wildwest450

Recipes 

I've done temp controlled fermentations for the past two years and have tried it all. The best results have come from simply duct taping the probe halfway down the fermenter.

Sometimes simpler is best.

bigjoe

Recipes 

Basically once the feremntation starts there isn't a swing, well its on the up side of the swing. Thats why wildwest and I are saying to smack the probe to side of the fermenter. I insulate the probe to keep ambient air away and get as accurate reading of the feremnter as possible. With all the mass from the beer the outside of the ferementer will be close to the acutal temp of the beer.

The temp is going up and the time it will take to warm up a box that is already cool, then to warm a jar of water that is cool and not generating any heat may allow the ferementer to get too hot.

Each feremntation is going to be slightly different. If it were the same I might be on the side of keeping the air temp at a fixed temp 5-10 degrees below what the you expect the beer to be at and calling it good.

I'm specifically talking about the first day or 2 of active feremntation. For some that might be 4 days after it is in the feremnter, or it might be 6 hours like the Dunkelweisen I did last wekend.

jgbrown

Recipes 

Amen. I do this as well.

jmansfield

Recipes 

Sure, measuring and controlling the surface temperature of your carboy will provide some level of control of the fermenting wort temperature. A little insulation on the probe doesn't hurt either. Trouble I found was that this still does not provide a great indication of what is occurring inside those thick glass walls. With a stopper thermowell and digital temp recorder I found a +3 degF rise during the exponential phase that was not detected by the surface probe. I think this is why some of my beers still get that "homebrew" flavor - fusels and esters. Here is a link to my latest effort to improve control, enjoy,

http://www.homebrewtalk.com/f11/water-jacketed-fermentation-chamber-145194/

Hermit

Recipes 

I had considered drilling a hole through the stopper and forcing a probe through and sealing it up, but this makes more sense. I immediately pictured some old capillary tubing I got years ago at a refrigeration supply house. It will be more than stiff enough to force through without worrying about having to use sealer if I drill a slightly undersized hole.

Anyone ever drill the stuff they make stoppers out of? I know an old machinist trick is to freeze rubber before machining it. Will that be needed here?

jmansfield

Recipes 

Yep, you gotta freeze the gum rubber stoppers in order to drill them. And regular old freezer temps are not cold enough. You need to use dry ice or liquid nitrogen. I have had pretty good luck using a torch and heating the end of tube to cherry red and then pushing it through the stopper - a little stinky and sticky mess but it worked.

IMHO, an easier way to control fermentation temp is to submerge carboy in water and temperature control the water - using either your freezer/ fridge or some sort of water chiller unit (I am using an Ice Probe). I have found that the fermenter temps will stay within 1 degF of the temp of the surrounding water. This is because the heat transfer rate from the glass carboy into water is 10x greater than it is into air.