Calibrating your themostat/thermometer?

[Chondrobsessed]

Hi guys,
I'm just testing out my new dimming thermostat and I'm getting really mixed results when comparing to my thermometer.
They seem to have a non linear relationship, the probes are within 1.5cm of each other but temps differ from 0-2 degrees Celsius. They both have a display accuracy of +/- 1 degree so I suppose its possible for one to be at +1 and one to be at -1, but how do I know which one is telling the truth? Are the analogue dial thermometer more accurate at stable temps?
What thermometers to people your for incubation as I assume you would want them telling the truth? I'm not using them for incubation but for a small enclosure that is empty at the moment.
So what do you use to calibrate your heating equipment?
Thanks!

 

[loungelizard]

I use a old school high quality glass thermometer as a control.
But dont panic your only talking a degree or two.

 

[Ramsayi]

The thermometers you are using are precise but they are not accurate.

If you have one that is able to be immersed make up a slurry of ice and water, drop the probe into it.It should read 0c ,if it is out by a degree or two just make an allowance for it.You can then measure other thermometers off that one again making whatever allowances are needed for each one.

 

[Jarrod_H]

I use a old school high quality glass thermometer as a control.
But dont panic your only talking a degree or two.

exactly what I was gonna say

 

[Chondrobsessed]

Hey just in case anyone else has had or will have this problem I have found he problem/solution.
I now have the same temperature reading almost all the time, occasionally out by 0.1 degree and rarely by 0.2 degree.
I had the thermometer & stat probes too close to the heat source (globe), I guess the non homogenous heat and different response rates where the reason I was getting such varied measurements.
I only dropped them about 4cm and now I'm very happy with the temperatures.

 

[Fluffysnake]

I am very pedantic with temps ( you kinda have to be.)
I have several digital probe thermometers, twin zone thermometers specifically for reptiles, and a dial thermometers.
They all say different temps
Then I bought an Infra-red thermometer - expensive but worth a pets life i suppose.
It's ideal for setting up as it shows true surface temps. you can even point it at the snake - 29C - PERFECT!!
I only use a twin zone thermometer as an indicator of a problem with the thermostat.

 

[saximus]

I am very pedantic with temps ( you kinda have to be.)
Then I bought an Infra-red thermometer - expensive but worth a pets life i suppose.

No, you don't have to be. One or two degrees off will never kill an animal.

 

[Hoplophile]

I calibrate with a laboratory grade glass thermometer. Mercury is best but regarded as a little on the dangerous side these days...break it and you'll end up breathing mercury vapour (metallic mercury will evaporate to some degree at room temperature). Red alcohol glass lab thermometers are a next best choice. Available from scientific supply stores.

It's possible that slight variations can be cause by the propensity of the different materials used in your thermometers to absorb heat differentially in air or from radiant heat sources. Therefore using an ice slurry will be more accurate for low temperatures and I'd use warm water up around 30 degrees to see how they compare at temperatures you're most interested in.

 

[Fluffysnake]

I am very pedantic with temps ( you kinda have to be.)
Then I bought an Infra-red thermometer - expensive but worth a pets life i suppose.

No, you don't have to be. One or two degrees off will never kill an animal.

one or two degrees is fine, but I was getting readings varying by as much as 8 degrees.
This makes one think "Is the average right ? or is it 1000 degrees in here?"