Homebrewers Association | AHA Forum

General Category => Equipment and Software => Topic started by: gmac on June 21, 2011, 03:05:35 PM

Title: Fermenter build questions
Post by: gmac on June 21, 2011, 03:05:35 PM
I've decided to build a bigger fermenter and I have a couple questions.  In particular, does the diameter of the vessel matter?  I know if it was a pot it would impact boil-off rates but in a closed fermenter, does it matter if the fermenter is tall and skinny or narrow and wide? 

I'm looking to build something of about 15 to 20 gal capacity and we've ordered a 4X8 sheet of stainless to get started.  But, the dimension is clearly one of the key points to consider before we start cutting anything. 
I'm lucky that I have a good friend who has a machine shop and is slow right now so we are going to have the steel rolled to dimension and then a seam welded. He has a very good TIG welder on staff so I'm not that concerned about the weld as it will be done well and ground.  We're also looking at having a cone rolled for the bottom and welded. 

The other consideration was, would it make any sense to have the entire fermenter made conical?  Instead of having straight sides attached to a cone, would it make sense to have it all as a cone and weld wedges on the exterior to bolt legs to.  The lid will likely be formed with an o-ring groove and clamps to hold it in place.  Any other thoughts?  I've looked at some on-line and I don't know if I like how the lid attaches on some of them.
Thanks for the advice.
Title: Re: Fermenter build questions
Post by: denny on June 21, 2011, 03:17:49 PM
Fermenter geometry does have an affect on fermentation.  A tall narrow fermenter will exert more pressure on the yeast than a wider shallower one.  My understanding is that will place more stress on the yeast and produce different flavors.
Title: Re: Fermenter build questions
Post by: gmac on June 21, 2011, 03:38:35 PM
I wonder what the commercial ones look like.  Anyone have a commercial fermenter that they can tell me the ratio of diameter to height?  Then, I could just scale down accordingly.
Title: Re: Fermenter build questions
Post by: tschmidlin on June 21, 2011, 04:09:27 PM
It does have an effect, but it should be pretty small at the 10-20 gallon scale.  It's not like you're talking about making it 10 feet wide and 1 inch deep, or 1 foot wide and 7 feet deep.  Within the normal range for the volume and shape you're proposing, there won't be too much difference.

I wouldn't go all cone, I think that would make it too big at the top and a weird shape to be easy to handle.
Title: Re: Fermenter build questions
Post by: bluesman on June 21, 2011, 04:26:25 PM
On a Brewstrong session, Jamil made note of the fact that fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast. Palmer agreed as well. Although, I'm uncertain as to how they confirmed this information.

I have a 14.5 gal conical fermenter that I've used to ferment 5 gal of beer and I have noticed and increase in esters from an aroma and flavor standpoint but this was based from batch to batch and not a side by side comparison. I really need to do duplicate back to back batches (5 and 10 gal) then do a blind tasting.
Title: Re: Fermenter build questions
Post by: richardt on June 21, 2011, 04:57:22 PM
Check this out:  http://www.toledometalspinning.com/hopper/default.php (http://www.toledometalspinning.com/hopper/default.php)

The cone should be 60 degrees (read that somewhere). 
It is steep enough to allow yeast and trub to slide and settle towards the apex of the cone (though you sometimes see pro-brewers whacking the larger cones with rubber mallets to try and get the yeast and trub to settle further down the cone).

Keep in mind that, given the same radius and height, the volume of a cylinder is 3 times that of a cone. 
You can ferment more beer in less space with a cylinder. 
This is an important consideration if you're using a keezer or refrigerator. 
To use a 27 gallon fermentor, you'd need 24 x 24 x 36 inches (minimum), preferably 26x26x38 inches or more.  See the Blichman website listed below (click on "data" tab).

If doing it from scratch, I'd basically copy the profile of a 20 gallon brew kettle and put a 60 degree cone on the base; basically giving yourself a 26.67 gallon fermentor (assuming you go with a flat lid). 
Consider using FermCap-S to limit the excessive krausen -- it'll help prevent blow-off problems.

Check out the 27 gallon fermentor Blichmann makes http://www.blichmannengineering.com/fermentor/fermentor.html (http://www.blichmannengineering.com/fermentor/fermentor.html)
Title: Re: Fermenter build questions
Post by: tschmidlin on June 21, 2011, 05:08:13 PM
On a Brewstrong session, Jamil made note of the fact that fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast. Palmer agreed as well. Although, I'm uncertain as to how they confirmed this information.

I have a 14.5 gal conical fermenter that I've used to ferment 5 gal of beer and I have noticed and increase in esters from an aroma and flavor standpoint but this was based from batch to batch and not a side by side comparison. I really need to do duplicate back to back batches (5 and 10 gal) then do a blind tasting.
How did they account for changes caused by the increased headspace?  There will be a lot more O2 left that can diffuse into the wort with the fermenter 1/3 full than when it is 2/3 full, especially if they are using straight O2.  It's just not as straightforward as doing two batches like that.
Title: Re: Fermenter build questions
Post by: bluesman on June 21, 2011, 05:22:44 PM
On a Brewstrong session, Jamil made note of the fact that fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast. Palmer agreed as well. Although, I'm uncertain as to how they confirmed this information.

I have a 14.5 gal conical fermenter that I've used to ferment 5 gal of beer and I have noticed and increase in esters from an aroma and flavor standpoint but this was based from batch to batch and not a side by side comparison. I really need to do duplicate back to back batches (5 and 10 gal) then do a blind tasting.
How did they account for changes caused by the increased headspace?  There will be a lot more O2 left that can diffuse into the wort with the fermenter 1/3 full than when it is 2/3 full, especially if they are using straight O2.  It's just not as straightforward as doing two batches like that.

Tom...it's been a while since I've listened to that session and I'd have to go back through the sessions i order to accurately recap the info. but I believe it's the Brewstrong session "Fermenters" on 9/7/2009. They made mention of head space and O2 levels as well. It's a dynamic environment but fermenter geometry and size play important roles on ester production. Check it out if you can get a chance.
Title: Re: Fermenter build questions
Post by: tschmidlin on June 21, 2011, 05:31:01 PM
Tom...it's been a while since I've listened to that session and I'd have to go back through the sessions i order to accurately recap the info. but I believe it's the Brewstrong session "Fermenters" on 9/7/2009. They made mention of head space and O2 levels as well. It's a dynamic environment but fermenter geometry and size play important roles on ester production. Check it out if you can get a chance.
I'll listen when I get a chance.  I have no doubt that it plays a role, but I am skeptical that there is much difference at homebrew volumes.
Title: Re: Fermenter build questions
Post by: gmac on June 21, 2011, 05:35:58 PM
So if I do my math properly, a 1.2 foot by 3 foot cylinder would have a volume of approximately 23 US gallons.  The diameter of a circle with a circumference of 4 feet would be 1.2 feet.  That way we start with one cut across the sheet of steel.  The volume of a cone 1.2 X 1.5 feet would be about 4 US gallons so the total should be pretty close to 27 gallons.  This is likely taller than the Blichman models (I already checked them out on-line looking for dimensions).  This is a bit bigger than I was looking for but I could always cut the ht down a bit.  Volume of a cylinder 2.5 feet high is 21 gallons and the cone adds 4 for about 25 total.  Still more than I was originally intending but probably workable with upside volume.

Does this make sense?  That's about a 2:1 ratio of ht to width.  
I'll try to remember to take pictures.

Now, how to boil 30 gallons???  And does Coleman make a 45 gallon cooler???  Who's gonna drink all this beer???
Title: Re: Fermenter build questions
Post by: richardt on June 21, 2011, 05:40:25 PM
How big is your fridge?  You're not going to be able to lift the thing when it is full.  Do you have some way of lifting or transferring it with pulleys/chains or overhead rack?
Title: Re: Fermenter build questions
Post by: denny on June 21, 2011, 05:46:38 PM
How big is your fridge?  You're not going to be able to lift the thing when it is full.  Do you have some way of lifting or transferring it with pulleys/chains or overhead rack?

Yep.  It's one thing to have a big fermenter...it's entirely another to be able to control the temp in a fermenter that size.
Title: Re: Fermenter build questions
Post by: gmac on June 21, 2011, 05:52:04 PM
My ratio of ales to lagers is about 10:1 so far.  It gets pretty cool here in the fall/winter/spring with ambient basement temps about 60 degrees.  I'm thinking that I would not be refrigerating this much.  If I wanted to do a lager, I'd be back to using buckets in the fridge but for ales, I'm thinking I would be good at least 9 months of the year.  Hopefully with bigger volume I will be able to get some volume ahead for the hot months (and with the airconditioner in the house running, the basement goes back into the 60's pretty fast).  I expect that this larger volume will produce more heat during fermentation than a smaller volume so I may be unpleasantly surprised though.
Is there a reason for refrigerating that I am missing?  I fully expect to have to rely on pumps to move wort/beer as I know this is far too heavy to lift.
Title: Re: Fermenter build questions
Post by: morticaixavier on June 21, 2011, 05:59:06 PM
Now, how to boil 30 gallons???  And does Coleman make a 45 gallon cooler???  Who's gonna drink all this beer???


there is that post about an 880k btu burner! I would think that, except for high gravity brews the coleman 100qt would do the trick even at 15-20 gallons batches. could be wrong on that though.

Title: Re: Fermenter build questions
Post by: tom on June 21, 2011, 07:35:45 PM
Tom...it's been a while since I've listened to that session and I'd have to go back through the sessions i order to accurately recap the info. but I believe it's the Brewstrong session "Fermenters" on 9/7/2009. They made mention of head space and O2 levels as well. It's a dynamic environment but fermenter geometry and size play important roles on ester production. Check it out if you can get a chance.
I'll listen when I get a chance.  I have no doubt that it plays a role, but I am skeptical that there is much difference at homebrew volumes.
+1
I think "they" now think that the effect is from hydrostatic pressure, thus the height of the fermenter, not the height:width ratio.
Title: Re: Fermenter build questions
Post by: Will's Swill on June 22, 2011, 12:24:08 AM
On a Brewstrong session, Jamil made note of the fact that fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast. Palmer agreed as well. Although, I'm uncertain as to how they confirmed this information.

I have a 14.5 gal conical fermenter that I've used to ferment 5 gal of beer and I have noticed and increase in esters from an aroma and flavor standpoint but this was based from batch to batch and not a side by side comparison. I really need to do duplicate back to back batches (5 and 10 gal) then do a blind tasting.

Not following you (no surprise, I haven't had a homebrew this evening).  If increased pressure causes more esters, then 10 gallons of beer should have more esters than 5, you seem to be saying your experience is the opposite.  ???

How did they account for changes caused by the increased headspace?  There will be a lot more O2 left that can diffuse into the wort with the fermenter 1/3 full than when it is 2/3 full, especially if they are using straight O2.  It's just not as straightforward as doing two batches like that.

Hey!  What happened to the magical CO2 blanket?   ;D
Title: Re: Fermenter build questions
Post by: tschmidlin on June 22, 2011, 04:58:54 AM
How did they account for changes caused by the increased headspace?  There will be a lot more O2 left that can diffuse into the wort with the fermenter 1/3 full than when it is 2/3 full, especially if they are using straight O2.  It's just not as straightforward as doing two batches like that.

Hey!  What happened to the magical CO2 blanket?   ;D
;D

The O2 in solution will be taken up really quickly by the yeast, allowing the O2 in the headspace to diffuse into the wort/beer before CO2 saturates the solution.
Title: Re: Fermenter build questions
Post by: Will's Swill on June 23, 2011, 01:01:46 AM
You got an answer for everything.   ;)
Title: Re: Fermenter build questions
Post by: gmac on June 23, 2011, 02:09:02 AM
You got an answer for everything.   ;)
He hasn't told me how big to make my fermenter yet. 
Title: Re: Fermenter build questions
Post by: bluesman on June 23, 2011, 02:29:34 AM
On a Brewstrong session, Jamil made note of the fact that fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast. Palmer agreed as well. Although, I'm uncertain as to how they confirmed this information.

I have a 14.5 gal conical fermenter that I've used to ferment 5 gal of beer and I have noticed and increase in esters from an aroma and flavor standpoint but this was based from batch to batch and not a side by side comparison. I really need to do duplicate back to back batches (5 and 10 gal) then do a blind tasting.

Not following you (no surprise, I haven't had a homebrew this evening).  If increased pressure causes more esters, then 10 gallons of beer should have more esters than 5, you seem to be saying your experience is the opposite.  ???



From my experience, when using my 14.6 gal Blichmann conical fermenter to ferment 5 gal vs. 10 gal of beer, there is an increased level of ester production due to a lesser amount of pressure applied to the yeast. Conversely, when fermenting 10 gal there is an increased level of pressure on the yeast, therefore suppressing (slowing) the ester production.

Title: Re: Fermenter build questions
Post by: tschmidlin on June 23, 2011, 05:33:16 AM
You got an answer for everything.   ;)
He hasn't told me how big to make my fermenter yet. 
I think you should make it as big as you like. ;D

You've got the 60 degree angle for the cone, which I think is a good idea.  You've got to figure out the height and width constraints and use that as your guide.  But if you're looking for a number, I wouldn't go less than 18" wide just for the stability.  I would probably do 20".

If you have a cone that is 18" at the top, it will hold 5.7 gallons.  The cylinder on top, 18" across and 12" high would hold another 13.2 gallons.  So if my math is right you've got 18.9 gallons, which is in your 15-20 gallon range.  I think there's enough space on a 4'x8' sheet to lay that out, but I could be wrong.  Figuring out the geometry of a cone laid flat is more geometry than I want to do right now. ;)
Title: Re: Fermenter build questions
Post by: tschmidlin on June 23, 2011, 05:37:48 AM
Not following you (no surprise, I haven't had a homebrew this evening).  If increased pressure causes more esters, then 10 gallons of beer should have more esters than 5, you seem to be saying your experience is the opposite.  ???
The confusion is in the wording.  When Ron said this:


fermenting 5 gal of beer in a 15 gal conical will tend to produce more esters than it would had you been fermenting 1o gallons of beer due to an increased amount of pressure on the yeast.

he meant that the increased pressure on the yeast in the 10 gallon fermenter reduces the esters.  It took me a second to get what he meant too.

I'm still skeptical that it is the pressure and not the O2.
Title: Re: Fermenter build questions
Post by: Will's Swill on June 24, 2011, 02:44:00 AM
Ah, right.  I read it wrong.  I'm tracking now.
Title: Re: Fermenter build questions
Post by: bluesman on June 24, 2011, 12:27:34 PM
Ah, right.  I read it wrong.  I'm tracking now.

Sorry for the confusion...I was only on my second cup of coffee that afternoon.  ;D
Title: Re: Fermenter build questions
Post by: gmac on June 24, 2011, 01:44:11 PM
I think you should make it as big as you like. ;D

You've got the 60 degree angle for the cone, which I think is a good idea.  You've got to figure out the height and width constraints and use that as your guide.  But if you're looking for a number, I wouldn't go less than 18" wide just for the stability.  I would probably do 20".

If you have a cone that is 18" at the top, it will hold 5.7 gallons.  The cylinder on top, 18" across and 12" high would hold another 13.2 gallons.  So if my math is right you've got 18.9 gallons, which is in your 15-20 gallon range.  I think there's enough space on a 4'x8' sheet to lay that out, but I could be wrong.  Figuring out the geometry of a cone laid flat is more geometry than I want to do right now. ;)
You make a good point about it being at least 18" wide for stability.  I was going 14.5 just because that was basically the diameter from a 4 foot circle.  But, we can probably lay it out another way and minimize the waste.  I've also decided to keep my old fridge and use it as a fermentation chamber (gotta buy a temp controller).  Just bought a 17.5 cu ft freezer yesterday to hold kegs so the fridge will now be free.  Need to make sure that what I build will fit inside the cabinet of the fridge. 
Title: Re: Fermenter build questions
Post by: tschmidlin on June 24, 2011, 06:22:51 PM
I think you should make it as big as you like. ;D

You've got the 60 degree angle for the cone, which I think is a good idea.  You've got to figure out the height and width constraints and use that as your guide.  But if you're looking for a number, I wouldn't go less than 18" wide just for the stability.  I would probably do 20".

If you have a cone that is 18" at the top, it will hold 5.7 gallons.  The cylinder on top, 18" across and 12" high would hold another 13.2 gallons.  So if my math is right you've got 18.9 gallons, which is in your 15-20 gallon range.  I think there's enough space on a 4'x8' sheet to lay that out, but I could be wrong.  Figuring out the geometry of a cone laid flat is more geometry than I want to do right now. ;)
You make a good point about it being at least 18" wide for stability.  I was going 14.5 just because that was basically the diameter from a 4 foot circle.  But, we can probably lay it out another way and minimize the waste.  I've also decided to keep my old fridge and use it as a fermentation chamber (gotta buy a temp controller).  Just bought a 17.5 cu ft freezer yesterday to hold kegs so the fridge will now be free.  Need to make sure that what I build will fit inside the cabinet of the fridge. 
That sounds great.  Now that I'm a bit more awake . . . lay the cylinder out long ways along the long edge, and you still have 36" by 96" to play with (plus part of that is still 48" wide).  If the cone is 12" radius at the top, then laid flat the max you need is a 32" circle.  If I've laid it out right in my head, I think you might actually have enough there to make two of them that size, and maybe one lid.
Title: Re: Fermenter build questions
Post by: gmac on August 04, 2011, 07:08:14 PM
I hate leaving posts without closure so here's what happened.
My friend's machine shop got very busy, very quickly and I now own the worlds flattest fermenter.  Basically, I have a 4X8 sheet of stainless and that's it.  Guess this will have to wait until things slow down.   :-[
Title: Re: Fermenter build questions
Post by: dcbc on August 05, 2011, 12:43:47 AM
At that batch size, I don't think it makes much of a difference. I have been fermenting in a tall, narrow 15 gallon Cornelius keg for the last couple of years without any noticeable effect on flavor from my smaller batches in carboys and buckets. The issues with hydrostatic pressure don't tend to really impact flavor until the vessels are much larger.