# digital thermometer question



## alan1 (Nov 11, 2008)

hi, im setting up a royal incubator. whats the best digi thermometer on the market to use, ie; reliability, accuracy and price?


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## sasandjo (Dec 8, 2007)

Digital Thermo Hygrometer Incubator Reptile Hatch Egg on eBay, also, Reptiles, Pet Supplies, Home Garden (end time 01-Feb-09 20:00:00 GMT)

thats what i use


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## fixitsan (Apr 15, 2008)

alan1 said:


> hi, im setting up a royal incubator. whats the best digi thermometer on the market to use, ie; reliability, accuracy and price?



Most digital thermometers available on ebay and in pet shops have an accuracy of 1 degree either way ( +/- 1C ). What that means is if the true temperature is 25 celsius your thermometer will display anything between 24 to 26 celsius

If that level of accuracy is sufficient for incubation then almost any will work.

Another specification to pay attention to is the 1% accuracy for the hydrometer. Some digital hydrometers have terrible accuracy so try to get something with a 5% accuracy or better

Just because the 'resolution' might be decribed as 0.1 degree , does not mean the device is accurate to 0.1 degree, instead it only means that the temperature plus any error can be diosplayed to a resolution of 0.1 degrees. It's a slight but significantly important point to watch out for.

At the end of the day though, what happens in nature ? Are temperatures in the wild accurate to a fraction of a degree ? They aren't normally, and so without spending upwards of £50 for a decent quality device anything commercially available with +/- 1 degree of temperature accuracy would probably be acceptable.

The only thing I might do differently for the sake of safety, would be to buy seperate instruments, then if for example one has a display failure then the other still works well and you don't lose sight of both values just because one display failed, as you do with combined instruments.

Chris


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## alan1 (Nov 11, 2008)

*digi therms*

cheers 4 all the info


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## johne.ev (Sep 14, 2008)

I use the exo-terra ones but tbh don't know how accurate they are.
What Chris says makes alot of sense. When using one of these in my incubators i often experienced plus or minus one or two degrees.


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## fixitsan (Apr 15, 2008)

johne.ev said:


> I use the exo-terra ones but tbh don't know how accurate they are.
> What Chris says makes alot of sense. When using one of these in my incubators i often experienced plus or minus one or two degrees.


The good thing about the innaccuracy is that it doesn't matter just as long as yoiu know which way the error goes.

If you have a thermometer which is reading 19 degrees when the true temperature is 23 degrees, yoiu know it reads 4 degrees too low ( and something that bad belongs in the bin but if it's all you've got then....) it will also read 4 degrees too low at 40 degrees, and at 60 degrees too.

The error, in the usual range of operation we use, say 16 degrees C to 35 degrees C, varies so slightly that we may as well assume it is a constant. As long as yoiu know which way the error goes you can use that thermometer at the end of the day, just remember to apply a correction value when you read it.

I use a 70 year old mercury thermometer to calibrate other digital thermometers against, because i know it is accurate to 0.2 degrees C (and at 50p from a jumble sale it was a bargain). I've stuck a label on the digital thermometer I use saying ' + 0.8C ' to remind me to add 0.8 C to the displayed temperature in order to correct the error and discover the true temperature.

If you are really serious about getting accurate temperature measurements then I would suggest going to Welcome to rswww.com or Farnell United Kingdom | world-leading distributor of electronic and maintenance, repair and operations products. and searching for 'digital thermometer'. A certified accuracy of better than 0.5C will cost upwards of £25, and a certified accuracy of 0.1 degree Celsius normally costs close to £100, but sometimes even these industrial suppliers have sales too !


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## bilko (Oct 22, 2008)

TBH I think these over priced temp gauges are a rip off, I've found the £2.99 ones from Lidl to be close enough as makes no difference.


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## fixitsan (Apr 15, 2008)

bilko said:


> TBH I think these over priced temp gauges are a rip off, I've found the £2.99 ones from Lidl to be close enough as makes no difference.



Precisely (!)

If you have a known accurate thermometer then you can do your own calibration of almost any new thermometer you buy. 

I would check one against your known good thermometer at 20 celsius, and again at 30 Celsius. If you have about the same error for both readings pop a sticky label onto your new probe to remind you to either add or subtract the error value, and then you have something which is as accurate as the good thermometer which you calibrated it against (for that range of temperatures)

A very accurate and readily available thermometer which can be used to calibrate all your others is the medical type. The electronic ones are accurate to 0.1Celsius in a lot of cases, but they only have a very narrow temperature range of about 32 celsius to 40 celsius (some don't even read less than 32). If you made up a cup of water so that your medical thermometer read 35 Celsius yoiu could calibrate yoiur others against this standard.

I saw digital medical thermometers on sale on Asda's '£1 shelf' recently, I bought one, and checked it and it was exceptionally accurate. For £1 you can't argue !


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