 gallons given my mash tun size.

My question is this: Would there be a point in increasing my batch size to 9 gallons?

I can fit 6 gallons in my unitank which would leave me about 2 gallons left over after my 1 gallon of losses with the hoses, pumps and chiller. Is there a point in keeping this extra 2 gallons or should I just cut down my batch size to not have left overs?

EDIT: I should add that this stout will go into a barrel after fermentation as well. Not sure if that changes any opinions. It will be in the barrel for 3 weeks.

 

[eric19312]

What gravity are you shooting for? Just mash thicker until it fits. Then you will sparge longer to get target boil volume.

 

[Rob2010SS]

What gravity are you shooting for? Just mash thicker until it fits. Then you will sparge longer to get target boil volume.

Yep, I could do that. But my problem is still there - what do I do with that small amount of extra volume? Is it worth keeping that or am I better off scaling down so that everything fits and not have to worry about it?

 

[eric19312]

Just make 12 gallons into your fermentors like you originally intended.
That would mean you want about 13 gallons post boil, and about 14.5 gallons pre boil. Or more if you are going to boil longer for higher OG.

Say you use 45 pounds of grain and mash at 1.25 qt/lb. You should easily fit in your mash tun and be able to hit OG over 100. I have no issue getting to 1.080 with 16 gallons delivered to fermentor in a 15.5 gallon mash tun. Mostly I'm brewing 1.050 these days but I see no reason you can't make the full 12 gallons you initially wanted.

 

[Rob2010SS]

Just make 12 gallons into your fermentors like you originally intended.
That would mean you want about 13 gallons post boil, and about 14.5 gallons pre boil. Or more if you are going to boil longer for higher OG.

Say you use 45 pounds of grain and mash at 1.25 qt/lb. You should easily fit in your mash tun and be able to hit OG over 100. I have no issue getting to 1.080 with 16 gallons delivered to fermentor in a 15.5 gallon mash tun. Mostly I'm brewing 1.050 these days but I see no reason you can't make the full 12 gallons you initially wanted.

That's a good point. I was trying to keep the mash thickness at 1.35qt/lb but if I reduce that to even 1.1 like ive done in the past on my previous setup, might work. Not sure why I didn't think of doing that...

Does thicker mash help or hinder when it comes to efficiency? I thought i had a graph on that but can't find it

 

[Rob2010SS]

Just make 12 gallons into your fermentors like you originally intended.
That would mean you want about 13 gallons post boil, and about 14.5 gallons pre boil. Or more if you are going to boil longer for higher OG.

Say you use 45 pounds of grain and mash at 1.25 qt/lb. You should easily fit in your mash tun and be able to hit OG over 100. I have no issue getting to 1.080 with 16 gallons delivered to fermentor in a 15.5 gallon mash tun. Mostly I'm brewing 1.050 these days but I see no reason you can't make the full 12 gallons you initially wanted.

Dammit man! You're right! I can mash 49lbs of grain at 1.1qt/lb and it only takes up 17 gallons of space. Thanks for the tip

 

[eric19312]

Does thicker mash help or hinder when it comes to efficiency? I thought i had a graph on that but can't find it

According to this
http://braukaiser.com/wiki/index.php/Understanding_Efficiency#Mash_thickness

Thicker mash will reduce conversion efficiency. But I think you can compensate for that loss by mashing longer...do a 90 min mash.

When I want high conversion and ferment ability I’ll usually do an approximation of a Hochkurz step mash ...145 for 45 min, ramp to 160 and hold for 30 min, ramp to 170 hold 10 min.

 

[Rob2010SS]

I think I'll just plan on a 90 minute mash. Also I build my recipe based on 70% efficiency when I've been getting 80%, so that should put me close to target.

Thanks @eric19312

 

[Cyclman]

Or bring up your gravity with DME...

 

[doug293cz]

According to this
http://braukaiser.com/wiki/index.php/Understanding_Efficiency#Mash_thickness

Thicker mash will reduce conversion efficiency. But I think you can compensate for that loss by mashing longer...do a 90 min mash.

When I want high conversion and ferment ability I’ll usually do an approximation of a Hochkurz step mash ...145 for 45 min, ramp to 160 and hold for 30 min, ramp to 170 hold 10 min.

If I read Braukaiser correctly, he says that thicker mashes slow the rate of conversion. This means that if the mash time is too short, then a thicker mash will have lower conversion efficiency than a thinner mash. But, if you mash long enough, that will compensate for the slower rate of conversion. Subtle difference, but I'm a bit of a pendant.

Brew on

 

[eric19312]

If I read Braukaiser correctly, he says that thicker mashes slow the rate of conversion. This means that if the mash time is too short, then a thicker mash will have lower conversion efficiency than a thinner mash. But, if you mash long enough, that will compensate for the slower rate of conversion. Subtle difference, but I'm a bit of a pendant.

Brew on

I read it same way which is why I suggested longer mash.