Which of these temp/humidity readers would you trust more?

I have an electronic sensor inside of my terrarium which is hooked up to a Repti Fogger for humidity control, and I also have a Zilla temp/humidity gauge stuck in there. Even when they're side-by-side, the sensor will read temperatures about 5 degrees higher than the gauge, and humidity about 15% higher. So, for example, if the sensor says that temperature is 90 F and humidity is 65%, the gauge will say 85 F and 50%. I've since moved the gauge to the cool side of the tank just to get a general idea of the temp over there, and I've left the sensor on the hot side to make sure the air doesn't get too toasty.

My question, though, is this: which would you say is more accurate? Although the sensor is more expensive and high-tech, I'm inclined to trust the cheap plastic gauge since it ISN'T electronic and is thus probably less likely to screw up...

I'm not really concerned, just more curious. I've been using my own intuition and what I've gathered from observing his behavior to determine what changes need to be made, if any.

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Originally Posted by Lion

I have an electronic sensor inside of my terrarium which is hooked up to a Repti Fogger for humidity control, and I also have a Zilla temp/humidity gauge stuck in there. Even when they're side-by-side, the sensor will read temperatures about 5 degrees higher than the gauge, and humidity about 15% higher. So, for example, if the sensor says that temperature is 90 F and humidity is 65%, the gauge will say 85 F and 50%. I've since moved the gauge to the cool side of the tank just to get a general idea of the temp over there, and I've left the sensor on the hot side to make sure the air doesn't get too toasty.

My question, though, is this: which would you say is more accurate? Although the sensor is more expensive and high-tech, I'm inclined to trust the cheap plastic gauge since it ISN'T electronic and is thus probably less likely to screw up...

I'm not really concerned, just more curious. I've been using my own intuition and what I've gathered from observing his behavior to determine what changes need to be made, if any.

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Do you have a cell phone or old rotary phone? Do you still use paper maps or GPS? Embrace technology...ignore cheap stick on guages...:)

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Originally Posted by sho220

Do you have a cell phone or old rotary phone? Do you still use paper maps or GPS? Embrace technology...ignore cheap stick on guages...:)

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Ahahaha, and I suppose it would help for me to know exactly how the plastic gauge works, eh? :oops: My initial thought is just that the sensor is a thousand times more complicated than the gauge... but maybe I'm just a bit wary of electronics, since they more often than not seem to dislike me.

If the dial is an expensive, scientifically calibrated one with the +/- rating on it, maybe.

Most of them are not calibrated properly, so I suppose if you had the time to perform a manual calibration yourself it would work OK...

To be completely honest, neither are very reliable.

The big question on the dial type is if it has a cardboard baking or metal. The cardboard backed dials start to read further and further off as the cardboard swells due to the moisture. Metal backed dials are much better, and usually have the ability to be calibrated (using the salt test to calibrate it)

Electronic sensors have a similar issue. The older they are the less reliable they get. Even still 5% off each other is actually very good. Both devices probably have +/- 5% or even +/- 10% error built into them.

Accurate thermometers and hygrometers are very expensive, hundreds to thousands of dollars. This means that most people in the reptile hobby aren't going to be able to afford them. What people need to find are precise (see precision vs accuracy below) thermometers and hygrometers that can be relied upon to give consistent readings. Even if they are incorrect. That way you can over time learn how far off the readings are and compensate for them.


Precision vs Accuracy:


http://i1186.photobucket.com/albums/...9.jpg~original

Accuracy is the measure of correctness, in terms of the picture closer to a bullseye

Precision is the measure of consistency, in terms of the picture closer groupings.

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Originally Posted by Lion

Ahahaha, and I suppose it would help for me to know exactly how the plastic gauge works, eh? :oops: My initial thought is just that the sensor is a thousand times more complicated than the gauge... but maybe I'm just a bit wary of electronics, since they more often than not seem to dislike me.

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I think this is how the cheap plastic guages work...

Metal Coil Thermometers (thermostats)

As with liquid thermometers, the metal winding expands or contracts in response to the energy absorbed from the air or liquid around it. This expansion pushes the end of the metal indicator back and forth in the dial face.

Hovabator incubators use this type of "wafer" thermostat...


Here's how the fancy infrared temp guns work...

The infrared gun detects the heat signature of an object with optic sensors. These sensors are a series of lenses and mirrors that condense the infrared energy that an object omits onto a detector that transforms the infrared energy into an electrical signal. This signal is interpreted and turned into a temperature reading on the gun's display.

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Originally Posted by Mephibosheth1

If the dial is an expensive, scientifically calibrated one with the +/- rating on it, maybe.

Most of them are not calibrated properly, so I suppose if you had the time to perform a manual calibration yourself it would work OK...

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You're right, that never occurred to me. Of course, I'm no engineer, so I guess I'm sticking to a rough estimate on the cool side of the terrarium. :aww:

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Originally Posted by The Serpent Merchant

To be completely honest, neither are very reliable.

The big question on the dial type is if it has a cardboard baking or metal. The cardboard backed dials start to read further and further off as the cardboard swells due to the moisture. Metal backed dials are much better, and usually have the ability to be calibrated (using the salt test to calibrate it)

Electronic sensors have a similar issue. The older they are the less reliable they get. Even still 5% off each other is actually very good. Both devices probably have +/- 5% or even +/- 10% error built into them.

Accurate thermometers and hygrometers are very expensive, hundreds to thousands of dollars. This means that most people in the reptile hobby aren't going to be able to afford them. What people need to find are precise (see precision vs accuracy below) thermometers and hygrometers that can be relied upon to give consistent readings. Even if they are incorrect. That way you can over time learn how far off the readings are and compensate for them.

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AWESOME info, thank you!

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Originally Posted by sho220

Here's how the fancy infrared temp guns work...The infrared gun detects the heat signature of an object with optic sensors. These sensors are a series of lenses and mirrors that condense the infrared energy that an object omits onto a detector that transforms the infrared energy into an electrical signal. This signal is interpreted and turned into a temperature reading on the gun's display.

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I know that my dad has a temp gun (the guy spent twenty years building houses, and now works as a home inspector for houses on the market, so he's got ALL the goods), so this should be really helpful as well. ;D

Honestly I only use the thermometer as a general idea. I know if it get's to 88 then it's approaching 93. If it's at 86 then it's 92, and 84 is at 91. It's the acurite thermometer as well. I do my final checks with the temp gun.

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Originally Posted by Lion

AWESOME info, thank you!



I know that my dad has a temp gun (the guy spent twenty years building houses, and now works as a home inspector for houses on the market, so he's got ALL the goods), so this should be really helpful as well. ;D

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Temp guns are great to have...and you can get them for less than 20 bucks at Lowes/Home Depot/etc. Great investment and makes it so easy to check temps...

Are the temp guns more accurate??

I just wonder now about the accuracy of the Acurite I have....Maybe I should get a heat gun too...



@Serpent Merchant: what is the "Salt Test"??

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Originally Posted by Mephibosheth1

Are the temp guns more accurate??

I just wonder now about the accuracy of the Acurite I have....Maybe I should get a heat gun too...



@Serpent Merchant: what is the "Salt Test"??

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No they aren't, at least not the cheap ones used in the hobby. Most are actually worse.

Salt Test: http://www.cigarpass.com/cigars-101/...ygrometer.html

so you would or wouldn't recommend one??

I currently just go off my accurite probe for judging the hot spot, and assumed that the reason acurite was so widely used was due to the accuracy of its measurements...

I forgot the part in Chemistry about accuracy vs. precision :p

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Originally Posted by Mephibosheth1

so you would or wouldn't recommend one??

I currently just go off my accurite probe for judging the hot spot, and assumed that the reason acurite was so widely used was due to the accuracy of its measurements...

I forgot the part in Chemistry about accuracy vs. precision :p

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Temp guns are a great tool, don't get me wrong. I have one and use it all the time, but people need to realize that they aren't any more accurate than most decent digital thermometers. Most are at least +/- 4 F, that is about the same as an acu-rite. The really cheap temp guns can be even worse.

I would recommend temp guns mainly to people who use rack systems, that is really what they are best for. $ for $ temp guns just don't make a huge amount of sense unless you have a very large collection. Why pay $125 for a temperature measuring device that isn't any more accurate than a $12 unit? Why pay $40 or $50 for one that is worse than the $12 unit?

The cheap temp gun I got at Lowes a few years ago is always within 1 or 2 degrees of what my Herpstats are set to. I've had several Accurites and they're all over the place...i.e...+/- 10-20 degrees...

I'm not sure what temp guns you use but the one that I use is within a degree of my herpstat reading. It's was also within a degree of my vivarium electronics thermostat.

You can look up the datasheets yourself. I have a PDF of one somewhere I will try to find a post.

Just because yours read true doesn't mean they are accurate. When the manufacturer lists an error of +/- 4 F they do so because they know the limitations of the components used. The point of a toll wrench is that it is a range. Sure it can read spot on, but another day/another temp gun of the same model could be + 4 F. Some of my Acu-Rites read true, others not so much. The facts of the matter is that you are getting something rated for the same tollerence. A temp gun $50+ is going to be better, but is it 5x better?

Here is the data sheet:

http://i1186.photobucket.com/albums/...e.jpg~original

These are nearly $100 temp guns from a good brand, and they are only rated for +/- 3 F

So how can I make sure my Acurite is actually readi the right temperature??

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Originally Posted by Mephibosheth1

So how can I make sure my Acurite is actually readi the right temperature??

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You need something to compare it to. Something like a herpstat probe that is rated to be accurate. I know some people recommend buying 3-4 acurites and then averaging their readings. That is a bit extreme, but would work.

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Originally Posted by The Serpent Merchant

You need something to compare it to. Something like a herpstat probe that is rated to be accurate. I know some people recommend buying 3-4 acurites and then averaging their readings. That is a bit extreme, but would work.

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lol...would be cheaper to just say screw it and guess...:D At least with a temp gun you can run around your house in the winter and find out where that darn draft is coming from! And apparently you can use them to find dead cylinders in a cars engine...:confusd: