Fermentation Chamber Temp Settings

As I've not done this I'll be treading new waters with a learning curve no doubt.

I've seen many state they attach the temp probe to the fermentor, while some just monitor the air temp.

I had figured I'd do the latter as I intend on fermenting 2-3 standard (6 gal) batches, or at this time 2 standard and one smaller test batch of 2.5 gals.

I still haven't received my chest freezer from HomeDepot, but I don't have intentions of adding heat as it will be kept indoors. But a thought occurred to me that if I drop in a fermentor that's in the high 60's to low 70's, and set it to say 62*, it might be possible to actually have a lower fermentor temp, especially if I attached the temp probe to the fermentor.

If I use an air temp, and not a fermentor temp, what type of setting should I use if I want to ferment in the low 60's (62-64*)? I'm assuming there's at least a 5* temp difference, though I've always read that there's up to a 10* difference against ambient, though this typically seems to be when comparing it to room temp, and not that of a colder environment. Thermal mass of water makes a big difference I think.

I have my temp controller probe in a glass of water in the back of the chamber.

Pick up a cheap digital thermometer with probe and place it in there too. That way I don't have to guess what temp is actually being reaches with my temp controller.

I like to control every fermentation so I attach mine to the fermentor side. If 2 beers are the same batch you can put the probe between them. If you can avoid the analog temp controller. If it fails you will have a big mess and a ton of frozen beer....

I'm curious about dipping the probe into a glass of water. Is this because the water temp won't fluctuate as quickly as the air? What is the benefits of doing this?

The one thing that gives me pause to placing the probe on the fermentor itself is the initial time in which it attempts to reach the desired set temp. If I place my fermentor with 70* wort and set the temp for 62* how cold might it actually get the air inside? I'm assuming it could potentially be much colder, which may very well drop the wort temp even lower since I won't hook up any form of heat.

I'm uncertain by what you mean about the analog temp controller.

I bought the STC-1000.

You really want to control fermentation temperature not the ambient temperature in the chamber. Take a washcloth or something else to insulate from ambient and tape it to the outside of the fermenter. Or purchase a thermowell.


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What happens when I brew a beer, set it in and tape the probe to it, then a few days later brew another and swap the probe. As the second beer will be much warmer wouldn't it cause the other's temp to drop much lower?

Or do you just do one at a time? Maybe set to 62-64* for a week followed by a raised temp of 69-70* for the next week, and then pulling it so you can do the same with the next batch? My indoor temp is 74*.

I've usually kept my beer's temps in the low to mid 60's for 3+ weeks without raising the temp, and then pulling it to dry off a day or three beforehand.

Temperature control is most important during the growth phase of fermentation. Yeast will throw all those flavor compounds based on the temperature at that time. It's usually the first three days of fermentation. My rule of thumb is that cooler is better, if in doubt.

Of course, no matter what you do, you can't be at two temps at the same time, so plan your batches accordingly. As far as the first batch getting too cold due to the heat generated by the second batch, that's rarely that much of a problem. It is less than ideal but usually not noticeable if you have a healthy pitch of yeast and a good start. Keeping a super active fermentation at 65F results in a cooler temp of around 59F, in my case, and that won't cause the other to stop conditioning.

I use plumbers putty and just stick the probe to the side of the fermenter.

Am I understanding that a set temp of about 59* will typically keep your beer at 65*? And that's with the probe insulated to the fermentor?

Maybe I'll do my 2.5 gal test batch first to see how things go.

Not set to 59, the set temp will be within a degree or so of the wort temp. But if you check the ambient air in the cooler or removed the probe from the fermenter you'd see the air in the cooler has to be colder to keep the wort where it is. Thus,it's important to insulate the probe so it's reading the wort temp,not the air.

Just buy a thermowell for $12 off Brewers hardware and a Carboy cap if you use carboys, or another drilled stopper and drill another hole in your bucket lid if using buckets. A standard stopper drilled for an airlock is a tight leak free seal, just drill another hole for any size stopper in your bucket lid and shove a stopper in and the thermowell through the hole.

If your spending hundreds of dollars on a fermentation chamber dont cheap out on getting a proper measurement from the liquid.

Insulating it against the fermenter is the next best thing and very similar results, personally i just hate having to deal with making sure its insulated properly and taped securely. I just shove the probe down the thermowell and go have a beer

An example of the carboy cap