Force carbing at room temp

Ok, I'm new to kegging and I have a question about force carbing.

I will be conditioning the kegs in my fermentation chamber for 2-3 weeks at 65 degrees. According to the charts, i should use 25-30 lbs. of CO2 to get it to the proper carbonation (2-2.5ish).

But what happens after two weeks when I put the kegs in the kegerator and drop the temp to around 40? Should I drop the pressure to around the recommended 12ish lbs for that temp? When I fill the keg to 25-30lbs, should I just disconnect the tank? Do I have to add more CO2 eventually? I just don't want over/under carbonated beer, thanks!

I would leave the gas on them, personally. Yes, when chilling the kegs you'll want to lower the pressure to serving.

So, is there really any point in getting the PSI up to 25-30 for a couple weeks if you're only going to lower it when you chill it? It seems like I should just leave it at 10-12 to save gas.

it will take twice as long at 10-12psi. Warm temps take longer to absorb CO2. You're not wasting that much gas as the headspace is minimal in a mostly-full keg.

Ok, just to be clear, follow the recommended PSI for 65 degrees (25-30ish). It's ok to leave it that high for 2-3 weeks? What happens if it dips to say 20PSI, should I add more CO2? Then drop it to recommended PSI for 40 degrees and chill. What happens if the pressure drops then? Is it just going into solution or, again, should I add more CO2? By the way, thanks!

PhreeBeer said:

So, is there really any point in getting the PSI up to 25-30 for a couple weeks if you're only going to lower it when you chill it? It seems like I should just leave it at 10-12 to save gas.

Click to expand...

At room temperature, you'll NEVER get up to your desired carbonation level with 10-12psi - at best, it will equalize at around 1.4-1.5 volumes, which is very undercarbed for nearly any style- in fact, that wouldn't be much more CO2 than will be remaining in your beer after fermentation alone.

http://www.kegerators.com/carbonation-table.php

PhreeBeer said:

Ok, just to be clear, follow the recommended PSI for 65 degrees (25-30ish). It's ok to leave it that high for 2-3 weeks? What happens if it dips to say 20PSI, should I add more CO2? Then drop it to recommended PSI for 40 degrees and chill. What happens if the pressure drops then? Is it just going into solution or, again, should I add more CO2? By the way, thanks!

Click to expand...

You seem to misunderstand the ways of force-carbonation.

The charts and rules all assume you're going to LEAVE it on that pressure for a period of time to allow the CO@ to equalize. You don't just hook it up at 30psi for a moment, disconnect and let it go. No, you need to leave it for a couple of weeks at the directed pressure given the temperature of the liquid.
Unless you have a faulty regulator, or an empty CO2 tank, once you set it at a given pressure, it will keep pushing out that pressure the entire time, and will keep adding more CO2 to your beer until you reach equilibrium.

Moreover, using CO2 at a higher pressure won't change the total amount it takes to carbonate the keg. It doesn't matter how hard it's pushing, we measure in VOLUMES of Co2, which compares how much Co2 would otherwise fit in the space the beer occupies if it was at "standard" pressure (sea level atmospheric). Pushing several times this amount into solution is what makes beer fizzy, not the pressure or speed at which it traveled to get there.

Ok, so leave it connected and it will stay at that PSI for weeks. Before I put it in the fridge do I purge the headspace and knock it down to 10-12psi? Obviously step by step instructions would be good for me.

Carbonation is a function of temperature and pressure. The colder beer is, the more easily CO2 will dissolve into it and the lower the pressure needs to be and vice versa. This is why they have a handy chart to follow. As for step by step, follow the chart end of story. Once you chill the beer pour a glass first and see where you're at. If the pressure is too high and it pours to fast/vigorously, then vent some pressure. You should be fine though, since the pressure inside the keg will drop along with the temperature. Have you ever put a warm, half full bottle of water in the refridgerator? It shrinks and colapses in on itself becasue the drop in temperature casues a drop in pressure.

No one seems to be addressing the key issue, which is the drastic change in temperature. Does going from 30PSI at 65 degrees down to 40 degrees require that I purge the tank and set the regulator to 12PSI to get to the proper serving carbonation??? Obviously I'm new to kegging, but will someone please DIRECTLY answer the question without resorting to science, thanks.

PhreeBeer said:

No one seems to be addressing the key issue, which is the drastic change in temperature. Does going from 30PSI at 65 degrees down to 40 degrees require that I purge the tank and set the regulator to 12PSI to get to the proper serving carbonation??? Obviously I'm new to kegging, but will someone please DIRECTLY answer the question without resorting to science, thanks.

Click to expand...

Step by step instructions are only good for one single situation. It makes sense you understand WHY they work.

Yes, when you go to a lower temp, turn off the gas (either turn off the valve or just disconnect from keg), purge the headspace of the KEG, turn down to serving pressure, and reconnect. A minimal amount of gas will flow in until it chills, then it should reach equilibrium again.

While it's chilling, however, CO2 will come out of solution into the headspace to reach a new equilibrium, resulting in a slightly lower volume in solution, which will take a nominal amount of time to reabsorb when chilled.

Alternatively, disconnect entirely after your holding time at 65F, 30psi (2-3 weeks is best, but the first week will see the biggest jump in volumes), then chill with the CO2 off, which will cause the equilibrium beer to absorb the remaining CO2 in headspace until equilibrium. Assuming the keg is nearly full, this will not be that much additional CO2, and will not overcarb while dropping from 30psi to ~12psi in headspace. Then when the keg has reached 40F, put the gas back on to serve. This is more efficient and won't necessitate purging again.

PhreeBeer said:

No one seems to be addressing the key issue, which is the drastic change in temperature. Does going from 30PSI at 65 degrees down to 40 degrees require that I purge the tank and set the regulator to 12PSI to get to the proper serving carbonation??? Obviously I'm new to kegging, but will someone please DIRECTLY answer the question without resorting to science, thanks.

Click to expand...

I've never carb'd warm in the keg like that , But I think yes.... as the temp in your beer goes down you will dial the Co2 down as well AND I think you will need to purge to re-equalize

now I have confused myself.... hmmmmmm

Step by step.

Decide what carbonation level you want. Take temperature of room. Look at chart. Set regulator according to chart.

Put keg in refridgerator. Check temperature of refrigerator. Set regulator according to chart.

Yes you need to turn regulator down. It keeps providing the pressure you set regardless of temperature .the keg pressure will drop, but the regulator will push more to equalize where you set it

I regularly force carbonate at basement temps, 30 psi at around 60-65 degrees F for two weeks. When I transfer it to the kegerator and it has cooled to 40 degrees F, I vent the excess pressure and attach the kegerator gas, which is always set to 12 psi. Perfect carb every time.

Unless you have a lot of head space, purging should not be necessary. Won't hurt, but a small volume of CO2 at higher pressure in the head space will not have a great effect on 5 gallons of beer. As long as you turn the pressure down so that no new gas is going in, you'll be fine.

I have found that if I don't purge, the keg will rapidly pour a foamy mess for the first few beers. If I purge, the first pour is usually perfect. Everyone's system is a little different, there are a lot of variables.

Ajgeo said:

Everyone's system is a little different, there are a lot of variables.

Click to expand...

Yeah, I've found that over the time I give the keg to chill (a day or two) the pressure reaches equilibrium.

. . . and I save 2 cents worth of CO2