Which thermometer is correct?

Which Thermometer is Correct?

Kamado-style grills, such as the Big Green Egg, allow you to control the temperature of your cook easily, compared to some of the open metal grills we’ve all used. We all then learn to cook to temperature, not time, to get even better results. We then start using thermometers like the Thermapen and Meater, and maybe even a forced air controller like the Egg Genius. During cooking, all these devices may read a different temperature to the dome thermometer, but which thermometer is correct?

Most people just assume the Meater temperature is correct and the dome thermometer is wrong, as the Meater is digital, and technology can’t be wrong. This is the wrong assumption.

They’re all correct

Dome Thermometer

Assuming your dome thermometer has been calibrated, it will be reading the temperature of the air in the dome of your Egg. When they’re delivered, the Eggs Tel-Tru thermometer will be correct, and you should install it into the dome of your Egg the correct way up, before putting the clip on the back. You should never install it, and tighten the clip, and then twist it to level it, as you may twist the nut on the back of the thermometer against the Egg, and this will take it out of calibration.

Meater

The Meater is a superb piece of equipment. The new Pro version has five different thermometers in the probe, which measure the temperature of your meat. There is a sixth thermometer, they call ambient, that measures the temperature of the air around your meat. It is not necessarily measuring the temperature of your grill. That may seem like an odd statement, but hear me out.

The ambient thermometer of your Meater measures the temperature of the air surrounding your meat. It is correct. However, a big hunk of cold meat will cool the air around it, and your meater will measure the temperature of this cooled air. Take a look at this graph, where during this cook, the air around the meat took as long as the cook to register the temperature of the grill as the cook took. The green line is showing the ambient temperature, the purple line is showing the temperature of the meat.

If we used the ambient temperature of the Meater to set the temperature of your Egg, you would turn it right up at the beginning, and then struggle to reduce the temperature of the Egg as the air around your meat warmed up. Therefore, never use the ambient temperature of the Meater as the temperature you’re adjusting your Egg to. 

Egg Genius

The Egg Genius uses a thermometer you clip inside the Egg to control the amount of air it blows into the Egg, burning the perfect amount of charcoal to hold your Egg at the desired temperature. It relies on you closing the top vent a little more than you would have it set normally for the desired temperature so the the fan then has to push the air through your Egg. If you have the top vent open too far, the Egg may draw too much air through the Egg, and the temperature will rise.

Where should you position your Egg Genius thermometer? I’ve seen some people clip it to the probe end of the dome thermometer, that can work. The downside to this is that it’s easy to knock it off when you close the dome, and you wont necessarily know. I prefer to clip the thermometer to the cooking grate, away from your cook (so you’re not measuring the cold air around your cook), and where I can bring the wire into the Egg above one of the ConvEGGtor legs, to protect it.

You should never place the thermometer over the area the hot air will come up from the charcoal.

The Egg Genius will read the correct temperature at which the probe is placed. This may be 20°C different to the dome temperature, but as I always say, 20°C either way in a cook is going to have very little impact on the cook.

Which temperature do I use if they’re all correct?

If you poked a probe thermometer like the Thermapen into a cooked roast chicken, you’d find the temperature in the breast would be lower than the temperature in the thighs. In the same way, the temperature next to your cold meat will be lower than the dome thermometer, and the temperature immediately above the burning charcoal will be much, much higher.

If I’m using a Meater and the dome thermometer for my cook, then the dome thermometer is the one I will cook by. It’s giving you a more accurate indication of your Egg’s temperature.

If I add the Egg Genius to the equation, I will use the Genius’s thermometer and place it correctly.

I’ll say it again, I will never cook using the Meater’s ambient temperature.

If you get your temperatures right, you will achieve amazing results.

Other resources

Meater Resources

• Meater Pro – single probe version of the Meater with Bluetooth connectivity.
• Meater Pro XL – 4 probe version of the Meater with WiFi connectivity.

Egg Genius resources

• Egg Genius review.
• Egg Genius Power Options – how to power your Egg Genius from a mobile phone power bank.
• Buy an Egg Genius – we are one of the country’s leading Big Green Egg resellers and can source most Big Green Egg products for you.