# Are 'stick On' Plastic Strip Thermometers Fairly Accurate?



## Bribie G (2/7/08)

Recently returned to HB after a 15 year absence and now using some of the tech. that wasn't around in those days. I have a plastic strip thermo on one of the fermenters and wonder how accurate or reliable they are? So far in SEQ the winter weather has been quite mild and my thermo on a fermenter in the garage, which gets all day sun on one (brick) wall has been showing 18-20 in the morning, climbing to 20-22 by late afternoon.

Suits me fine as I'm just brewing session kit + additive beers and not into strict lagering methods.

Are the $3 strips fairly reliable?


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## blackbock (2/7/08)

I've found them OK as long as you don't zap them with boiling water, or think that what you are measuring on the outside of the fermenter is the actual temperature of the wort.


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## EK (2/7/08)

blackbock said:


> I've found them OK as long as you don't zap them with boiling water, or think that what you are measuring on the outside of the fermenter is the actual temperature of the wort.



While it may not be the actual temperature of the wort, I don't imagine it to be too far off, the plastic of the fermenter should be within an acceptable margin of error compared to the wort.

EK


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## kabooby (2/7/08)

I think they're pretty accurate. Give or take 5 degress :unsure: 

Kabooby :icon_cheers:


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## Brewer_010 (2/7/08)

I use mine mainly as an indicator of fermenter contents temperature, with a digital thermometer also measuring the air space (close by). My brewing box is nice and stable temperature-wise.

In my observations, the airspace is generally a degree lower than the strip, so as long as I keep the airspace to 16-18 for ales I'm happy, and 8-10 for lagers. Haven't gone to the botheration of plugging a sensor into the wort cos I couldn't beef hooked. 

It is homebrewing after all  .


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## Thirsty Boy (2/7/08)

mine generally reads just about the same temperature as the thermocouple I have attached to the outside of my fermentor - and after several experiments comparing temp readings from a sensor in a thermowell in the wort; and the sensor attached to the outside, they are effectively the same thing.

So I say that the strips are (within a reasonable margin of error) giving you a pretty good description of the temperature of your wort.


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## browndog (2/7/08)

I put down a brew last friday and noted that the strip thermometer was showing 20C from the plate chiller, when I put the fermenter into the fermenting fridge with associated fridgemate thermocouple the fridgemate showed 19C. I was suitably impressed.

cheers

Browndog


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## braufrau (2/7/08)

My strip reads about 2deg above the thermocouple, which I've checked against another thermometer. I think I cooked the strip cleaning with hot water too many times 
Good to know the T on the wall of the fermenter is close to the inside T.

BTW - where do you get them for $3. I just bought one for $6.60 and then realised it was for aquariums and only goes down to 16C


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## warra48 (2/7/08)

I bought a couple more recently at my local HB shop. for about $3.50 each. I needed them for my 2nd and 3rd fermenters.
For my purposes, I think they are accurate enough. I don't really care if they are 1 or even 2C out. Having said that, I have noticed that my ales tend to go to sleep once the strip gets down to about 16C, so that tends to fit in with what I would expect the yeasts to do.


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## Kai (3/7/08)

Thirsty Boy said:


> mine generally reads just about the same temperature as the thermocouple I have attached to the outside of my fermentor - and after several experiments comparing temp readings from a sensor in a thermowell in the wort; and the sensor attached to the outside, they are effectively the same thing.
> 
> So I say that the strips are (within a reasonable margin of error) giving you a pretty good description of the temperature of your wort.




Well, you're saying that your strip is. I agree they're almost always close enough though, the most frustrating thing with my current crop of thermostrips is they're really freaking faint... I can barely read them.

I would say though that they're a great guide and generally fine. You'll soon learn if they're inaccurate, say if it reads 30 midwinter on an empt fermenter.


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## EK (3/7/08)

Kai said:


> Well, you're saying that your strip is. I agree they're almost always close enough though, the most frustrating thing with my current crop of thermostrips is they're really freaking faint... I can barely read them.
> 
> I would say though that they're a great guide and generally fine. You'll soon learn if they're inaccurate, say if it reads 30 midwinter on an empt fermenter.



I have noticed this too. I have some older ones that are very easy to see and on my main fermenter I have both an old an a new. This shows me that the old one is just as accurate as the new one, but it is also easier to read. I also have a new one sitting on my desk, in bright lighting, and I still can't read it (I am pretty sure that the room temperature fits in the range ).

:icon_cheers: 
EK


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## drsmurto (4/7/08)

They are pretty bloody robust beasts too. I sparge into a fermenter with the thermo sticker on the outside and at the end of the day when its been rinsed, sanitised and filled with lovely wort it reads the same temp as the thermo on the plate chiller....


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## warrenlw63 (4/7/08)

DrSmurto said:


> They are pretty bloody robust beasts too. I sparge into a fermenter with the thermo sticker on the outside and at the end of the day when its been rinsed, sanitised and filled with lovely wort it reads the same temp as the thermo on the plate chiller....



+1 I used to have one on my ally kettle to work out when my wort was chilled enough for pitching temps.

With the might of a NASA burning underneath it I can safely say the poor old sticky therm never missed a beat.

Warren -


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## brettprevans (4/7/08)

I think they arent too bad. they are certainly better than nothing. its the quick extreme temp change (like boiling a heap of boiling water into a fermentor) that stuffs them up.


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## Fourstar (4/7/08)

Wow, to handle 100+ degree's thats quite good.

I can say mine have been relativly accurate to compared to Thermo tests i do when taking SG readings.

maybe have been dropped had boiling water over them, scratched and all going strong. The glue on the back of them is just as robust!


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## Wolfy (16/1/09)

_(Old thread I know)._

Today when my ale yesties were still mostly sleeping after a day in the fermenter with the strip thermometer reading 20-22, I checked the wort temp with the 'normal' thermometer and found that it said the temp was really at 15. 
Seems the little plastic strip is a bit out  ... if they're within 1 deg or so for everyone else, I'll get another and hope that it works better than this one.


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## afromaiko (16/1/09)

You bet! They're as accurate as your elbow.


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