Analogue Thermometer Accuracy

[gardenfiend138]

So I just thought I'd post this because I found it interesting.
I got my first temp gun a month or so ago, and was checking the temperature of everything and anything I could get my hands on for fun. I decided to pull out some old analogue thermometers (Zilla and Flukers) and set them up in the tank to see how accurate they are, and I was really surprised. They are both accurate within less than 2*F (laying down on substrate, left in for a day to make sure they were getting a good reading).
Then I checked the digital ones I bought, and they were actually less accurate at times--but only because the design of the probe doesn't allow it to come into complete contact with the bottom surface (it remains at least a few mm away from the glass, or gets a bit of substrate under it, which drastically skews the reading).
To be clear, I took readings form the top of the analogue thermometers, and from the area they were sitting on.

Don't know why I wrote so much over something so little, but I'm always reading people who just regurgitate and then embellish things they hear (i.e.- analogue thermometers are horrible). Now I'm not saying to ditch our digital tools and go buy these, but it just came as a shock after all I've read from countless people. I know a 2*F difference is unacceptable for most, which is why temp guns rock. And I'm sure many of the horror stories from analogue users were due to human-error (putting on side of tank), but using analogue tools properly (at least in the case of my 3+ year old thermometers) for cool side measurements isn't as inaccurate as some people might say.

More information to bore you with- I only took readings from the un-heated side of my tanks with the thermometers, so I'm sure they vary much more when using to gauge temperature for a hot spot (even in light of this new information I wouldn't trust them to that). Also, temp gun is a zoo-med one (I know, lame right?), but I checked it against about 10 varying temperatures with a PE tempgun, and it was accurate within at least .5*F (not saying that is a proper calibration technique, just that it reads acceptably comparable to a high-quality temp gun).

Once again this is not a post saying analogue thermometers are acceptable to monitor enclosure temps all over, but at least for me they cut down on checking cool side temps, which is what I struggle with more with that side not being on a thermostat and no heating and all...anyway, sorry for the bore.

[kitedemon]

Digital thermometers are certainly can be very very accurate but the cost of accuracy can be extreme. Few are willing or even able to spend the cash for a truly accurate digital one. The unit I use at work was over 600$

The issue is constancy during manufacturing. Cheap digital thermometers work based on electrical resistance at different temperatures very small amounts of resistance. A poor wire bad solder joint, bad contacts, bad board or anything else will throw off the readings.

Analogue are usually a bi-metal spring the ability to have two metal springs the same size constantly is not very difficult. The problem with some analogue ones is the cardboard face. They are often not assembled well. The advantage is that you can go to the store and check as many as they have and find a bunch that read the same, typically that makes them accurate as needed.

The fact they can really only measure the ambient air temp is a second disadvantage as this is one of three measurements that are needed. The others need a probe to get easily.

[Skittles1101]

Digital thermometers are certainly can be very very accurate but the cost of accuracy can be extreme. Few are willing or even able to spend the cash for a truly accurate digital one. The unit I use at work was over 600$

The issue is constancy during manufacturing. Cheap digital thermometers work based on electrical resistance at different temperatures very small amounts of resistance. A poor wire bad solder joint, bad contacts, bad board or anything else will throw off the readings.

Analogue are usually a bi-metal spring the ability to have two metal springs the same size constantly is not very difficult. The problem with some analogue ones is the cardboard face. They are often not assembled well. The advantage is that you can go to the store and check as many as they have and find a bunch that read the same, typically that makes them accurate as needed.

The fact they can really only measure the ambient air temp is a second disadvantage as this is one of three measurements that are needed. The others need a probe to get easily.

+1....if I am going to take accuracy advice from ANYONE I've ever come into contact with it's this guy right here. I've seen his posts. I don't think it's so much spewing things people have heard about analog, many people have tried and found that they were frying their snakes. I was one of those people. I had two nifty $10 analog guages from a pet store and cranked up my dimmer (thermostat now...but was only a dimmer when I first started). I then saw a cool temp gun for sale...pointed and shot. HOLY !!! My temps were 113 degrees on the hot spot. The analog was steady at 90 degrees. People recommend digital because they have a probe that can be placed anywhere in the tank. Are they more accurate? Some are, but I have seen some really crappy digital thermometers also. Most new people who come to this site have generally already spent a ton of money on their new setups and snakes only to realize everything was crap. Most, including myself, generally recommend cheaper digital thermometer (accurite). It's probably not the most ideal or accurate thermometer, but for a budget it works. Do I wish I could afford a high end +/-1 thermometer, analog or digital? Of course, but I have 5 snakes, soon to be 8, I'll take the +/-2 and save some money and just make sure it reads a steady 90, that way I never go over or under the recommended temps. Would I buy +/- anything more then 2? Probably not, I'[d stop buying snakes if it resorted to that. I'm not an accuracy expert by any means, I actually hate math....and gadgets....and anything that has to do with numbers....but through trial and error I've found what works for me. As others have, which is generally the advice given here, personal advice. I've seen some people swear by products that I personally tried and returned the next day because I found it so horrible.

[kitedemon]

I think analogue ones are fine for measuring ambient air temps. They cannot be used for hot spot or cool spot temps. They just don't work that way. Instruments are as good as the person using them. Understanding what it is capable and what it is poor doing.

Analogue dial types can be accurate (not always). They cannot be used to measure surface temps the way they are configured. They can be mounted to give the keeper more information but certainly cannot replace a probe in hot and cool hides. At least I like having one in both I know many whom only use hot.

It is a real hard issue and diligent keepers spend lots of time and effort to test, control and measure temps and humidity. It is frustrating when you find the instrument is not as accurate as expected.

My opinion is buy more than one, 3 at least and 5 is better. You can check them against each other and use the two (or 3) that read the closest. I usually buy the cheapest possible to keep the costs down. Personally I use a hygrometer as a general over all average, understanding that inside the hides will be a bit higher than average. That allows me to use thermometers inside the hides and a analogue hygrometer and digital thermometer for ambient readings. I have a couple of combo temp/hygros that work but in most cases the hygrometer is not bang on and has a little note on the enclosure add 11% or subtract 21%. Sometimes they are out but not nice even amounts but high one moment and low the next this makes it useless and I toss them at this point.

[gardenfiend138]

Thanks for the replies you two. And most definitely, I respect what kitedemon has to say as he always has some sort of evidence to support it.
I like the idea of just checking the ones on the shelves to see which are within the closest range, it's so simple but I wouldn't have thought of that.

And just to add to the test, analogue definitely ARE terrible for measuring hot side temps (was off by about 6*F, only tested one thermometer because I figured it would be inaccurate), but since ambient temps are just as important, it seems that everything has a place and a purpose then.

I was just so shocked at first to realize they did have some value to them...made me glad I threw them in a drawer rather than in the trash!

[kitedemon]

Likely sticking on the stupid cardboard face. There are better on the market but the cost is just as much as mid priced digitals and personally I see no advantage.

Again the only use (for the those whom skim read) for the dials in my mind is as an ambient air temp in addition to hot side digital probe and cool side digital probe.