Temperature Control

[irish_goat]

On a similar note, is there any decent way of chilling a fermenter that doesn't involve a fridge? I could probably get my hands on an old under the bar beer chiller. Maybe hook that up to an immersion coil?

[DEMPSEY]

That will work just another item to be clean and sterile though.

[irish_goat]

Would there be a way to work a coil around the outside of the fermenter and chill that way?

[DEMPSEY]

Yes. If you are using a plastic bucket it will not be as effective as a stainless steel one but what I would do is use copper tubing and lightly flatten it so more of the copper surface touches the side wall of the fermenter. To stop it from falling away you can tack on support struts to the flattened pipe so it holds in place or you could keep it in place with a layer of insulation foam. To best do this would be to use a larger second container wrap the pipe around the FV and sit it in the second larger vessel and fill the cavity with expanded foam.  

[irish_goat]

I have a few kegs that I'll eventually get round to cutting open if they'd do the trick.

Or I could buy this. http://www.a1barstuff.co.uk/single-cooler-p-400.html 

[DEMPSEY]

How much are they paying you now

[irish_goat]

Not that much! 

[JD]

...but what I would do is use copper tubing and lightly flatten it so more of the copper surface touches the side wall of the fermenter. 

You've identified the problem but the solution proposed will be little better than a normal round pipe. It'll still be just copper pipe touching keg sides at a point here and a point there.
What's needed is a good strong thermal connection between sides of keg and copper pipe. So, taking a hint from a Tesco's  own brand wine cooler, put the FV into an outer vessel that has a larger diameter (e.g. a 25L fermenter sitting in a 33L fermenter or a 50L beer keg sitting in an oil drum). Fill outer vessel with water and chill the water with an immersed coil.

/J

[Dr Horrible]

Any solution with the cooling on the other side of a plastic or glass vessel is going to have a very slow response time though because the heat transfer rates across both plastic and glass are very poor compared to copper or stainless.
I've actually just got going a full temperature control system using a stainless steel coil in the fermenter itself for the cooling element and it's working very well, getting really tight temperature control - I've also installed a stainless  steel thermowell (as you can see I love shiny equipment) centrally in the fermenter so I'm also getting an instantaneous temperature reading - with the two of these I'm getting a very fast response to temperature fluctuations and it only takes a quick blast of cooling (30seconds to a minute of water flow) to bring the temperature back to the setpoint.
Although I won't deny that I would like a fridge (although mostly for lagering), I think that option has flaws - from looking at temperatures during a fermentation in the center of the fermenter and at the fermenter wall, during the critical time (24-48hours) when the temperature starts to rise quickly the central temperature can be 3-4 degrees higher than indicated on the fermenter wall.  Put this together with the slow response time of a fridge and the fact that a probe on the fermenter wall may just be reading the ambient temperature if it's not properly insulated, and you may have actual fermentation temperatures higher than what you think you are getting.
I'm pretty new to brewing (done about ten batches) and mostly have been sucking all the information I can from this website (couldn't have installed my STC-1000 controller without the info on here) so usually have very little to contribute but as I work as a process engineer and do this sort of work at large scale I thought I'd get my spake in!

[JD]

If you're doing temperature controlled fermentation you need to place the temperature probe in the wort and not on the side of the FV. This is a fundamental really.
As regards the response time of a fridge, this is not likely to be significant. The wort will not change temperature that quickly while fermenting. The fridge, in the meantime, will be simultaneously producing lots of cold air. This, in turn, will relentlessly be sucking the fermentation heat right out of the brew. While no thermal system will keep perfect pace with the object being cooled, the lag will be very minor, relatively speaking.

Almost every homebrewer that does temperature controlled fermentation uses a fridge or freezer and something like a STC-1000 or PID controller to manage it all and all to very good effect.

/JD

[LordEoin]

I fyou insulate the sensor enough against the side of the FV I think it's fine.
I use a pad of packaging foam and it seems to do just as good as having the sensor in the wort

[Dr Horrible]

Yeah, I shouldn't really be commenting on fridges at all because I've never used one for a fermentation (I've got fridge envy) so if you have a thermowell and the fridge is controlling fine then that's that really.  However, I don't think everyone with a fridge is using a thermowell, any books I've read recommend doing as LordEoin said above, taping to the wall and insulating and I suppose that is where I think there could be a problem because you're getting the temperature of the edge of the fermenter which will definitely be cooler than the centre.  But if no-one is seeing a problem then I guess there isn't one.
However, I can say though that a cooling coil is WAY more efficient time and energy wise than a fridge - you can just see that if you compare cooling a wort from the boil using an immersion coil compared to putting your wort in the fridge - a cooling coil is about twenty times faster. Cleaning and sanitisation is very easy, I have everything mounted on my lid so just sanitise the same time I sanitise my fermenter.
So Irishgoats proposal of a coil with a beer chiller is probably the most efficient, but it's probably easier to buy a fridge (if you have the space!).  I've actually been trying to get a hold of a beer chiller for a while (currently recirculating chilled water), but haven't been successful so far, so Irishgoat if you're not using yours I'd be glad to buy if off you! 

[LordEoin]

any books I've read recommend doing as LordEoin said above, taping to the wall and insulating and I suppose that is where I think there could be a problem because you're getting the temperature of the edge of the fermenter which will definitely be cooler than the centre. 

During the bulk of fermentation the wort s in a state of constant movement. You're pretty much sure that the temperature of the wort at the edge of you FV is the same as that in the center.
Once the fermentation has slowed and the wort begins to chillax a little the temperature of the wort and the fridge will stabilize. Afterall you have a 23 liter bucket of liquid in this box of air.

A cooling coil or thermowell might be a better option, but honestly I don't see myself replacing the fridge.

[Garry]

Am I right in saying that the temperature stated on the yeast instructions is the ambient room temperature?

If so, then sticking the probe to the outside of the FV would be more accurate, wouldn't it? That's what I tell myself anyway.

[LordEoin]

no, the tempeature on the yeast packet would be the wort temp.