Setting fermenting temp...

Put the probe up against your bucket, fold over a strip of bubble wrap a few times to insulate it from ambient temp, and duct tape the hell out of it to the bucket. That should get you a fairly close reading of your actual liquid temps.

 

i usually keep my fridge 4-6F below my intended fermentation temp for the first 48 hours. after that, i pull the fermenter out of the fridge and let it sit at ambient cellar temps (68-72F). Ester production happens within the first 1 to 2 days of fermentation while yeast is in the growth phase. Outside of that temperature controls fusel alcohols. It's important to monitor post growth phase temperatures (for temperatures getting too high) for the mentioned point but keeping a specific temperature isn't necessary.

 

What do you ferment in?

 

I have found this technique to be fairly consistent.

This also emphasizes the need to chill to pitch temp or even one or two degrees cooler. Once the yeast go to work, the battle of the temps begin. If you lose control of your primary temp at start-up it takes a while to bring it back down.

 

My favorite method with carboys.....

1. Buy a thermowell and a two hole stopper.

http://www.brewershardware.com/16-Stainless-Steel-Thermowell.html
http://morebeer.com/products/stopper-65-drilled-1-38-hole-14.html

2. Insert thermowell and airlock into two hole stopper.
3. Insert thermowell, airlock, and stopper assembly into carboy.
4. Insert Ranco temperature probe into thermowell.

Now you are measuring the temperature of the fermenting wort and automatically adjusting your temperature controller to maintain it.

If this is not an option and you want to guesstimate what temperature difference there is between wort temperature and ambient temperature, then during the most active part of fermentation, I've experienced temperature increases in the range of 3-10F. Beers with a higher OG, yeasts that are fast fermenters, and yeasts that like warmer fermentation temperatures usually are on the higher side of that 3-10F range. Back when I was doing this, I normally would set my ambient temperature for about 5 degrees lower than my desired fermentation temperature. I'd leave it this way for about 3 days and then start ramping my fermentation temperature up to a diacytel rest for another 3 days and then ramp it back down to the original fermentation temperature for the remainder of primary fermentation.

 

I set my fridge to average 6 degrees lower than my intended fermentation temp, with the probe reading the fridge air, not the fermenter. But I also use a heat wrap on the fermenter, with its own controller and its probe in a thermowell in the fermenter. This second controller gets set to the intended fermentation temp. So the fridge is providing the ambient temp, and the heat wrap is supplementing the heat generated by the fermentation, when necessary.

If I just had a fridge and the one controller, I'd probably start out with a 4-5 degree difference between fridge and intended fermentation temp, and adjust a couple times a day if necessary.

 

Thinking about going and picking these up at my LHBS. What about blow offs?

 

I think I'm going to find a rubberband that will do the job. Duct tape is always kind of fickle when working with cold/wet surfaces.

 

I had lots of luck setting my controller to 59F, wrapping above like Jeb suggested, and using a 15 watt light bulb and shop light iinside the fridge. The fridge sits outside in ambient 30F weather and it stayed within 1F for me for a week.

 

With a bucket you can use koopa's method or just drill a second hole in the lid and use a tight fitting stopper. I made my thermowell from the diptube of a ruined keg, or just use some 1/4" copper tubing with one end sealed.

 

I haven't had any yet since using them so I can't really comment on it.

 

I made a thermowell with a blow off. I drilled out a solid stopper to accept a 3/4" PVC pipe. I used a tee and off the branch it goes into a bucket. The top of the tee I used a 3/4 pvc x 3/8 npt bushing. I threaded a 3/8 compression fitting into the top of the tee and used 3/8 copper that was soldered closed on one end for the thermowell

 

If you only ferment one batch at a time you can use a thermowell in the fermenter. There's a bit more of an art to fermenting different batches at different stages of fermentation. Some of it will depend on the type of freezer you use. I use a chest freezer the temperature is pretty stable from one end to the next. Sometimes when I add a new batch and want to lower the temperature for its initial fermentation, I have to be concerned about stalling the fermentation of my other beers. I have done different things to accommodate them. I have insulated the fermenters that are later in the fermentation cycle. This simply doesn’t work that well. Withing a few hours the insulation become ineffective. I have removed them from the freezer for a while and cooled my brewing area with the air conditioning. That works okay, but a bit of a pain in the ass, and causes me to run the AC a lot (Luckily my "brewery" is in a garage apartment). I have added a heating pad on one side of the freezer and run it simultaneously with the freezer. This works pretty well, but they fight each other so it’s a waste of electricity and it’s impossible to regulate the temperatures exactly. I'd like more freezers, but the wife and the expense stand in my way at this point in time.

 

How high can you set the temp of a refrigerator? If you wanted to do a belgian style, where you wanted to get the temps up in the mid 70s, can that be done? I'm doing a tripel right now and just leaving it at room temp and hoping that it will heat itself up, but I'd like to have more control the next time I brew one.

 

With a two-stage controller, you can cool and heat (this time of year where I live, it can be 30s-40s at night and 60s-70s during thr day, so there's a window where I need both heating and cooling). People use all sorts of heaters in fermentation chambers. There are brew-belts and heating pads sold specifically for this purpose, but you can also DIY a solution. I have a light socket and bulb screwed to the lid of an empty paint can. Lid goes on, bulb turns on when the call for heat comes, and the can heats the chamber up.

 

The upper limit of fermenting temp in a fridge is only limited by the outside air temp.

If you want to ferment at 78, then obviously you must have an outside air temp near or above that (remember, fermentation creates heat). Example: If the outside air temp is 90, you could set the controller to maintain a temp inside the fridge between 68 to 78. Once stabilized that would give you a wort temp around 73 before the fermentation takes off. As fermentation decreases, you would slowly raise your spread.

The thermostat of the fridge is normally set between mid and max (35'ish), the controller just cycles the fridge on/off as determined by its probe (same as if you unplugged it). When running, the compressor is always full speed, creating an output near zero degrees. Ideally you want the compressor to cycle every ~60 minutes so the wort spends as much time above the target temp as below. This is exactly how your home fridge works. I find it pretty easy to keep the brew within one degree.

 

I use buckets also so I don't use a thermowell. Before I put fermenting beer in my chest freezer I tested it with water. I taped the probe to the side of the bucket and covered it with bubble wrap. I tested the temperature of the water 4 times a day at different times over a 3 day period. It was never more than 1 degree different from the temperature on the controller. Most readings were exactly the same as the controller temp. Not saying you shouldn't use a thermowell just saying the probe on the side of the bucket covered with some insulation works good.