Hard time calibrating digital thermometer

[eduedp]

Hi. I'm hoping we have calibration experts here

After losing some silk eggs in my incubator and reading a lot about how to calibrate a thermometer, I decided to calibrate mine.
I have a digital thermostat with external sensor.
First I calibrated using freezing point method and then I tried using water boiling method to check if calibration went correct.

But results are contradicting. See...

Thermometer registered 32.6 F inside freezing point. So I adjusted it to 32 F.
After calibration...
Thermometer registered 211 F inside water boiling. It was supposed to register 207.5 F, according to http://virtualweberbullet.com/boilingpoint.html as I'm at 30.01 inHg and 2290 ft. (I even tried using my barometer to calculate boiling point, but it was supposed to register boiling point at 207.3 F according to the results.)

So what now?
My thermometer is correctly calibrated 0 F at freezing point but 3.5 F off at boiling point.
What should I do?

Thanks.

 

[eduedp]

Where can I get help about this?

 

[HatchCraft]

Checking a thermometer at freezing or boiling won,t guarantee accuracy at 100 degs. The simplest way to check accuracy is with a digital fever thermometer. Using an insulated container, fill with warm water and adjust the temp it is 100 degs according to your fever thermometer. Use the 100 deg water to calculate the accuracy of the thermometer in question. This should be accurate enough for your purposes. The best option in my opinion is to purchase a quality mercury thermometer designed for incubation and the narrow range of temp we are concerned with. I use one to calibrate all my controller and thermostats, as well as determine the accuracy of other thermometers. Image of my daughter checking a spirit thermometer using this method.

 

[eduedp]

Thank you, good idea

I could also test my calibrated thermometer with my body temperature, perhaps.

 

[HatchCraft]

I don't see why not. Better than boiling water.