Method for maxing out 15g boil keggle

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I'm looking for a method to finish about 12 gallons of wort from a 15 gallon electric keggle. I ran a boil test last night and my boil off came out to 1.5 gallons per hour, exactly what it used to be when I was using propane. I haven't yet tried to boil 13.5 gallons of wort but I'm pretty darn sure that it won't go well! I also often prefer 90 minute boils on many recipes. In case you're curious, the overall goal is to double batch into a 30 gallon plastic conical, fermenting 24 gallons so I can finish about 23.25 gallons, which is 3 1/4 barrel kegs.

My thinking so far on this involves reserving a portion of the wort from the boil to start with, and then adding it back in later. The exact best way to go about this is the question I'm asking. Let's say for argument that the volume is 2 gallons. So I produce 13.5 gallons of wort, reserve 2 gallons, and start the boil with 11.5 gallons in the kettle; a perfectly safe boil volume. When should I add back the 2 gallons? Should I try to boil it for a while or just simply add it back at the end so that is has boiled some? Should the reserved wort be the same strength as the other wort or should it be the last runnings? The amount of sugar in the wort will have an affect on IBU calculations and hop utilization so would I be better off with the most sugar in the main boil?

Any ideas to point me in the right direction would be great!
 

bigdawg86

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Why not just use fermcap in the boil? Seems 1.5 gallons of headspace would work with fermcap and maybe a slow pour hop addition to prevent boilover? I'm no expert but fermcap keeps my boils in check!
 

mbobhat

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I'm looking for a method to finish about 12 gallons of wort from a 15 gallon electric keggle. I ran a boil test last night and my boil off came out to 1.5 gallons per hour, exactly what it used to be when I was using propane. I haven't yet tried to boil 13.5 gallons of wort but I'm pretty darn sure that it won't go well! I also often prefer 90 minute boils on many recipes. In case you're curious, the overall goal is to double batch into a 30 gallon plastic conical, fermenting 24 gallons so I can finish about 23.25 gallons, which is 3 1/4 barrel kegs.

My thinking so far on this involves reserving a portion of the wort from the boil to start with, and then adding it back in later. The exact best way to go about this is the question I'm asking. Let's say for argument that the volume is 2 gallons. So I produce 13.5 gallons of wort, reserve 2 gallons, and start the boil with 11.5 gallons in the kettle; a perfectly safe boil volume. When should I add back the 2 gallons? Should I try to boil it for a while or just simply add it back at the end so that is has boiled some? Should the reserved wort be the same strength as the other wort or should it be the last runnings? The amount of sugar in the wort will have an affect on IBU calculations and hop utilization so would I be better off with the most sugar in the main boil?

Any ideas to point me in the right direction would be great!
You can always just boil in two pots, the 2 gallons in a different pot.
 

jammin

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i really like your idea reserving/adding 2g of wort to the boil when there is room.

this makes me dream of a low specialty malt IPA allowing you to add your fingerprint by boiling the hell out of the reserved 2g. Id even use the first runnings for this to make it syrupy. you might be able to craft a fun caramelized addition to an otherwise boring wort.

i hope to hear back about your results
 

pdxal

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i really like your idea reserving/adding 2g of wort to the boil when there is room.

this makes me dream of a low specialty malt IPA allowing you to add your fingerprint by boiling the hell out of the reserved 2g. Id even use the first runnings for this to make it syrupy. you might be able to craft a fun caramelized addition to an otherwise boring wort.

i hope to hear back about your results
This would work, there is a Scottish ale recipe out there that uses this procedure.
 

Genuine

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I noticed with my 15 gallon electric kettle that I don’t get boil over or a huge reaction with hops when added. You’ll be fine with that amount of head space, just have to watch it right before hot break.
 

SanPancho

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Spray bottle with cold water to knock the foam down will keep you clean. Just means you have to watch it until hot break is done.
 

jakwi

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Maybe just boil the extra water separately, and add it in near the end of your boil, that way the addition doesn't kill the boil. It should only require a few minutes to mix well.

As an alternative have you tried to minimize your boil to a simmer? I started doing this with my ekeggle.

As I understand it isomerization of the AA happens at 175f increasing up to 212f. That being the case if you are simmering or hard boiling either way your temp should be above 200f, probably averaging 210f at sea level. ( I'm guessing here)

So why do you need a hard boil? Theoretically it will darken your wart, and reduce your volume. If neither of these two factors are part of your recipe goals you can probably reduce the boil to a steady simmer and achieve the same results without the increase boil off rate.

My rate is about 1 gal/hr. If your looking to maximize your capacity this could give you a little more, also a softer boil minimizes the risk of a boilover, and steam in your brewshop if that is a concern.

I set my control box to 100% to get it boiling, and then back it off to 60 or 70% Anyway it's just a thought.
 
OP
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I've been using the spray bottle approach before hot break and it's been working well. My PID is set at 67% to maintain a nice even boil and my boil off is exactly 1.5 gallons per hour. I haven't yet tried to truly max out the kettle yet, but I have some recipes written that will require a starting volume of 15.25g. In that scenario I'll leave out the last 2 gallons of runnings and add it slowly over the course of the boil. in reality there's no problem holding it until the very end and adding it then; I'll achieve the same end volume regardless of when it's added.
 
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