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pull_my_butt 08-25-2013 06:54 AM

Temp. reading on thermometer
When I don't have to cook for a lot of people, I sometimes just use the kettle for smoking. I don't have the kettle version with the thermo. attached to the lid so I just stick a dial thermo. in where the top vents are.

If I place the thermo. into the top vents, it reads 275. When I move it to where the grate area is, it's 225. I've done this repeated times and I can see the thermo. dialing up or down as I move it.

One would think that the closer you are to the heat source, the hotter it would be. However, according to this thermo., the further up from the heat source/coals the hotter it is.

Is anyone else experiencing this? Why is this so? Which reading of the temp. would you go with?


Kloogee 08-25-2013 06:59 AM

I haven't done the same experiment, but heat does rise, so it makes sense it would collect at the top near the dome.

Banjoe 08-25-2013 07:05 AM

You're absolutely right that the heat source is the hottest place so you must be measuring something else. Not doubting what you've done, but perhaps the upper area is getting the rising heat directly above the coals while the lower temperature on the side is measuring the internal air flow down the side of the enclosure. To get your readings (which, again, I believe are accurate), I can picture air currents rising directly above the coals to give you high temp reading, and then rolling down all sides of the cover back to the coals, giving you a lower temp on your thermometer.

If you bank your coals along the outside of your BBQ and read at the top and just above the heat, do you get the same temperature differences?

Banjoe 08-25-2013 07:08 AM

Forgot to add the heat doesn't rise. It actually goes in all directions. What does rise is warm air and as this rises, something has to flow in to take its place. This is what I can imagine is happening within the closed BBQ. I never thought of this occurring in such a tight space, but you may have tripped over something that we're all working with without even realizing it. You may be remembered as a great discoverer because of this phenomenon.

Bludawg 08-25-2013 07:10 AM

Get a $5 oven therm and put it on your grate, heat rises and the meat will act as a heat sink giving a false reading if your probe is to close. Oven therms are less affected by this and give a more accurate reading.

SmittyJonz 08-25-2013 01:00 PM

Them cheap oven therms have always been one time or less use for me cuz smoke blackens glass on inside.....get an ET732.

sbshaveice 08-25-2013 01:08 PM

This is why firefighters are taught to keep low.

landarc 08-25-2013 01:21 PM

The dome it the kettle concentrates the hot air as it rises, you are getting a measurement of the air, which is heated, at the top of the lid. The air at the grate, for various reasons, is not going to read as hot. This has always been the case, and is the case for all smokers. I use a long probe thermo in the top vent, but, the tip is only 2" above the grate. Of course, if the kettle is fairly full, which I prefer, this thermometer cannot be used. I also use an over thermometer, and it has worked fine for me. I also have a Maverick, which also works, but, is more bother when I am doing something really simple, and all I want is a pit temperature.

In truth, I often cook without a thermometer at all, as I know my cookers and have a good feel for where they are sitting. Best to not have to rely on equipment.

Bludawg 08-25-2013 03:11 PM


Originally Posted by SmittyJonz (Post 2601051)
Them cheap oven therms have always been one time or less use for me cuz smoke blackens glass on inside.....get an ET732.

They have this new invention called Commet takes that stuff right off so do oven cleaner.

Bludawg 08-25-2013 03:12 PM

oops double post:redface:

SmittyJonz 08-25-2013 03:54 PM

Not on the inside.......

Bludawg 08-25-2013 04:47 PM


Originally Posted by SmittyJonz (Post 2601215)
Not on the inside.......

Pop the bezel they come out real easy clean the glass & pop it back in.

pull_my_butt 08-25-2013 06:29 PM

Hey Banjo,

I hadn't tried banking the charcoal along the outside of the kettle. I just use the charcoal baskets on each end of the grate.

I was thinking about the heat rising too but in more general terms. By that I mean heat rises and cool air falls, as we all know. In this case, it's all hot air rising but the heat that traveled the furthest from the heat source/coals is hotter than the heat right near where the coals/meats are.

And who said BBQ isn't a science and un-sophisticated? Haha. I don't know. Maybe my reasoning is off and I'll have to check a high school science book or something.

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