Ambient temps versus actual fermenting temps

I have read and I am sure you all have read that the actual temperature of the fermenting wort can get several degrees higher than the ambient temps. I figured 4-5 degrees....I have my ferment room temperature set at 60 degrees, and it is temp controlled doesn't vary by more than a couple of degrees. I tried attaching the probe directly to the carboy but the heater side would not work properly that way due to a safety shut off on the heater kicking in before it could raise the temperature of 5 gallons of beer a couple of degrees...SOO I have to just control the ambient temps.

I was having some issues so I posted on here asking for a solution and a very helpful poster sent me a PM telling me he uses wireless indoor outdoor thermometers on his fermentors. he controls the temperature of the room, but MONITORS his fermenting vessels individually and adjusts the ambient to get them right. Anyway I went to Menards today and bought a wireless thermometer. I attached it to my carboy that the kraussen had already started falling on and in my 60 degree room it was over 71 degrees. An 11 degree difference!!! Keep in mind this was AFTER the most vigorous fermentation was over. My beers have been good but there are some slight off flavors and I think maybe this is the issue.

I brewed again tonight and attached the sensor to the new carboy. I am setting in my house.. the carboy is in my shed and I can tell you the actual temp of the beer is 64.8 degrees. This thing has alarms to tell you if the temp gets too low or too high. and you can buy up to 3 more sensors that it will monitor individually. Best of all it was under 20 bucks!

So for the new brewers out there, when you are told to keep ferment temperatures down, try to monitor the actual temperature of the fermenting beer and NOT The ambient temperature. Like I said in my case there was an 11 degree difference... I know it is harder but you will make better beer for doing so.

Wireless...that's cool. Next you'll get an Arduino and have it adjust your thermostat based on the wireless temp
I use a temp probe in a thermowell suspended in my carboy to monitor the ferm temp (it's connected to an STC-1000 that drives a FermWrap). It is really nice to get good ferm temp control....eliminates a huge variable.

So where can I buy this bad boy? What brand, model number? Is it online somewhere?

This I getting me excited. I need a good thermometer.

I bought it at menards.. it is a SPRINGFIELD PRECISETEMP....... However it may not be as great as I thought.. absolutely zero activity this morning in the airlock..no kraussen nothing. I pitched a starter at about 1AM and usually by this time the airlock is rapid firing. the ambient is seat at 55 degrees and the ensor is reading 64 degrees... I do not believe there is any way that is correct with no activity....oh well time will tell.

Once again I prove that patience is not one of my virtues. I went out just now and there is a nice kraussen but the airlock was silent. removed the airlock and reinstalled it and "blurp blurp blurp" right away...musta been plugged somehow. The reading on the remote sensor now says 65.3 degrees so it is slowly raising like it is supposed to....oh yeah I did raise the ambient 2 degrees.

This is pretty cool...just walked in the kitchen and checked the temp of my beer that is out in the brew shed....66.7 degrees so it is probably at high kraussen right now. that is 11.7 degrees above ambient temp......I may even take it a touch further. there is a probe that you can purchase for the remote sensor that I THINK is waterproof.. I may drop a probe right into the wort.

I've been wanting to put a thermowell with a probe in my carboy and one submerged in a swamp cooler and track ambient T vs. fermentation T over time, i think it'd be a pretty cool experiment, especially if you can get a graph for a few of different yeast strains.

I'd use a swamp cooler so i could get a more accurate idea of the energy released by the yeast, I'd imagine you can relate that to o2 needed and all kinds of other factors.

There's a post of mine in the DIY forum where someone responded with a way to build a cheap wireless temp monitor that you can check over the internet. (I'd post the link but I'm on my phone right now)

I am setting at 67.6 degrees right now and the ambient is set at 55... I would have never believed there was that much difference. Keep in mind the sensor is taped to the side of the carboy covered with a folded up towel so I would guess the actual BEER temp is a degree higher. I would bet that the beer is MUCH cleaner tasting than what I have been making . I was setting the ambiemt at 60 thinking 4-5 degrees difference. This is a german ale/kolsch yeast. brewing one of Biermunchers recipes and he recommends 68 degree ferment temp so I am real close. I wish I had a way to adjust my ambient from in here. THAT would be really cool. I will have to check into the computer stuff.

Steve,
Sounds like you are headed to Automation at full speed. You would be able to monitor and control your ambient if you used an Arduino, Picaxe, PICMicro or any other chip from many different manufacturers. In theory you could set your temp or back an adjustment even over a smart phone too. The new Rasberry Pi appears to lend itself well ,as well as the previously mentioned stand by's. Welcome to the "Automation Adiction" , I am eaten up with it and it's pretty fun so far. I can sit in my wheelchair and see what my brew is doing over 100 feet away. Sure saves 4 wheelin in my WC to get to my shop... Don't be afraid to try different ideas, you might hit on the next hot gadget and make a million bucks, ya never know....
Bob

I wish I had the tech savvy to build something like what you are talking about. A gadget that will monitor the temp and send an alert to my cell and allow me to adjust the temp from anywhere I have cell coverage. My technical abilities end at plugging something into an outlet lol.

One thing that can help with this is to try to couple the temperature of the fermenter as tightly as you can to the thermometer that's driving the thermostat. I usually ferment in a refrigerator, with a wired thermometer probe taped to the side of my Better Bottle and a thermometer strip near the bottom. From my observation, I believe the strip thermometer reflects predominantly the beer temperature, while the thermometer probe is heavily influenced by the air temperature.

What I find is that, when the refrigerator is going, the beer temperature can be 15 to 20 degrees higher than the ambient, and can hold this for a long time. This is simply because there's a whole lot more thermal mass in the beer than in the air in the fridge. Once the compressor cycles off, the ambient very quickly equilibrates with the fermenter and the two temperatures match. So in this case, there's no need to worry about the difference. The "ambient" is small enough that it's dominated by the fermenter. If I ran the compressor based on the beer temperature, it would probably save some on/off cycles, but that's about it.

If you're in a room, though, the fermenter makes almost no difference to the room temperature. It may raise the temperatures in its immediate vicinity, but it's going to take a long time for that to propagate out. As a result, the thermostat won't react to the fermenter temperature, as you've observed.

So, IMO, the most effective thing to do is to restrict the volume you're trying to heat/cool so that you can tie it very tightly to the temperature you're trying to control. Turning the room down to 50°F because you're trying to cool a 5 gallon fermenter is a bit wasteful...

A thermowell attached to your stopper is really the best way, it gives a very accurate temp of the middle of the beer, i find those stick on strips to be a pretty terrible indicator typically

In my fermenter fridge I run a computer fan blowing at the carboy to improve heat transfer from the beer to the air. It's an easy way to keep things (more) equal. Plus keeping the fridge full of other things with mass (I store my Corny's full of sanitizer in there) so it doesn't cycle as often to cool the air. It's amazing how much insulation you can get from stationary air.

Yet another reason why I use a ghetto water bath.

I can take the temp of the water and know it's almost the same as the fermenting beer. Water temp doesn't fluctuate nearly as much as air temp and is easily adjusted with frozen water bottles or swapping out some of the water with hot water.

I have an actual room I built to ferment in. I have an ebay temp controller hooked to a heater and an AC. The AC side works perfectly if I attach the probe to the side of the carboy. I removed the front cover of the AC and pulled the thermistor wire out and put it into a tube with a light bulb in the other end. The controller turns on the bulb and the AC that way the sensor on the AC is fooled by the heat of the bulb and it will run down lower...how low I have no idea as I have had no need to test it yet.... However the heater side shuts off trying to raise the thermal mass of the beer. There is a safety switch I do not know how to bypass that will not allow it to run long enouigh to drop the temp low enough. My solution was to just hang the probe in the air. It works to keep the ambient at whatever temp i want it at. I set the ambient at 60 thinking a 4-5 degree difference would be about it.. this has shown me that there is a big difference in the ferment temp compared to ambient temp. This is good enough for me for now but like I said it would be pretty cool to be able to adjust temps remotely....

http://www.gottabemobile.com/2011/08/03/cheaply-control-your-thermostat-with-a-smartphone/

gotta be a way to make something like this work

Probably possible. Though I think you'd be better off properly closing your control loop so that you can just set the temperature you want and trust the system to keep you there.

i have no idea what that even means...see told ya I was dumb

Sorry... The control "loop" here is the connection (however it's made) between the heater/cooler and the temperature of the beer that you're trying to control. It's a loop in the sense that you (somehow) measure the temperature of the beer, then apply heat or cooling, which then changes the temperature of the beer, which you measure, and react.

Currently, you have what I'd call a loose loop---you are not directly measuring what you are trying to control, so your system can't regulate the temperature very effectively. It sounds to me like you are trying to compensate for this by "inserting yourself" into that loop. There's not anything wrong with that. It's often easier to put a human in the loop than to develop a robust automatic solution. I actually do it with my refrigerator for fermentation. In my case, I set an outlet timer to turn the fridge on and off the right amount to keep the temperature where I want it. It sounds like your system is already more sophisticated than mine!

The downside is that it's a lot of work and, in the end, isn't very precise anyway. Thus, if I were in your shoes, I would try to fix it the "right" way. When I say "tighten the control loop," I mean I think you should sort out your heater issue so that you can stick your thermometer right on the beer and directly monitor the temperature you're trying to regulate.

I wouldn't really advocate overriding the safety on your heater, that might be there for a reason... But you could, in principle, find a way to limit how long it is asked to run in one go. If the beer hasn't reached the temperature target, switch off for a short time, then turn it back on. This isn't necessarily an easy thing to rig up, though. But it's just an idea.

Thanks zeg...I understand now. yes I had it set up just like you are saying but the heater is an issue. I may need to invest in a bigger heater or find someone versed enough in electronics to by pass the safety switch safely.. I thought about a ferm wrap but right now I have 6-7 brews in there in different stages of fermentation. I usually monitor the newest brew that will be the most active. I may make a thermowell that goes down in the bung and drop the probe in that and see if that is any better.. thanks for the tips.

Here in Hawai`i I never have to worry about heating my fermenting beer. Just keeping it cool and so I have a freezer, top loading. I'll have to play w/the air temp and the liquid temp to see the differences, but you guys w/refridgerators, remember every time you open the door all that cool air flows out the bottom and is replaced by the air outside. At least in a chest freezer you don't let all your cold air out when lifting the top.

looked at the temp guage just now...beer is at 57 degrees....went out to chec and the damned heater has quit again.

I cannot get this heater to come on.. hooked up a different one and it is running I don't get why tis keeps happening. the room is the size of a small closet and very well insulated. a small electric heater can run you out of it but this is the second one to just quit. I cannot get this one to come back on at all.

What's the air temperature when it's shutting off? Does the heater have a thermostat? Just guessing, but it's possible the air temperature rises quickly, trips the thermostat, and shuts off the heater. If that's the case, the air temperature should drop while the fermenter temperature rises. Eventually the air will drop below the thermostat point and the heater should come back on. This should be fine, eventually you'll reach equilibrium where air temperature = beer temperature (ignoring any heating the yeast are doing to the beer).

But that's just a guess. Do the heaters come on if you take them out into a larger, cooler room?

zeg said:

What's the air temperature when it's shutting off? Does the heater have a thermostat? Just guessing, but it's possible the air temperature rises quickly, trips the thermostat, and shuts off the heater. If that's the case, the air temperature should drop while the fermenter temperature rises. Eventually the air will drop below the thermostat point and the heater should come back on. This should be fine, eventually you'll reach equilibrium where air temperature = beer temperature (ignoring any heating the yeast are doing to the beer).

But that's just a guess. Do the heaters come on if you take them out into a larger, cooler room?

Click to expand...

nope.. the one I took out this morning I set outside hooked to an extention cord and it took 2 hours before I could turn it back on ( may have been faster but I didn't continually try) i moved the heater to the floor rather than on a shelf I had built and it seems to be working better BUT The outside temp has risen a LOT so it isn't having to work often. I bought another remote sensor and am monitoring ambient and the beer temp from in here now....not sure that anything is working properly now........