calibrating thermometer?

Question

I would like to know best way to get exact temperature within +- 5 degrees, I thought of putting in boiling water ( 212 degrees ) but not sure if water stays at 212 or gets hotter. This is for a smoker which needs to be at 200 to 225 degrees.tnx

Answer 1

You can calibrate it using boiling water, but you may have to adjust it for altitude. See calculator at
http://www.csgnetwork.com/prescorh2oboilcalc.html

If anywhere between 200 and 225 is OK, then just boil it. At 5000 feet, it's 202. Unless you're over 5000 feet, that will be within your tolerances. But the water won't get any hotter -- the extra energy will be used to convert the water to steam.

But if you need ±.5 degree, buy a cheap oven thermometer.

ps Water won't tell you anything about the upper temp. Again a cheap oven thermometer would work here.

Answer 2

Boiling water in an open container, at normal atmospheric pressure (14.7psi) has a temperature of 212°F (100°C) and will NOT vary.
A container of ice and water will stay at 32°F (0°C) as long as the ice doesn't all melt.

Answer 3

As long as you have water and steam in equilibrium, the temperature will stay very close to 212. The temperature can't go much higher (except if you use some fancy tricks to superheat the water without it boiling) until you boil off all the water into steam.

Answer 4

You can not calibrate it by boiling water. Water boils at different temperatures according to atmospheric pressure.That is why a pressure cooker works so well. You raise the pressure and water boils at a higher temperature.