Author Topic: Beer serving temp  (Read 2156 times)

Offline euge

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Beer serving temp
« on: November 22, 2012, 10:31:13 PM »
I got back from visiting the family and placed a 3 gallon keg of bitter into a bucket and chilled with frozen bottles for a couple hours. The water is 48F and the first couple glasses were exactly that temp. Tastes great. Now the beer is serving 10 degrees over the ambient water temp. Still awesome. maybe better. ;)

The water is to the top of the keg and over the level of the beer but I'm assuming there's some sort of convection? Why else would the beer warm up while the chilling water has remained the same temp?


And what temp do you guys serve beer at. mine usually is in the low 40's? I was raised with cold beer here in the South. Can't help it.
« Last Edit: November 22, 2012, 10:32:55 PM by euge »
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Offline erockrph

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Re: Beer serving temp
« Reply #1 on: November 22, 2012, 11:04:24 PM »
I generally keep my homebrew in the fridge door. I have my fridge temp set to 39F, so the door is probably a few degrees above that. If I'm tasting beer I'll usually let the bottle sit on the counter for 10-15 minutes before I pour, otherwise it goes straight from the fridge into a glass. I like them cold myself. I tend to nurse my beers over 30 minutes to an hour, so at some point I am consuming it at the optimal temp for the style :)

And as far as your temps go, the only thing I can think of is that maybe the beer in the line is warming up enough to raise the temp of a full glass. Other than that, no clue.
Eric B.

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Offline tschmidlin

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Re: Beer serving temp
« Reply #2 on: November 23, 2012, 01:43:50 AM »
Yeah, it could be a problem with it not being mixed.  If the outer edges cool that will make the beer denser and it will sink to the bottom, where the dip tube is.  Once you pull out the cold stuff you're left with the warmer beer above it.  I don't know if that is actually what happened, but maybe.

I like my beer cold too, for the same reason - it takes me long enough to drink most of them that by the time I'm done it's on the warm side of ideal.
Tom Schmidlin

Offline anje

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Re: Beer serving temp
« Reply #3 on: November 23, 2012, 01:34:35 PM »
I'm coming up with some crazy idea about there being a lot of pressure in the keg at first, which contributed to the chilling, and that now it's closer to equilibrated. Suppose that's not likely, is it?
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Offline tschmidlin

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Re: Beer serving temp
« Reply #4 on: November 23, 2012, 10:38:19 PM »
I'm not sure what you're getting at anje - are you saying the level of CO2 in the keg affected the chilling?  I don't think that would happen to any significant, noticeable extent.
Tom Schmidlin

Offline morticaixavier

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Re: Beer serving temp
« Reply #5 on: November 24, 2012, 10:59:15 AM »
if you reduce the pressure you also reduce the temp. so as the pressure drops the temp should actually get colder right? Obviously there is not enough pressure drop to see this in action. although last night I was brewing and it was a bit cold out but the propane tank had frost on the sides. This was convenient as it alerted me to the half filled state of the tank.
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Offline tschmidlin

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Re: Beer serving temp
« Reply #6 on: November 24, 2012, 12:33:20 PM »
if you reduce the pressure you also reduce the temp. so as the pressure drops the temp should actually get colder right? Obviously there is not enough pressure drop to see this in action. although last night I was brewing and it was a bit cold out but the propane tank had frost on the sides. This was convenient as it alerted me to the half filled state of the tank.
You are mixing different problems - in your propane tank, the change in temperature is not caused by a change in pressure, it is caused by evaporation of the liquid propane in the tank. ;)

For a closed system like a keg the equation is PV=nRT, where n and R are constants.  For a keg V is essentially fixed, so there is no realistic way to change the pressure in a keg other than by changing the temperature.

If it is not a closed system, the equation is PV=nRT where R is a constant.  If you change the pressure by venting the keg you are changing n (the amount of gas) and there is no need to vary V or T.

If you change the pressure by CO2 dissolving into beer in the keg then it is not a closed system and you are still changing n.  The ideal gas law can only be applied to the headspace of the keg.
Tom Schmidlin

Offline euge

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Re: Beer serving temp
« Reply #7 on: November 24, 2012, 01:16:33 PM »
I really think it was convection. Cool beer from the sides gently settling towards the bottom which would subsequently be pulled out during each pour. I overindulged to be sure and drank more of the delicious brew than normal. The frequency of the pours outdid the chilling rate.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline mtnrockhopper

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Re: Beer serving temp
« Reply #8 on: November 27, 2012, 07:56:25 AM »
Yeah, it could be a problem with it not being mixed.  If the outer edges cool that will make the beer denser and it will sink to the bottom, where the dip tube is.  Once you pull out the cold stuff you're left with the warmer beer above it.  I don't know if that is actually what happened, but maybe.


This, or some similar partial cooling scenario, would be my guess.
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