Totally Baffled

[nicklawmusic]

During my last brew, I discovered some discrepancies between my liquid crystal thermometer (the type that sticks on the outside of your fermenting buckets) and my spirit thermometer.

So I ordered a Deluxe liquid crystal thermometer and also stuck that to my fermenting vessel in order to get a more accurate reading (the Deluxe BrewFirm thermometer goes up in units of 1°C).

I have just taken a hydrometer reading of my current batch. The two liquid crystal thermometers, which are stuck around a quarter of the way up the fermenting bucket from the bottom, are both giving the same reading of 19°C. My brew belt is about A third of the way down the fermenting bucket from the top. When I placed my spirit thermometer directly into my fermenting bucket, I got a reading of 26°C.

I am totally baffled! Does anyone have any ideas why there is such a discrepancy between the spirit thermometer and the two liquid crystal thermometers?

There are no flavours in the sample that I have just taken (it actually tastes really good) but I am wondering whether the liquid is warmer around the region of the brew belt, which is around the area in the beer where the thermometer is taking it's reading from, than at the bottom where the liquid crystal thermometers are.

Any ideas?!


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[flars]

Have you checked all your thermometers to see if they read the same? Cold and hot water can be used in the bucket when it is not full of wort.

Your spirit thermometer is probably sampling the warmer area of the brew belt. Warmth rises. The top of your wort will be warmer than the bottom since there is no active circulation.

If the brew belt were at the bottom of the bucket the warmed wort would rise mixing the entire wort in the process.

 

[nicklawmusic]

The last time I put my brew belt at the bottom of the FV, I totally nuked my beer and it got way too hot!


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[flars]

The last time I put my brew belt at the bottom of the FV, I totally nuked my beer and it got way too hot!


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Check out this thread. STC-1000+
You really need a temperature controller unless you are able to monitor and adjust the temp every two hours. This thread shows how to put together an inexpensive, but reliable, temperature controller. Temp control for both heating and cooling.

 

[Johnnyhitch1]

Crystal thermos (stick-ons) will give more of the ambient reading than interior.
Best bet for measuring FV temp would be to get a thermo well. Reading from the middle will give you the closest temp.

 

[sweetcell]

During my last brew, I discovered some discrepancies between my liquid crystal thermometer (the type that sticks on the outside of your fermenting buckets) and my spirit thermometer.

there's your problem: you're using plastic buckets. plastic is a poor conductor of heat (AKA it's a good insulator), so the temperature of the outside of the plastic isn't reflecting that of the beer inside.

those stick-on thermo-strips work best on glass carboys, which does a better job of transmitting the temp of the beer inside.

 

[Matt3989]

Toss the stick on thermometers... They don't even get close to accurate for the center of the brew. I guess they might be nice to keep you consistent, but if you really want to track temps, buy (or make) a thermowell that goes to the middle of the carboy then stick a probe in it.

http://morebeer.com/products/stopper-thermowell.html?gclid=CNXN49G4-b0CFS9p7AodaA0AOA

I also second the stc-1000, for less than 30 bucks your temp control will be way more accurate, not to mention easier.

 

[nicklawmusic]

I've just taken another temperature reading now I've had the brew belt off for a while and it's gone down 2c to 24c. The beer doesn't taste off though and I'm using Windsor dried yeast. Starting to wonder whether my spirit thermometer is a bit faulty? Can that happen? How can I tell?

 

[Setesh]

The stick on thermometers can give an accurate reading if you put some insulation over the top of them, but then you can't see them so it kind of defeats the point

A temp probe that you can tape to the side of the bucket and then insulate (a few of layers of small-bubble bubble wrap taped over the probe works well) is a much better option. A thermowell is the the best possible method, but a properly insulated probe taped to the side will get you within ~1 degree of the true temp.

 

[Matt3989]

You can check it in ice water and boiling water, since both will be pretty close to 0 and 100 respectively.

A lot of us on here swear by the thermapen, they're pricey, but they come in handy a lot more often than just brewing. Thermoworks makes other really nice digital thermometers for cheaper too.

 

[nicklawmusic]

What sort of probe would I need? Do you have a link?


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[Setesh]

What sort of probe would I need? Do you have a link?


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I would recommend an STC-1000 temperature controller which you can get here

That requires some wiring/electrical knowledge but it is a 2 stage temperature controller so you can use that to control the fridge the fermentor is in and the heater inside the fridge as well. It is by far the best route for the money IMO. If you are handy with code you can even doll up the STC-1000 into the STC-1000+. See this thread here

 

[Dan]

During my last brew, I discovered some discrepancies between my liquid crystal thermometer (the type that sticks on the outside of your fermenting buckets) and my spirit thermometer.

So I ordered a Deluxe liquid crystal thermometer and also stuck that to my fermenting vessel in order to get a more accurate reading (the Deluxe BrewFirm thermometer goes up in units of 1°C).

I have just taken a hydrometer reading of my current batch. The two liquid crystal thermometers, which are stuck around a quarter of the way up the fermenting bucket from the bottom, are both giving the same reading of 19°C. My brew belt is about A third of the way down the fermenting bucket from the top. When I placed my spirit thermometer directly into my fermenting bucket, I got a reading of 26°C.

I am totally baffled! Does anyone have any idea?

Any ideas?!


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Yes, I do. I'm going to use a bunch of letters sometimes overused on this forum.

Relax
dont worry
Have a
Homebrew

Or somrthing.




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[nicklawmusic]

Thanks Dan. The stout I made last when I first observed that this was a problem tastes pretty damn good, so I don't think the liquid crystal thermometers are too far out.

I think what is happening is that the warmer beer is sitting at the too of the FV, around where my brew belt is. The cooler beer has sunk to the bottom.

I guess maybe I need to conservatively heat my beer with a brew belt further down so the beer gets heated evenly.

I've looked into those thermostatic controllers before but I'm not that technical when it comes to wiring, etc.


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[Dan]

Thanks Dan. The stout I made last when I first observed that this was a problem tastes pretty damn good, so I don't think the liquid crystal thermometers are too far out.

I think what is happening is that the warmer beer is sitting at the too of the FV, around where my brew belt is. The cooler beer has sunk to the bottom.

I guess maybe I need to conservatively heat my beer with a brew belt further down so the beer gets heated evenly.

I've looked into those thermostatic controllers before but I'm not that technical when it comes to wiring, etc.


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[Dan]

Nick, sorry quoting you and then not typing anything after that. Having some difficulties with my phone. My apologies. Truly.

There are a few temp controllers on the market. Some are pretty cheap but do need a little DIY help.

Dont worry about that. Id be happy to help you build one. Im not all knowing, but wont give you advice that will end up burning your place down.

There is a wealth of very technical/ electrical savvy people here that will be glad to answer any questions you have about building a temp controller. You're among friends here. Ask away!


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[nicklawmusic]

Thanks Dan. I've seen these converted STC1000's but I don't exactly understand what their purpose is and how they control a brew belt. Are they not just used for cooling/heating a brew fridge?


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[RM-MN]

Thanks Dan. I've seen these converted STC1000's but I don't exactly understand what their purpose is and how they control a brew belt. Are they not just used for cooling/heating a brew fridge?


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The STC1000's are for controlling temperatures which can be derived from any electrical device. They tend to be used most often for controlling refrigeration because for most brewers, cooler fermentation temperatures than what are available in our houses are required but they aren't limited to that. The really are a thermostat with specific functions where they can control a higher voltage and current than a wall thermostat with more precision. Fastening the probe to the outside of the fermenter and insulating over it so it senses the contents of the fermenter rather than the air outside of it allows it to control the contents temperature by way of a refrigerator for cooling or a brew belt for warming (or any other heat source)

 

[nicklawmusic]

So is there a probe I can buy or a digital thermometer in which I can stick to the side of the fermentor and insulate, just to get a reading?

An secondly, if I insulated my liquid crystal thermometer with bubble wrap, would that give me a good reading of what is happening inside the FV?


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[GrogNerd]

I have the stick-on thermometers on my plastic buckets and have tested their accuracy with a probe thermometer inside at the same time

saw no discernable difference between the two readings. if there is a difference, it's well within my range of tolerance.

 

[nicklawmusic]

Thanks GrogNerd. I did a test with water (which I shall do again but with the brew belt after this batch I bottled) and the spirit thermometer and stick on one read the same.

I'm guessing that the warmer liquid in the FV has risen to the top, as the brew belt is near the top of the FV and cooler liquid has sunk, giving me the 19C reading on my stickies.

Not quite sure what impact the warmer liquid will have on my beer. It's hard to tell what volume of it is warmer as well as I can only stick my spirit thermometer in so far.

Has anyone experienced this before?


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[nicklawmusic]

I am 99% certain, after taking readings today, that what has happened with this batch is that the warm liquid has risen and cooler liquid is at the bottom of the FV.

I'm no science whizz but there is a continual rising and falling of the liquid as a result.

Does anyone know, then, how this effects a fermentation and the flavours? The top 20% of the beer in the FV may be too warm for the yeast at strain whilst the rest of it at an appropriate temperature.


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