Placement Of Temp Probe = An Anal Nerd's Findings

[juzz1981]

I dont have any temp sensor on my fermenter, i just shoot it with a IR gun

 

[felten]

You're right, yeast rehydrate better at higher temps, but higher temps aren't good for flavour development. That is why usually you are advised to rehydrate the yeast in hotter water before pitching into your beer.

Starting the beer off lower and then letting it ramp up towards the end is a lot better solution

I have the impression (can't remember whether I read it somewhere - hold on,
the Coopers kit instructions say to pitch at 26C) that pitching at temps a little
higher than the ferment temp is good to encourage yeast reproduction at the
start.

The J.Palmer How To Brew state anything more than 10F (5C) above the nominal
ferment range and fusels (bad alcohol) start to be produced too much and I think
21C is at the top of the nominal for Coopers' yeasts, hence 26C. I'm reckoning
that providing you can get the ferment temp down to the nominal value within a
day or so after pitching at a few degrees C above the nominal would be a good
balance between getting yeast to multiply rapidly at the start and then fermenting
at the right temp for the rest of the ferment.

T.

 

[Nick JD]

The Activator™ package contains a minimum of 100 billion cells in a yeast slurry.. The Activator™ is designed to directly inoculate 5 gallons of standard strength ale wort (1.034-1.060 SG) with professional pitching rates. For lagers, we recommend inoculating the wort at warm temperatures (68-70F/ 20-21C), waiting for signs of fermentation, and then adjusting to the desired temperature. Alternatively, for pitching into cold conditions (34-58F/ 1-14C) or higher gravity wort, we recommend increasing this pitching rate. This can be achieved by pitching additional Activator™ packages or by making a starter culture. Please see the Pitch Rate section for additional information. Instructions for the proper use of Activator™ packages:

1. To activate, locate and move inner packet to a corner. Place this area in palm of one hand and firmly smack package with the other hand to break inner nutrient packet. Confirm inner packet is broken.
2. Shake the package well to release the nutrients.
3. Allow package to incubate and swell for three hours or more at 70-75F (21-24C) or immediately direct pitch into wort.
4. Use sanitizing solution to sanitize the package before opening.
5. Shake well, open and pour Activator™ into five gallons of well-aerated or oxygenated wort at 70-75F (21-24C). Maintain temperature until fermentation is evident: by CO₂ bubble formation, bubbling airlock or foaming on top of wort.
6. Adjust to desired fermentation temperature.

21-24C wort temp folks (20-21C for a lager). Yeasties won't spit the dummy till they're multiplied up and shittin' alcohols. I always pitch my lager yeasts at 20C. Bring it down to the temperatures you get your best results from afterwards. Personally I think there's a fine line between happy yeast and rampant fusel/ester production with most yeasts. Finding this line is almost as important as freaking out about your anal probe.

 

[Silo Ted]

You're right, yeast rehydrate better at higher temps, but higher temps aren't good for flavour development.

Once again I agree with you felten. To extend on your comment, and for the benefit of newer brewers-higher temps might be good for yeast reproduction, but once it hits the wort a brewers main
interest is in making beer, not more yeast. For stepping up a yeast sample, room temp is fine with me. But when it comes to pitching its probably a good idea to have your starter at a similar temp to the receiving wort.

 

[gregs]

This is a good topic
An interesting point made regarding the fermentation temperature to aid yeast multiplication before lowering the temperature to the correct fermenting temp.

I wonder when fermenting larger volumes re 60 litres, how long will it take that batch size to drop from 21 degrees to the desired 11 degrees when using lager yeast. This would take some time I would presume, especially if placing the temp probe in the actual wort.

I have always for this reason pitched my yeast when the wort is at the recommended fermentation temp.

 

[razz]

Probably a good point with larger batches gregs, I'm doing 40 lt brews and I pitch at fermenting temps. Keeping the fermenter in a fridge, if I pitched at 18 and tried to take the fermenter to 12 degrees I would wait for approx 16-24 hours and the fridge may not like running non stop.

 

[big78sam]

Once again I agree with you felten. To extend on your comment, and for the benefit of newer brewers-higher temps might be good for yeast reproduction, but once it hits the wort a brewers main
interest is in making beer, not more yeast. For stepping up a yeast sample, room temp is fine with me. But when it comes to pitching its probably a good idea to have your starter at a similar temp to the receiving wort.

+1

A side point - A bit of forethought means the K&K brewer can fairly easily ensure the wort is at the desired temp so there's no need to cool down or warm up. I'm no maths/chemistry whiz but in my K&K days I used some basic maths to work out how much boiling water I should use to get the final wort temp about right.

For example, assume a final volume of 22 litres.
20 litres of water at 15 degrees (or whatever your tap water is assuming you're using this to top up)
2 litres water at 90 degrees (assuming it cools a bit)

I leave the tins and adjuncts out of the equation as I assume they are about room temp.

(20x15 + 2x90) / (20 + 2) = 21.8

21.8 degrees is about right. So I'd use 2 litres of boiling water when mixing tins etc up. You'll have to work out specifics yourself but it was just a rough rule of thumb that seemed to work for me.

http://www.scienceforums.net/topic/16788-c...er-temperature/ This is a better but brief explanation of how it works.

 

[Silo Ted]

Sam - that's a handy reference, and for those who need to change temps quickly its ideal. Those who are uncomfortable with using math formulae, but still want to think about forcing pitch temps and play around with mixing solutions for a desired temp (it works both ways) might like to bookmark this calculator.

http://www.onlineconversion.com/mixing_water.htm

Try it out with Sam's example, the results are the same.

Keep in mind that you might need to compensate your gravity predictions for the addition of plain water. For example, an initial 21L wort at 1.050 OG would drop to 1.046 after a 2L water addition. An extra 250g of dry malt (or sugar, or dex) would bring it back up.

 

[big78sam]

Sam - that's a handy reference, and for those who need to change temps quickly its ideal. Those who are uncomfortable with using math formulae, but still want to think about forcing pitch temps and play around with mixing solutions for a desired temp (it works both ways) might like to bookmark this calculator.

http://www.onlineconversion.com/mixing_water.htm

Try it out with Sam's example, the results are the same.

Keep in mind that you might need to compensate your gravity predictions for the addition of plain water. For example, an initial 21L wort at 1.050 OG would drop to 1.046 after a 2L water addition. An extra 250g of dry malt (or sugar, or dex) would bring it back up.

That's a much easier way of doing it. I think I'll bookmark that and use that instead of using a calculator or trying to do it in my head!

 

[Silo Ted]

Sorry to Michael if this is getting a bit off topic, but in a way its all tied in together with temperature control, and the best way to produce a pre-pitching temp.

Apologies out of the way, let's get seriously OT Sam, I wonder if the weight of wort per litre is significantly variable to the assumed weight/volume of water, enough to alter the mixing calculation by a couple of degrees? Your stated formulae, and the corresponding equal result from the online calc, are assuming the solutions to be water, not a sugary solution.

 

[michael_aussie]

Thankyou everyone .. some interesting thoughts.

For example, assume a final volume of 22 litres.
20 litres of water at 15 degrees (or whatever your tap water is assuming you're using this to top up)
2 litres water at 90 degrees (assuming it cools a bit)

I leave the tins and adjuncts out of the equation as I assume they are about room temp.

(20x15 + 2x90) / (20 + 2) = 21.8

21.8 degrees is about right. So I'd use 2 litres of boiling water when mixing tins etc up. You'll have to work out specifics yourself but it was just a rough rule of thumb that seemed to work for me.

ty again big78sam.
I'm going to be more scientific about my wort temp, but can't use just 2 litres of water; I always seem to need at least twice that to dissolve the solids.
I'm going to try adding some ice to counteract the extra heat I introduce with extra hot water.

Therefore SiloTeds link is even more useful as it also allows you to input ICE.
Thank you SiloTed ... I don't mind wandering topics ... it all adds to my knowledge. I always appreciate your input.

Sam - that's a handy reference, and for those who need to change temps quickly its ideal. Those who are uncomfortable with using math formulae, but still want to think about forcing pitch temps and play around with mixing solutions for a desired temp (it works both ways) might like to bookmark this calculator.

http://www.onlineconversion.com/mixing_water.htm

 

[michael_aussie]

http://www.onlineconversion.com/mixing_water.htm

Using Silo_Ted's link, I need 2 x 1.25PET bottles of ice in my wort.

 

[big78sam]

Using Silo_Ted's link, I need 2 x 1.25PET bottles of ice in my wort.

Not sure what you mean by that - how do you intend to use PET bottles? I assume just mean 2.5 litres of ice.

The other option is to use 4 litres of boiling water, add tins of goop, hops, LDME etc, and then cool this to around 40 or 50 degrees and finally add the rest tap water. It's much quicker and easier to cool 4 litres of near boiling liquid to around 50 than it is to cool 23 litres of wort. I'd do this by boiling water etc in a pot and then leaving the pot in a sink full of cold water.

 

[big78sam]

Apologies out of the way, let's get seriously OT Sam, I wonder if the weight of wort per litre is significantly variable to the assumed weight/volume of water, enough to alter the mixing calculation by a couple of degrees? Your stated formulae, and the corresponding equal result from the online calc, are assuming the solutions to be water, not a sugary solution.

I don't know about that. This was just a rough rule of thumb for me. The formula mentioned in the thread I posted talked about mass and specific heat capacity. I wouldn't have thought the sugar content would make much difference to mass. My understanding is the SG is in effect the ratio off the mass of a volume of liquid to pure water. In other words 1 litre of wort at 1.050 SG weighs 1050 grams or 5% heavier than 1 litre water, so we're not talking about enormous amounts of difference here. I have no idea about specific heat capacity though.

In any event, my non scientist mind figured that the sugar sourced from the tins, LDME etc could be excluded as the temperature is really determined by the water you're adding due to the much larger volumes of water. For example if you added the boiling water and the tap water and then end up with say 23 litres at 20 degrees and then added the extras the temp isn't going to change much. Common sense would tell me that the order in which you combine the ingredients shouldn't matter, i.e adding the boiling water to the tins etc, then adding tap water last should give the same result as combining the water first. I have no scientific basis for this.

 

[Silo Ted]

LOL you said what I was thinking. Does he cut the bottle off the ice ?

Michael, if youre getting into this solution mixing conversion concept, are you sure your tap water is 15 degrees? Not being in the same climate as you, but I just went and measured my tap water and it's 23 degrees. Also just checked my loungeroom Galileo Thermometer (imprecise functional art) and it's around 24 degrees.

This is a good sidestep discussion, and I reckon more people should be thinking about controlling their pre-pitching temps with mixing. To extend on Sam's last one, work out the least amount of boiling water you need to dissolve the LME, DME, whatever, and then dunk your saucepan into cold tap water. After about five minutes, drain the water, and do it again, leaving for 10 minutes. Then a third time for 15 minutes. Leave the lid on the whole time, apart from in between baths, where you might want to stir it with a spoon so get some currents going. You'll be surprised how much heat will dissipate, so when you tip the high SG solution into your fermenter, and top up with tap water, there's no 90 degree factor to push the overall readings up.

 

[Silo Ted]

I don't know about that. This was just a rough rule of thumb for me. The formula mentioned in the thread I posted talked about mass and specific heat capacity. I wouldn't have thought the sugar content would make much difference to mass.

Probably not enough to worry about, but I suspect there is a variance in weight between a volume of water and a volume of wort. It was more in the spirit of the discussion rather than for any practical application. Since posting that, I'm starting to wander off into heat dissipation variances of water vs wort. God help me, this hobby gets the old grey matter working

I have no scientific basis for this.

Off topic again (sorry Michael). A mate of mine came up with a funny statement about brewers, in that many have failed basic high school chemistry, but own hydrometers, refractometers, pH readers, build our own stir plate circuits to propagate micro-organisms, discuss water alkalinity profiles, have a range of thermos for various applications, work out attenuation figures, manipulate temperatures for ester production and all manner of other scientific applications.

 

[Ross]

Probably a good point with larger batches gregs, I'm doing 40 lt brews and I pitch at fermenting temps. Keeping the fermenter in a fridge, if I pitched at 18 and tried to take the fermenter to 12 degrees I would wait for approx 16-24 hours and the fridge may not like running non stop.

Razz,

Don't worry about over running your fridge, the fridge thermostat is not disconnected & will run as per normal, all that happens with your controller is that it turns the whole fridge off once fermentation temperature is reached.

cheers Ross

 

[piraterum]

i shove my probe into a piece of retired stubbie holder and tape it to the fermenter, it's just one of the old adflo analogue controllers btw

Dave

The idea of wrapping the temp probe with an insulator defies logic :blink:
This would effectively insulate the probe against temp change. You would have to wrap the whole fermenter in insulation the same as the probe, for this to be a viable option.

The most accurate way to measure the temp would to have a probe directly inserted into the wort. Preferably inserted between the the middle of the fermenter and the surface of the wort to account for the variation of temperature within the fermenter. The wort near the surface will be cooler than the wort in the middle. A quick google search can provide plenty of info on this:

Emerson Process management

Yokogawa proccess doc


Anyone have any pics of how they fitted a probe with a neat seal?

cheers,

piraterum

 

[Thirsty Boy]

You have misinterpreted the insulation of the probe method.

You put the probe directly onto the surface of the fermenter, and tape the insulation on so that its between the probe and the ambient air. Insulating it from the inside temperature of the fridge and making it read what is for all intents and purposes, the internal temperate of the wort.

The test have been done and described enough times over the years by various people, one of whom is me, that show the temperature measured via an immersed probe is usually not significantly different (ie less than one degree) to the temperature measured by an insulated, probe taped to the outside of the kettle.

 

[MarkBastard]

You have misinterpreted the insulation of the probe method.

I think he may be suggesting that insulating the probe in this way would mean that as the ambient gets colder than the liquid, the insulation will block that ambient cold air from hitting the wort behind where the probe is, and thus the probe will not be accurate.

I disagree and I think this is actually a positive benefit.

I imagine when you want your wort to be 18 degrees and the fridge gets the ambient air down to say 14 degrees, the edges of the wort get colder first, with the middle remaining warmer. With that in mind the area on the edge of the fermenter that is insulated may read a closer temperature to what the middle of the fermenter would be, so it's a good thing.

Either way this is all theory. In insulate using some leftover camping mat and I have zero cause to ever change this. It's just too easy.

My only concern is that my temp controller is only accurate to one degrees so the wort temperature itself needs to change a fair bit for the fridge to turn on.

Ideally the temp controller would have a greater accuracy but I'd use the same method.