Is fermenting exothermic

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Is fermenting exothermic

Postby EvansTheSteam » Fri Sep 26, 2014 14:04

Having read many posts that a ferment gives out heat, I thought I'd give it a casual study.
I did a brew on Wednesday, a bog standard bitter, and put in my fermenting fridge.
Once it had stabilised at 19C I noted how often the heater came on to keep the brew at temperature, it was about once every 5 hours for the 0.5C drop.
Since the ferment has started, about 17 hours ago, it has not yet reached the temperature where the heater switches on.
It has been losing heat at a very very slow rate and the garage temperature has been fairly constant.
So my conclusion is yes, it does produce heat, but in small quantities.
I suggest you ignore the ramblings of an old man.

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Re: Is fermenting exothermic

Postby Aleman » Fri Sep 26, 2014 14:07

I've actually seen +5C above ambient when a fermentation is really going for it ;) (*)

Lots of yeast, Insulated Fermenter, Big Beer = Exothermic Fermentation :thumb:

Which is bad news if its 22C at ambient :(

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Re: Is fermenting exothermic

Postby GrowlingDog » Fri Sep 26, 2014 14:14

I've heard this before but never really noticed it myself as I've always left my fermenters tucked up in fridges controlled by an STC 1000 and never watched them closely.

Well at the moment my STC-1000 has broken so I have no automated temp control, so it is a case of me checking the temp regularly to ensure all is good,

The fridges are in my garage and it's quite cool in there at the moment, but I've not needed to turn the heater on for a few days while fermentation has been active, so it must be generating heat.
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Re: Is fermenting exothermic

Postby EvansTheSteam » Fri Sep 26, 2014 14:31

Aleman wrote:I've actually seen +5C above ambient when a fermentation is really going for it

It's only 23 litres with 11g of yeast.

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Re: Is fermenting exothermic

Postby Bluezephyr » Fri Sep 26, 2014 15:11

For the first few days of a new brew I've only ever seen my STC switch on the fridge, temp goes up again and it comes on again. In the winter time when room temperatures are lower ill check again.
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Re: Is fermenting exothermic

Postby Ciderhead » Fri Sep 26, 2014 16:07

I use a brewpi in an A rated fermenting fridge with a 60W conservatory heater and fan, it uses a thermowell through the cork in the top of my carboy. In full flow it controls the temp of the ferment +/- 0.05 of a degree which is even better than the accuracy of the probe itself!
I measured 2 brews before I connected it all up to start and on Nottingham there was a 2.5 degree increase on an 05 there was 3 degrees but it was a higher abv.
I guess its dependant on what ambient is, amount of fermentables, size of pitch, O2 present etc but its definitely happens.

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Re: Is fermenting exothermic

Postby AltonAnt » Fri Sep 26, 2014 17:52

I can't have two ferments going in my fridge at different stages as the one in the rigorous stage will run away if it isn't the one being measured.
I have an STC-1000 controlling the fridge but measure each FV with a DS18B20 so know fairly accurately what is going on.
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Re: Is fermenting exothermic

Postby EvansTheSteam » Fri Sep 26, 2014 21:31

Oops, it's gone up to 19.3C and tripped the chiller in!
Maybe a bit more heat is generated than I gave credit for.

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Re: Is fermenting exothermic

Postby Brewtrog » Wed Oct 08, 2014 22:23

It makes sense that brewing would be exothermic - it's respiration of yeast after all, and, as far as I'm aware, all respiration is exothermic (though don't quote me on that, there's probably something out there that's there to prove the rule)
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Re: Is fermenting exothermic

Postby BeerBloke » Thu Oct 09, 2014 09:30

Yes fermentation is exothermic. On our homebrew scale it's not so obvious as most FV's aren't insulated so the heat is lost. On our commercial kit the FV's are insulated and we use a chiller to keep the temperature down to what we want. It's very rare we have to try an heat one up thankfully!!

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Re: Is fermenting exothermic

Postby Gorty » Fri Oct 31, 2014 12:28

I remember reading that if you are using the 'Turbo' yeasts your biggest problem is likely to be keeping the temperature down low enough so the yeast is not overheated and deadified!

Buy wisely, brew carefully, drink copiously and stuff the rest!

Fermenting:

25L The Range 'MYO' Red.
25L The Range 'MYO' White.
5L 'WOW' Pineapple.
5L 'WOW' Blueberry.
5L 'WOW' Pomegranate.
5L 'WOW' Mango.

Clearing:

25L The Range 'MYO' White.
25L The Range 'MYO' Red.
5L 'WOW' Orange 2nd attempt.
5L 'WOW' Ribena.

Bottled:

5L 'WOW' First attempt.
5L 'WOW' Cranberry.
5L 'WOW' Apple.
5L 'WOW' Pomegranate.

Drinking:

25L The Range 'MYO' white.
25L The Range 'MYO' Red.
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Re: Is fermenting exothermic

Postby divingdavey » Fri Dec 05, 2014 11:58

I've got myself a fridge on ebay for 99p and ordered an STC-1000 so am going to rig myself a fermenting fridge up asap... What's the optimum temperature to set it at for wine?
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Re: Is fermenting exothermic

Postby Aleman » Fri Dec 05, 2014 12:55

I normally go for 18C for Whites and 22-25C for reds

please note:The use of punctuation, bold, underlining, italics, and different sized type, follows the convention used in writing, for many years, to place emphasis on the point being made, and to highlight the importance of that point in the opinion of the author. It is not the intention of the author to shout, if that was the case the author would adopt the, much more recent, convention of using all capital letters.
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Re: Is fermenting exothermic

Postby divingdavey » Sat Dec 06, 2014 09:48

Thanks Aleman. What do you do with the temperature sensor, tape it to the FV or just leave it hanging in the fridge?
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