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evaporation rates
Posted: Fri Jul 13, 2012 5:48 pm
by divejunkscc
Is a 20 gallon kettle to big to do a 5 gallon full volume boil? Or does it really make a difference.Just trying to decide which kettle to put a valve on first.I have a 7.5 gallon pot too, but it looks really full with 6.5 gallons of water in it.Any thoughts?Thanks in advance.
evaporation rates
Posted: Fri Jul 13, 2012 5:53 pm
by JimF
7.5 is pretty small to do a full volume boil for a 5 gallon batch. I occasionally boil over when using a 10 gallon brew pot. I can't think of any real problems using a 20 gallon pot except needing long arms.
On Jul 13, 2012 6:48 PM, "divejunkscc" <
brew-equipment@crbeernuts.org (
brew-equipment@crbeernuts.org)> wrote:
Is a 20 gallon kettle to big to do a 5 gallon full volume boil? Or does it really make a difference.Just trying to decide which kettle to put a valve on first.I have a 7.5 gallon pot too, but it looks really full with 6.5 gallons of water in it.Any thoughts?Thanks in advance.
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Re: evaporation rates
Posted: Fri Jul 13, 2012 9:39 pm
by jjbuck
You're right Jim, you have to pay closer attention about boil over. I think a bigger pot allows for a more vigorous boil with less fear of boil over. Doesn't eliminate it completely but does make it easier.
JimF wrote:7.5 is pretty small to do a full volume boil for a 5 gallon batch. I occasionally boil over when using a 10 gallon brew pot. I can't think of any real problems using a 20 gallon pot except needing long arms.
On Jul 13, 2012 6:48 PM, "divejunkscc" <
brew-equipment@crbeernuts.org (
brew-equipment@crbeernuts.org)> wrote:
Is a 20 gallon kettle to big to do a 5 gallon full volume boil? Or does it really make a difference.Just trying to decide which kettle to put a valve on first.I have a 7.5 gallon pot too, but it looks really full with 6.5 gallons of water in it.Any thoughts?Thanks in advance.
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Posted: Sat Jul 14, 2012 7:06 am
by bf514921
with a 20 gallon pot are there concers with a 5 gallon batch being to small for the pot? or does the 20 gallon just make life realy realy easy or am i looney and should go have a coffe bender for breakfast
evaporation rates
Posted: Sat Jul 14, 2012 10:24 am
by hoboscratch
I use a keg for my boil kettle. What's that, 16 gal? I like having the extra capacity. Less worry of boil over.
On Jul 14, 2012, at 8:06 AM, bf514921 <
brew-equipment@crbeernuts.org (
brew-equipment@crbeernuts.org)> wrote:
with a 20 gallon pot are there concers with a 5 gallon batch being to small for the pot? or does the 20 gallon just make life realy realy easy or am i looney and should go have a coffe bender for breakfast
Brandon Franklin - The other Franklin
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Posted: Sat Jul 14, 2012 8:06 pm
by divejunkscc
So I could use the 20 gallon pot and there would be no more loss to evaporation than with the 7.5 gallon pot? I only wonder because of the larger surface area.
evaporation rates
Posted: Sat Jul 14, 2012 8:39 pm
by JimPotts
There's always going to be some difference, but not that much. In the very worst case, you'd just need to increase your pre-boil volume by a fraction.
On Sat, Jul 14, 2012 at 9:06 PM, divejunkscc <
brew-equipment@crbeernuts.org (
brew-equipment@crbeernuts.org)> wrote:
So I could use the 20 gallon pot and there would be no more loss to evaporation than with the 7.5 gallon pot? I only wonder because of the larger surface area.
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evaporation rates
Posted: Sun Jul 15, 2012 7:01 am
by carrisr
I think that geometry of the pot (height to width) may have more to do with evaporation than how full the pot is. So, yes, there will be differences between the two pots. You could always do a test boil with water and compare. That 7.5 gallon is not going to be ideal though if you are doing full boils for 5 gallon batches or larger. For reference, my batches are 2.5 gallon, and I use a 7.5 gallon pot. I still can get boil-overs very easy if I'm not watching. If you plan to do larger full boil batches you'll need to watch it like a hawk and probably use an anti-foaming agent. Not sure it's worth the extra grief since you already have an alternative.
On 07/14/12 21:06, divejunkscc wrote:
So I could use the 20 gallon pot and there would be no more loss to evaporation than with the 7.5 gallon pot? I only wonder because of the larger surface area.
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Posted: Sun Jul 15, 2012 9:54 am
by TappedOut
My take on it is that evap rate is a function of heat input. With a burner, a bigger pot may be slightly more efficient, (i.e., more heat from the burner goes into the wort vs. up in the air around the sides), but I doubt it's significant. With electric, even that doesn't matter. Basically it takes a certain amount of energy to vaporize a certain amount of water, called the heat of vaporization. For water, wikipedia tells me it's 2257 kilojoules/kilogram. One kilojoule is one kilowatt for one second.
http://en.wikipedia.org/wiki/Latent_hea ... porization
Posted: Fri Aug 03, 2012 11:10 am
by Matt F
Don't be scared to fill up your kettle. I boil 12 to 13 gallons in a 14 gallon kettle. It does boil over when I don't pay attention but you can get a good rolling boil going and can leave it once its stable. Burner probably makes a difference. I use a hurricane with great flame control. You can't tell from the picture, but this boil was strong. You can see I had a little boil over, but a hose down with water fixes that quick. You can also blow a fan across the top of the boil to keep the foam down. I also scoop that first bunch of foam off the top and toss it down the sink.
Posted: Sat Aug 04, 2012 6:34 pm
by bf514921
boils over when your not paying attention or busy drinking with aomeone hanging out while you brew
Posted: Sun Aug 05, 2012 12:23 pm
by TappedOut
Anti foam helps too. A very important step I learned when doing extract is to turn off (or way down) the burner when adding the first hop addition.
Posted: Sun Aug 05, 2012 1:44 pm
by brownbeard
I boiled 5 gallon batches in a converted pony keg for a decade.
Posted: Mon Aug 06, 2012 1:09 pm
by jjbuck
Skimming the foam early helps prevent boil-overs (like Matt said) also keeps you focused on the early boil.