Fermentation chamber

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oro
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Re: Fermentation chamber

Post by oro »

fridges or freezers absorb heat they don't cool if that assists to picture whats taking place inside, so as wort temp increases the evaporator(coil inside fridge) absorbs the heat its giving off, the probe measures this change directly if the probe is in the wort or attached to the pail or carboy with an insulator, the fridge will continue to absorb the heat given off until the desired wort temp is reached, once reached 5-10 gallon of wort stays steady meaning the fridge will cycle far less. Air temp does not matter wort temp matters, air could be -20 or +120(exaggeration) who cares as long as wort is at your set point. Measuring air in this case is inefficient, may not be much but if controlling ferment temp, then measure the ferment temp.
Beer has food value, food has no beer value...

BottomsUp
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Re: Fermentation chamber

Post by BottomsUp »

oro wrote:fridges or freezers absorb heat they don't cool if that assists to picture whats taking place inside, so as wort temp increases the evaporator(coil inside fridge) absorbs the heat its giving off, the probe measures this change directly if the probe is in the wort or attached to the pail or carboy with an insulator, the fridge will continue to absorb the heat given off until the desired wort temp is reached, once reached 5-10 gallon of wort stays steady meaning the fridge will cycle far less. Air temp does not matter wort temp matters, air could be -20 or +120(exaggeration) who cares as long as wort is at your set point. Measuring air in this case is inefficient, may not be much but if controlling ferment temp, then measure the ferment temp.
Last say. Think of it deeply this way. The fridge/cooler will come on if the beer gets too warm. But no heat will come on if the beer gets too cold. It takes a lot of cold air over a relatively long time to cool liquids. So the freezer/fridge will stay on a long time to try to cool the beer, causing the temperature in the chamber to cool to very low temperatures. Thus the temperature of the beer continues to dip lower and lower after the desired beer temperature has been reached, because the chamber will still be exceptionally cool for a relatively long time. The beer will continue to adjust to this cold air until equilibrium has been reached, which will necessarily be below the desired temperature of the beer. Any other beers, etc. in the chamber could freeze as a result. Thus the fluctuation is on the cold side of the beer. It will dip much further below the desired temperature than above. Adjusting the air temperature through a small range of temperature difference assures a steady temperature of the beer with minor fluctuation. The air temperature might fluctuate a bit, but because of the slow change of temperature in the beer, its fluctuation will be minimal. Thus, unlike putting the probe directly in the beer, any minor fluctuation will be about the same above and below the desired temperature, resulting in a much better average.

oro
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Re: Fermentation chamber

Post by oro »

^ I do understand what your saying. I have 2 thermos in my fridge one measures wort, one air temp, the beer remains exact to the set point on the controller well the air does vary. If I was to put a hot wort into the fridge the air temp would dip very low, but the wort is at ferment temp when put in the fridge so maintaining it is easy the air may get to 60 degrees when running but thats about it.
Beer has food value, food has no beer value...

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bellybuster
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Re: Fermentation chamber

Post by bellybuster »

"Thus the temperature of the beer continues to dip lower and lower after the desired beer temperature has been reached, because the chamber will still be exceptionally cool for a relatively long time. "

this is where the STC1000+ excels, it also has an ambient probe so you can set the difference between beer and ambient. The total control is by the beer however.
And yes you are right. the chamber temp will go well below the beer temp, but.... the thermal mass of the beer will absorb/release much more energy than the ambient air in the chamber. 10 degrees cooler in the chamber might and that's a big might, mean .5 or maybe 1 degree in the beer due to thermal mass. Air has a very low thermal mass compared to beer. Water alone has mass more than 1000 times that of air.

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brhenrio
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Re: Fermentation chamber

Post by brhenrio »

bellybuster wrote:
this is where the STC1000+ excels, it also has an ambient probe so you can set the difference between beer and ambient. The total control is by the beer however.
And yes you are right. the chamber temp will go well below the beer temp, but.... the thermal mass of the beer will absorb/release much more energy than the ambient air in the chamber. 10 degrees cooler in the chamber might and that's a big might, mean .5 or maybe 1 degree in the beer due to thermal mass. Air has a very low thermal mass compared to beer. Water alone has mass more than 1000 times that of air.
Also the specific heat of water (the amount of energy needed to raise temp 1*C) is much higher for water than air. In cooling this specifically means that the beer will give off lots of energy to the air, while the air will change temp, but the beer will still have hardly changed temperature.
In the fermentor: Golden Sour, Not a Pill v2
Tap 1: Puck that Filsner; Berliner Weisse
Tap 2: Not a Pill; Lager
Tap 3: Paddockwood Kolsch
Tap 4:

BottomsUp
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Re: Fermentation chamber

Post by BottomsUp »

bellybuster wrote:"Thus the temperature of the beer continues to dip lower and lower after the desired beer temperature has been reached, because the chamber will still be exceptionally cool for a relatively long time. "

this is where the STC1000+ excels, it also has an ambient probe so you can set the difference between beer and ambient. The total control is by the beer however.
And yes you are right. the chamber temp will go well below the beer temp, but.... the thermal mass of the beer will absorb/release much more energy than the ambient air in the chamber. 10 degrees cooler in the chamber might and that's a big might, mean .5 or maybe 1 degree in the beer due to thermal mass. Air has a very low thermal mass compared to beer. Water alone has mass more than 1000 times that of air.
I use the STC1000 - I actually have three of them. Your argument about the mass of the beer applies exactly to my point. It is why the temperature stays stable while the air temperature fluctuates marginally.

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bellybuster
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Re: Fermentation chamber

Post by bellybuster »

have a read about Brewpi. They have done extensive research on this very topic

BottomsUp
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Re: Fermentation chamber

Post by BottomsUp »

bellybuster wrote:have a read about Brewpi. They have done extensive research on this very topic
I took a look and couldn't find anything substantial. Do you have a specific link I can look at?
Thanks.

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bellybuster
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Re: Fermentation chamber

Post by bellybuster »

any of the charts on the site show the ambient chamber temp fluctuations vs the beer temp being stable-ish.
I've been trying to find it but when brewpi was fairly new there was an experiment conducted between measuring the beer temp or the fridge air temp (ambient). The results showed that both ways effectively cool/warmed the beer within acceptable tolerances. That would be expected. The difference was the increased cycling and the much longer time it took to get to that acceptable temp when it was controlled by ambient temp.
A good way to look at it is if we put a 75 degree fermenter in a chamber and wish it to be 68 degrees and we control by ambient temp, the fridge will run until it hits set point of 68. Logical.
Once the chamber hits 68 and the fridge turns off the beer will start to release its heat energy to the cooler air. Being almost 1000 times greater thermal mass it will take a better of minutes for that chamber air to warm up and restart the fridge. The beer will have released a fraction of a degree. The cycle will continue over and over again until they reach equilibrium.
Now lets do the same with controlling by beer temp. Same 75 degree beer same 68 set point. The fridge will run continuously until the beer hits set point and shut down. The air in the chamber will be much colder than the beer so will in fact continue cooling it. Considering the difference in thermal mass, the beer will lose maybe a degree to the chamber. Fridge will not run again. At least not until the insulation qualities of the chamber show too much loss or the exothermic reaction of fermentation warms the beer above limit.
The big difference is by controlling the beer temp we are removing heat directly from the beer, not the air surrounding the beer. The temp of the air around the beer is now left to the mercy of the thermal mass of the beer which is much much greater.

I put my fermenters inside my chamber at just below boiling temp. My A/C unit runs solid for 10-12 hours then runs once maybe every 2 days. If I measured ambient instead it would turn off and on every 10 minutes for probably 3 days or more.
Cycling is what kills fridges/A/C units etc etc

This is a good discussion. I'm glad it hasn't gone south like it usually does on other forums. I am 100% open and willing to be shown I'm wrong.
Once I get my raspberry pi logger up and running I will do a real comparison in order to factually show I'm right or quite possibly wrong

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brhenrio
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Re: Fermentation chamber

Post by brhenrio »

The way you are explaining makes sense in my head belly. When I do my fermentation chamber build I will set up to measure beer temp directly if I can.
In the fermentor: Golden Sour, Not a Pill v2
Tap 1: Puck that Filsner; Berliner Weisse
Tap 2: Not a Pill; Lager
Tap 3: Paddockwood Kolsch
Tap 4:

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