Measuring fermentation temperature

[mobydick]

This is my first brew and so I'm trying to ensure everything is just right.

I have one of those stick-on strip thermometers on the side of my fermenting barrel, but its seems to show bugger all - as in it's difficult to read.

My brew fermentation had slowed considerably after just 3 days. I measured the temp of the wort by removing the lid and measuring with a digital thermometer - just 17C. I have tonight turned on the immersion heater and its started going again. I don't want to keep opening up the barrel to measure the wort temp with a digital thermometer so I'm trying to think of a better way.

I also have a digital thermometer with a two different temp probes courtesy of my beautiful wife who is a food safety auditor. Using the flexible temp probe I am able to insert it into the air lock past the water, into the top of the u bend. I am basically measuring the temp of the gas coming out of the air-lock before it passes through the sterilizer fluid. The gas flow is strong. It had stopped bubbling as the temp had dropped to 17C, it has now picked up again. The temp of the gas in the airlock measures 18.7 degrees at the moment.

What are your thoughts on measuring the temp of the gas as being an indicator of the wort temp?

[Pale_Ale]

Not sure on the gas as a measurement, but I would think a better and easier way of doing it would be to do what I do with my FridgeMate probe, which is to stick it to the side of the fermenter where there is wort and insulate any part of the probe exposed to air and not the fermenter with blu-tak. There's only a couple of mm worth of plastic separating the probe and the drink.

[wambesi]

I second that. I have mine taped to the side of the fermentor with some wetsuit material then taped over, it has a very accurate reading.

I also use the stick on ones, not the best but I have not had a drama as long as they are positioned properly.

[Dogger Dan]

I think we are worrying to much. You are trying to warm up/cool down 23 litres of liquid. I have found that the biggest issue is temp stability rather than actual temp. try to avoid big fluctuations. At this time if you are brewing at 18 deg C or 26 deg C you wont notice huge differences taste wise between the beer (assuming you are using Coopers ALe Yeast). You will notice some huge changes if you fluctuate between 18 and 26 though

Dogger

[Pale_Ale]

At this time if you are brewing at 18 deg C or 26 deg C you wont notice huge differences taste wise between the beer (assuming you are using Coopers ALe Yeast).

What ? Are you saying that a brew using Coopers yeast will taste similar whether brewed at 18 or 26? Because if so I have several shithouse batches brewwed at 26 to contest that theory!

[mobydick]

It's actually Safale US-05 that I'm using in this brew. My fermentation had slowed to almost stopping, but I couldn't really tell what the temp was as the strip thermometer is pretty useless (maybe its a dodgy one).

I don't want to have to keep opening the fermenter to take the temp, so I was hoping that measuring the temp of the gas might be a go'er.

But I will do as you guys suggest and tape/blue tack the probe to the side of the tank.

[ryan]

At this time if you are brewing at 18 deg C or 26 deg C you wont notice huge differences taste wise between the beer (assuming you are using Coopers ALe Yeast).

What ? Are you saying that a brew using Coopers yeast will taste similar whether brewed at 18 or 26? Because if so I have several shithouse batches brewwed at 26 to contest that theory!

That`s right- Coopers yeast brewed at 26* is not a good taste. But I`m intrigued why you did several of them?

[lethaldog]

At this time if you are brewing at 18 deg C or 26 deg C you wont notice huge differences taste wise between the beer (assuming you are using Coopers ALe Yeast).

What ? Are you saying that a brew using Coopers yeast will taste similar whether brewed at 18 or 26? Because if so I have several shithouse batches brewwed at 26 to contest that theory!

If you actually look at what the man is saying it is true for the most part, beer brewed at either temp will be a nice beer but fluctuating between temps, no matter what the temps are is not good, possibly look at your brews that were brewed at 26*C and ask yourself if they were at a constant 26*C

[ryan]

Beer brewed at a constant 26* with a Coopers yeast won`t be a good beer.

[Dogger Dan]

Before any one gets to carried away I thought that the upper limit for Coopers Yeast to be brewed is 30 degrees. Am I wrong with that? If I am sorry.

The point I was trying to make is you can brew at the limits of the yeast either cold or hot and not get the off tastes that come from the protein coat as the yeast goes into dormancy. If you fluctuate your temps wildly through the spectrum you will get those tastes.

So back to my point I was trying to raise here, don't be to concerned about the actual temp, just keep it constant in the range



Dogger

[Dogger Dan]

Before any one gets to carried away I thought that the upper limit for Coopers Yeast to be brewed is 30 degrees. Am I wrong with that? If I am sorry.

The point I was trying to make is you can brew at the limits of the yeast either cold or hot and not get the off tastes that come from the protein coat as the yeast goes into dormancy. If you fluctuate your temps wildly through the spectrum you will get those tastes.

So back to my point I was trying to raise here, don't be to concerned about the actual temp right now, just keep it constant in the range


Dogger

[Pale_Ale]

Hi Dogger,

Don't worry, no ones getting carries away


The upper limit of Coopers dried yeast is 30C, probably more, but I would'nt recommend brewing it above say 22. The esters produced at 26 or higher are unbearable.

But I definately agree with your final conclusion which is that variation is more detrimental to the beer than a constant temp, even a constant higher temp.

[Dogger Dan]

Thanks Pale Ale,

Actually the upper limit is 28 deg C, or 80 deg F

You can still brew there, really.

Dogger

[shane_vor]

To answer the first question, the temperature of the gas will vary more rapidly than that of the liquid. Is it possible to immerse your flexible temp probe? I did read correctly that you've run it through your air lock???

[Pale_Ale]

Thanks Pale Ale,

Actually the upper limit is 28 deg C, or 80 deg F

You can still brew there, really.

Dogger

Sorry, the quoted upper limit is 28C but it is a very tolerant yeast and will ferment at 30C or higher without alot of problems (besides the taste)

[mobydick]

You read right. I ran the probe through my air-lock. I have two probes connections. (This thermometer is for pro kitchen applications btw - food safety). One probe is long and skinny like a skewer. The other probe is just a flexible piece of wire that measures ambient temperature. Typically you would place this flexible probe inside a refrigerator to measure the air temp when the door is closed.

Anyway it isn't quite flexible enough for me to jiggle it right through the s bends of the air-lock. Might sit down and try again - patiently.

I've noticed though that with it placed in the air-lock, just placing my fingers on the air-lock causes the temp to rise, so I think it is not showing an accurate temp inside the fermenter. I need to get it immersed in the brew.

[Pale_Ale]

....or on the outside of the fermenter...it is accurate enough for most home brewing activities...