evaporation rates

[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.

[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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[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.

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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[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

[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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[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.

[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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[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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[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

[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.

[bf514921]

boils over when your not paying attention or busy drinking with aomeone hanging out while you brew

[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.

[brownbeard]

I boiled 5 gallon batches in a converted pony keg for a decade.

[jjbuck]

Skimming the foam early helps prevent boil-overs (like Matt said) also keeps you focused on the early boil.