Corflute heat mat to heat aquarium from underneath?

[fourexes]

yes as mentioned earlier it's poly-carb roof sheets. expensive but if you know enough near by herpers could be very cost effective. works very well for me. I do notice if you run an infa-red thermo across it with the thermostat at say 30 the heat runs get to around 38 and the others measured close up are around 35. I've turned the thermostat to 28 and I get a temp on the heat runs of 35 and the others around 32. when measured from say 6 inches away the local temp measures 32. Something to think about when setting up, if it makes sense, sorry if it doesn't.

 

[J-A-X]

The difference you are seeing in the temp is because you haven't, or aren't able to, calibrate you infRa-red (not infa red) temperature gun.
They are not just point and shoot like many people use them.
You need to calibrate the gun for different emissivity of the object you are trying to test.
For those that are curious- here's the definition of emissivity:

The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.

In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.

End of definition !

In laymans terms it measures the reflected heat, not actual surface temp. I always set my heat up with a common mercury thermometer WHERE THE REPTILE WILL BE. Thus avoiding any possibility of burns.
I have an IR gun that I regularly use to check my heatcords are working as it doesn't disturb the animal

Like they say 'a little knowledge can be a dangerous thing ' and to use only an IR gun could result in your animal having a less than optimal basking spot

I know this is off topic but IR guns have been mentioned a lot recently and this seemed an ideal time to get this info out there.

 

[Renenet]

I know this is off topic topic but IR guns have been mentioned a lot recently and this seemed an ideal time to get this info out there.

No worries, Jax. This thread has turned out to be more informative than I thought it would be!

 

[Snowman]

Most of the name brand temp guns are very accurate though. I've tested my fluke with the high tec thermometers at a processing plant and got readings within .2 degrees. I trust my fluke temp gun more than my digital and mercury thermometers.

 

[andynic07]

Most of the name brand temp guns are very accurate though. I've tested my fluke with the high tec thermometers at a processing plant and got readings within .2 degrees. I trust my fluke temp gun more than my digital and mercury thermometers.

Are mercury thermometers more designed for ambient air temperature rather than surface temperature?

 

[Snowman]

The difference you are seeing in the temp is because you haven't, or aren't able to, calibrate you infRa-red (not infa red) temperature gun.
They are not just point and shoot like many people use them.
You need to calibrate the gun for different emissivity of the object you are trying to test.
For those that are curious- here's the definition of emissivity:

The emissivity of a material is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have an ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity.

In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Highly polished silver has an emissivity of about 0.02.

End of definition !

In laymans terms it measures the reflected heat, not actual surface temp. I always set my heat up with a common mercury thermometer WHERE THE REPTILE WILL BE. Thus avoiding any possibility of burns.
I have an IR gun that I regularly use to check my heatcords are working as it doesn't disturb the animal

Like they say 'a little knowledge can be a dangerous thing ' and to use only an IR gun could result in your animal having a less than optimal basking spot

I know this is off topic but IR guns have been mentioned a lot recently and this seemed an ideal time to get this info out there.

Five Ways to Determine Emissivity
There are five ways to determine the emissivity of the material, to ensure accurate temperature measurements:
Heat a sample of the material to a known temperature, using a precise sensor, and measure the temperature using the IR instrument. Then adjust the emissivity value to force the indicator to display the correct temperature.
For relatively low temperatures (up to 500°F), a piece of masking tape, with an emissivity of 0.95, can be measured. Then adjust the emissivity value to force the indicator to display the correct temperature of the material.
For high temperature measurements, a hole (depth of which is at least 6 times the diameter) can be drilled into the object. This hole acts as a blackbody with emissivity of 1.0. Measure the temperature in the hole, then adjust the emissivity to force the indicator to display the correct temperature of the material.
If the material, or a portion of it, can be coated, a dull black paint will have an emissivity of approx. 1.0. Measure the temperature of the paint, then adjust the emissivity to force the indicator to display the correct temperature.
Standardized emissivity values for most materials are available (see pages 114-115). These can be entered into the instrument to estimate the material’s emissivity value.

 

[Snowman]

Are mercury thermometers more designed for ambient air temperature rather than surface temperature?

They would certainly be affected by ambient air temps.

 

[Snowman]

The other thing with temp guns is that laser pointer is just that. A pointer. The sample area is like a cone and you get the average temps within that cone sample. The red dot is not the exact spot you are measuring.
Unless the surface is quite reflective you shouldn't get any false readings.

 

[andynic07]

Five Ways to Determine Emissivity
There are five ways to determine the emissivity of the material, to ensure accurate temperature measurements:
Heat a sample of the material to a known temperature, using a precise sensor, and measure the temperature using the IR instrument. Then adjust the emissivity value to force the indicator to display the correct temperature.
For relatively low temperatures (up to 500°F), a piece of masking tape, with an emissivity of 0.95, can be measured. Then adjust the emissivity value to force the indicator to display the correct temperature of the material.
For high temperature measurements, a hole (depth of which is at least 6 times the diameter) can be drilled into the object. This hole acts as a blackbody with emissivity of 1.0. Measure the temperature in the hole, then adjust the emissivity to force the indicator to display the correct temperature of the material.
If the material, or a portion of it, can be coated, a dull black paint will have an emissivity of approx. 1.0. Measure the temperature of the paint, then adjust the emissivity to force the indicator to display the correct temperature.
Standardized emissivity values for most materials are available (see pages 114-115). These can be entered into the instrument to estimate the material’s emissivity value.

Certainly like to do your homework or have a really broad knowledge base.

 

[Snowman]

Cut and paste... Like Jax did

 

[J-A-X]

LOL, maybe we should start another thread
Given I use no other heating than cords the merc thermometers are giving me accurate enough temps, I also have a digital probe thermometer to triple check because I don't run thermostats (and that's a separate thread on its own)

I'm not saying dont use IR guns, just wanted people to be aware that they could need to be calibrated.
I've 'played' around with mine and on some surfaces they can show 5 degree less than the mercury or digital thermometer - enough to cause severe irritation to a snake belly when I think it's 35c and its actually 40c

 

[Renenet]

yes as mentioned earlier it's poly-carb roof sheets. expensive but if you know enough near by herpers could be very cost effective.

Can you please tell me the measurements of that sheet? I'm trying to get any idea of how far away the cord "channels" are from each other.

 

[fourexes]

calibrated or not I was only using it to compare the difference in surface heat on the one surface, just looking for hot spots, which were noted. Then as mentioned measuring from a distance (increasing the measuring area) gave me a comparable average.

Thanks for the info though Jax that was informative.

I agree mercury thermometers are great, but basically anything can be inaccurate if not used properly.


Renenet: The sheet size was 600 x 2400mm with 8mm squares, available from bunnings in the roofing section if you want a good look.