controlling temperature with a temp regulator

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jrodie
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controlling temperature with a temp regulator

Post by jrodie » 2 years ago

I am writing to ask for advice/opinions on using a temperature controlled fermentation chamber. I have an old upright freezer and a Johnson thermostat, that I use to control the temperature. I have noticed that the wort is pretty resistant to changing temp as compared to the air in the chamber. If say I am attempting to maintain 62 degrees F on the thermometer attached to the fermenter, and the beer is currently showing 64 degrees F; I would need to drop the temperature of the chamber to 30 degrees F, in order to get the 2 degree F drop in a timely manner.

Does anyone think that would be bad practice (noticing the temp to be a couple of degrees high and drastically changing temperature to get it to change a couple of degrees, and then resetting the temperature of the chamber)?

Thanks
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Post by joshua » 2 years ago

I Think you have found that Yeast and Fermentation does have Heat.

Depending on the Mass of the Fermenting Wort/Beer, it may be possible to only keep the Fermenting 2F above the Freezer temperature.

You can drop the Freezers temperature 2F to Hold the Fermenter at 62F.

When you take the Beer down 2F, it will take Time, Maybe Hours, to cool the Fermenter, by Air.

If you have a Container that can hold the Fermenter, you could use Ice water to Chill the Fermenter to any temperature above freezing, Much More Quickly!!

JMHO YMMV.
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Post by jrodie » 2 years ago

Right... changing the fermentation chamber by only 2 F and expecting a change would take a long time, if at all, depending on how fast the fermenting wort was heating. I think you answered my question though when you suggested using ice water to bring the temp down. If it would be fine to do that, then setting the freezer all the way down to freezing, just for the time it takes to adjust the temperature, and then letting it heat up again (of course setting the temp a few degrees lower than it was before)should be fine.


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Post by Lylo » 2 years ago

2 methods I have used. Tape your probe to the vessel under some type up insulation, this way the controller is reacting more to the temperature of the beer rather than the ambient temp inside the chamber.
My best solution has been to use the 2 hole thermowell stoppers with the long stems into the beer.http://hopdawgs.ca/Equipment/Brewing-ga ... uct_id=271 this puts the probe right down into the beer and is much more accurate.
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Post by Rick » 2 years ago

What Lylo said.

I also have a Johnson controller, which will not fit in that thermowell. I simply stick the probe to the side of the fermenter with putty. Insulates it well enough so it's reading the beer temp, and not ambient air temp.


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Post by Lylo » 2 years ago

Rick one of mine is a Johnson as well. Don't be afraid to take a file or sandpaper to the probe,
and form it a bit until it first into the themowell. It is quite soft and malleable.
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Post by cwier60 » 2 years ago

Rick wrote:I also have a Johnson controller, which will not fit in that thermowell.
I'm not sure what the diameter of the Johnson probe is, but this one, which I use, has a 0.305" ID, which will fit many probes. I have seen different thermowells with different diameters, so there may be one that will fit the Johnson probe. It's hard to beat Brewers Hardware prices, $12 for the 16" or $20 for a 20" or 24" length.

Of course, attaching the probe to the side of the carboy is almost as accurate at tracking the beer temp (and eliminates an infection risk).
Last edited by cwier60 on 03 Jan 2015, 03:16, edited 1 time in total.

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Post by Rick » 2 years ago

Thanks fellas. I actually ferment in plastic buckets for the most part, so this is generally moot for me ... but I think I'll measure anyway just to see if I can grab something for my glass carboy.

I get super paranoid about temps with my Belgian Blond and Black IPA recipes, so having this setup might give me peace of mind in lieu of constant worry that my putty will fall off. It has happened a few times during non-critical times.


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Post by safebrew222 » 2 years ago

Rick and jrodie... I have a chest freezer and a STC-1000 temp controller. When I tape it to my fermenter I get a really good temp reading on the beer inside, but I overcool/heat my beer when I am controlling the compressor with the external thermostat as the beer will continue to cool/heat after the thermostat shuts down.

The solution I have came up with is that I assume the beer will be 2 to 4 degrees F warmer than the chamber temps during active fermentation. I cool my beer to 2 to 4 degrees below my fermentation temps, set my temp to that lower temp and pitch. The beer will warm up naturally. I don't connect the probe to the fermenter I leave it hanging in the air.

When fermentation dies down, or I need to increase the temp, I simply raise the thermostat accordingly. The beer takes 12 to 24 hours to catch up.

Of course, these readings are only as good as the thermometer or thermostat you are using... I use it as reference for comparison from batch to batch.

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Post by Lumpy5oh » 2 years ago

safebrew222 wrote:Rick and jrodie... I have a chest freezer and a STC-1000 temp controller. When I tape it to my fermenter I get a really good temp reading on the beer inside, but I overcool/heat my beer when I am controlling the compressor with the external thermostat as the beer will continue to cool/heat after the thermostat shuts down.

The solution I have came up with is that I assume the beer will be 2 to 4 degrees F warmer than the chamber temps during active fermentation. I cool my beer to 2 to 4 degrees below my fermentation temps, set my temp to that lower temp and pitch. The beer will warm up naturally. I don't connect the probe to the fermenter I leave it hanging in the air.

When fermentation dies down, or I need to increase the temp, I simply raise the thermostat accordingly. The beer takes 12 to 24 hours to catch up.

Of course, these readings are only as good as the thermometer or thermostat you are using... I use it as reference for comparison from batch to batch.
I have a similar set up and plan. The only difference for mine is that the probe sits in a bottle of water. The air in the chamber will warm or cool faster than water and may cause the controller to cycle more often.
Last edited by Lumpy5oh on 03 Jan 2015, 06:24, edited 1 time in total.
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Post by safebrew222 » 2 years ago

Yes lumpy. It does cycle more often during cooling. Good point.


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Post by cwier60 » 2 years ago

Lumpy5oh wrote:
safebrew222 wrote:Rick and jrodie... I have a chest freezer and a STC-1000 temp controller. When I tape it to my fermenter I get a really good temp reading on the beer inside, but I overcool/heat my beer when I am controlling the compressor with the external thermostat as the beer will continue to cool/heat after the thermostat shuts down.

The solution I have came up with is that I assume the beer will be 2 to 4 degrees F warmer than the chamber temps during active fermentation. I cool my beer to 2 to 4 degrees below my fermentation temps, set my temp to that lower temp and pitch. The beer will warm up naturally. I don't connect the probe to the fermenter I leave it hanging in the air.

When fermentation dies down, or I need to increase the temp, I simply raise the thermostat accordingly. The beer takes 12 to 24 hours to catch up.

Of course, these readings are only as good as the thermometer or thermostat you are using... I use it as reference for comparison from batch to batch.
I have a similar set up and plan. The only difference for mine is that the probe sits in a bottle of water. The air in the chamber will warm or cool faster than water and may cause the controller to cycle more often.
safebrew, I don't understand why you think you need to to account for a 2-4 deg offset. You say "When I tape it to my fermenter I get a really good temp reading on the beer inside"; therefore, you're measuring the temp of the beer. Why do you think you need to compensate? Jamil Z has reported several times on BN broadcasts that he and others have confirmed that a probe attached to a glass carboy and insulated can measure the temp of the beer to within 1 deg F. Let your controller do its job, but DON'T leave the probe hanging in the air. The STC1000 has a setting to account for short cycling, although that won't be an issue if you couple to the beer temp and its large thermal mass.

Lumpy5oh, the bottle of water adds some thermal mass to slow the temp changes, but it has no way to account for the temp rise in the beer from the fermentation. Even if you use a plastic bucket as a fermenter, you're MUCH better off taping the probe to the side of the bucket and adding some insulation on the outside. That will track the temp of the beer much better that monitoring a bottle of water.

Sorry, I don't have the time to find the link now, but look at the Brewing Network archives under probably Brew Strong for an episode on fermentation temp control.
Last edited by cwier60 on 03 Jan 2015, 08:53, edited 1 time in total.


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Post by safebrew222 » 2 years ago

cwier... I understand what you are talking about... consider the following... lets say you want to ferment at 19C... its hot and having the probe taped to the carboy, once the beer hits 20C the freezer starts. The freezer will run colder and colder until the beer hits 19 again and then shuts off. By that time, the freezer is much colder than that and will stay cold for a good while. So... what happens to the beer? It continues to cool off. Sometimes as much as 2 or 3 degrees C before leveling out and warming up. I want to ferment at 19C and not an oscillating temp between 16 and 20. This is why I have taken off the temp probe during active fermentation. I can get much stabler temps during the crucial 4 to 7 days of active fermentation.

I hope I make sense. Its the best way I know how to sum up my experience and thinking.


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Post by jrodie » 2 years ago

I have always left the temp probe off the fermenter for the reason safebrew just talked about. You can let the air temp vary by several degrees and the wort will maintain a more stable temp because it is more resistant to temp changes than the air around it. I do find that during active ferment I have to check on it regularly to compensate for increased heat until I find the "the sweet spot". I sometimes use some pretty wild temp swings on my controller in an attempt to maintain a specific heat, but I suppose as long as the temperature of the wort is only changing by a couple of degrees that's OK. Feel free to correct me if I'm wrong about that last statement :)


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Post by cwier60 » 2 years ago

safebrew222 wrote:cwier... I understand what you are talking about... consider the following... lets say you want to ferment at 19C... its hot and having the probe taped to the carboy, once the beer hits 20C the freezer starts. The freezer will run colder and colder until the beer hits 19 again and then shuts off. By that time, the freezer is much colder than that and will stay cold for a good while. So... what happens to the beer? It continues to cool off. Sometimes as much as 2 or 3 degrees C before leveling out and warming up. I want to ferment at 19C and not an oscillating temp between 16 and 20.
I understand your thinking exactly, and I'll have to say that I don't yet have the ability to track the real-time temperature of my beer, so I don't have the data for the temp hysteresis that my beer "sees". However, the hysteresis for the STC1000 can be set as low as 0.3°C. Then if you can set the temperature control for your fridge/freezer higher so that it doesn't cool as much when it's on, you may be able to reduce that 2-3°C swing to maybe 1°C.
jrodie wrote:I suppose as long as the temperature of the wort is only changing by a couple of degrees that's OK. Feel free to correct me if I'm wrong about that last statement :)
I think you would like to be able to maintain the temp to a few degrees swing. Beyond several °C, the yeast may actually experience problems as the temp swings to the low end, stalling if the temp backs off too much.

I'd suggest those interested in more advanced temp control to look into the STC1000+ (on homebrewtalk.com) and BrewPi, which is a Raspberry Pi based controller that I'm getting ready to move to as soon as I get the geek time to work on.
Last edited by cwier60 on 03 Jan 2015, 11:31, edited 1 time in total.


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Post by cwier60 » 2 years ago

Here are a few links on the BrewPi and HOWTO - Make a BrewPi Fermentation Controller For Cheap and the STC1000+. The HBT threads are quite extensive.
Last edited by cwier60 on 04 Jan 2015, 00:41, edited 1 time in total.


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Post by safebrew222 » 2 years ago

Thanks cweir... I have seen both of those links before. They are great resources. Maybe I have a different model of the controller. I can only go by 1C increments... I could have sworn I ordered the right one. Its been 2 years already. Maybe a new controller build is in order.


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Post by PistolPatch » 2 years ago

Lots of great answers and thinking above. It's not an easy area for reasons you have already outlined above. Here's what I do but a few things first...

1. We are all lucky enough to have a fridge and temp controller. Many brewers do not and produce good/great beer.
2. There could actually be advantages that have not yet been researched in having a wort (just like a mash) fluctuate by a few degrees up and down during fermentation.

In other words, perfect temperature control should not necessarily be an important goal.

...

In fact, I don't think I'll say what I do yet because maybe the above is worth pondering first?

:think:
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