Do you stir whilst cooling?

[Kristoff]

Just doing an Exmoor Beast from the GW book, which is tasting mighty fine already I'm just getting my chiller ready and was wondering if anybody stirs whilst the chiller is in and doing its thing? I have always stirred on my previous four AG's, but i've never really thought wether you should or shouldn't.
It has occured to me that its probably best NOT to stir as you're always breaking up the cold break, but does stirring speed up the cooling process? What does everybody else do

[rick_huggins]

I read that you should stir for the first 10 mins to speed cooling but my last 2 brews (the only brews) had very little cold break material/trub therefore I won't be stirring again

[SiHoltye]

I don't fwiw. IC chills to pitching temp in 30-40 mins in summer.

[Totem]

I stir mine, got down to pitching in 6 mins.

[Cheshire-cheese]

I have a feeling that stirring not only distributes the cooling effect but I'm sure I've read somewhere that the trub collects in the middle of the vortex and drops to form a neat cone on the base of the copper.
Having said that, personally I leave it be and have a cuppa.

[CrownCap]

The cooling rate of an object (wort in this case) is proportional to the to the temperature difference between the object and the coolant (the cold water in the IC). So, the IC is at its most efficient (i.e. gives greatest rate of change of temperature) when the wort is hot. However, water (wort) is quite a poor thermal conductor and a cool 'blanket' of wort will form close to the IC, thus lowering its efficiency. By stirring you ensure that hot wort remains in contact with the IC, enabling to work at its optimum efficiency. That will result in a shortened cooling time.

I find stirring makes a big difference to the cooling time (particularly in summer when my tap water temperature is often close to my desired pitching temperature). I tend leave the wort for about 10 mins after cooling before transferring to the FV and it seems to come through fairly clear still.

[Philipek]

I stir but I'm really low tech and inefficient and dump the stockpot in a sink of cold water. I did it to speed up cooling which was taking ages but noticed, as Cheshire Cheese said, that the break and hop sludge are in a convenient little cone when it comes to syphoning. Next time I'll stop stirring at 60 degrees C, though.

However, this stirring thread put my in mind of Jamil Zainasheff's immersion whirlpool chiller which first inspired me to stir. http://www.mrmalty.com/chiller.php I had to read the write up about 3 times before I actually understood what was going on. Apparently it cools stuff about a million times faster than a counterflow chiller and increases hop aroma and flavour.

[mysterio]

I use the whirlpool chiller technique, it is quite fast, but I don't think it increases hop aroma personally.

[Spin]

I've only done a couple of batches of all-grain. But I have noticed that if I let it just sit without stirring. The water starts to come out of the IC felling cool after a while. Then if I stir the wort, the water coming out becomes warm again showing that it is exchanging heat more efficiently again. I am concerned about not having such a good cold break by stirring. But I can imagine it must aid cold break if you are cooling it quicker by stirring. As long as you let it settle afterwards.

[yashicamat]

I always stir mine right down to pitching temperature. I leave it for 5 minutes then to clear and never have any issues with crystal clear wort in the boiler.

[Big G]

Always stir for the temp to drop quicker, have tried both an seem to favour the stir.

[Kristoff]

I stirred for 7 mins down to 50deg, then left it for 10 mins, but the temp only dropped 5deg, so as i'm on a water meter I carried on stirring and got it down to 28deg in 10 mins, let it settle for 10 min and got lovely clear wort. That'll be my tecinique from now on

[cooldad]

Never stirred thought it would stir up the trub to much for draining off , but will give it a go next time and see what happens.

[yashicamat]

I think a lot of unnecessary emphasis is given to preventing trub from getting into the FV . . . my beers are always star bright with no traces of any off-tastes. If a bit gets drawn into the FV, it doesn't really matter IMO. Letting trub into a secondary or the barrel would be more of an issue perhaps, but in the FV it shouldn't be in there for more than a week. Perhaps the only time to be more trub-aware would be if doing a lager as I assume the lagering is done within the original FV?