I just got a new stick-on thermometer for aquariums and put it on the table before i use it on my next batch... but i noticed it seems to always show 21/22 degrees, even when I "think" the room temp is much lower than that. Or at least the room temp should be changing because today is much colder than yesterday, but still shows 21/22*C. I put it against my arm and it goes up to the 30s but I don't know how to make sure this is working. Will do more damage than good if I find out it is not. Any suggestions? I dont have any other thermometer to compare obviously.
Testing stick-on thermometer??
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cluckk
Well-Known Member
Can you get a hold of this one? It is in Fahrenheit, but if you look you might find one in Celsius. It tells you the temp in ranges for lager or ale. None of these are going to be perfectly accurate. They are more to warn you of a large temperature problem. Use a quality probe thermometer to know exact temperature. Since I don't need perfectly exact in the fermentation area--just to hit the right range--I use a digital laser thermometer. I can quickly check several carboys at one time and know if there is a problem. When I pull a sample I check it with the probe thermometer to make sure my temperature adjustment is correct for my hydrometer. Exact temperature (down to the degree) is most essential in the mash. For that I use the metal probe thermometer that I check occasionally for accuracy with a high quality digital thermometer.
By the way, when laying it on the table you want to know the table top temperature. Don't assume it is always the same as air temperature. Different surfaces can vary from air temperature for many reasons. Perhaps it is getting sunlight from a window; perhaps something warm or cold was recently placed on it; perhaps the room was warmer at one point and it is taking a while for the table to cool to the new air temperature; etc. You can even easily get different temps from different surfaces in different locations in the same room--even if they are the same material. Your body (the temperature of your arm) regulates itself biologically. The table simply works as a heat sink, heating and cooling to ambient according to its properties and location.
By the way, when laying it on the table you want to know the table top temperature. Don't assume it is always the same as air temperature. Different surfaces can vary from air temperature for many reasons. Perhaps it is getting sunlight from a window; perhaps something warm or cold was recently placed on it; perhaps the room was warmer at one point and it is taking a while for the table to cool to the new air temperature; etc. You can even easily get different temps from different surfaces in different locations in the same room--even if they are the same material. Your body (the temperature of your arm) regulates itself biologically. The table simply works as a heat sink, heating and cooling to ambient according to its properties and location.
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nasty_rabbit
Well-Known Member
Noz03 said:
These thermometers are not a precision item but you could "test" it, try an extreme range. You stated that you do not have a thermometer to compare it to but you could use the buildings thermostat. You have a general idea what the room temp is and could use that as an indicator. Place it in a refrigerator for a few minutes and it should go to the lowest setting, remove it and set it on or near the thermostat. Monitor the change, it shouldn't take more than a minute or two. You should get a general idea of how close it is.
Hmm, well I know it is not so accurate but I really feel like something strange is going on with this one. I've never used them before though to be honest so its hard to tell. I dont have a building thermostat or anything other than the weather report and my own senses... but last night I didnt feel cold at all and it said 21/22, then today I felt it was definitely a bit colder, also the weather report confirmed the outside temp was 5*C lower, but it still showed around 21* on thermometer. Is it even possible for these things to malfunction in this way? they seem to be made from just a strip of paper/plastic so I dont think I could have broken it somehow.
nasty_rabbit
Well-Known Member
Typically these don't show a full range like 32 to 212f (0 to 100c) and will "light up" two or three temperatures. I doubt that it is broken but it really is just a primitive method to get an idea of how close you are to temp. Mine ranges from 36 to 78f and is now reading ABOUT 71f but actual ambient temp is 77f. So you've at least got an idea of what you have.
hmm... a bit useless to buy it i guess. If I had a regular glass air temp thermometer, then add a few degrees during fermentation would that be more accurate do you think? Another thing about my stick on is, can barely read what its showing, very faint changes in colour :/
nasty_rabbit
Well-Known Member
Not necessarily useless. The one that I have (in the picture) is just stuck to the side of a carboy. I know that it is not dead on accurate but I use it as a guide. The one you have may be alright if you target the lower end of the yeasts range (60f/15c for ales) you will have some room to be "off" by a few degrees. If your fermentation is sluggish, let the temperature climb by 1 or 2 degrees over a couple of days until it kicks off then remember that temperature for the next batch. Just remember that cooler is going to be better than warmer.
