Discrepency in Temps - Maverick ET-732 chamber probe vs BGE inbuilt thermometer.

Blackrazornz · December 2012

Hi all,

I recently bought a BGE (as in a week ago) and am trying my first pork shoulder on it today - have just cooked a few pizzas so far. From New Zealand so hopefully I haven't used any weird slang below!

I calibrated the BGE thermometer before first installing it by touching the tip to a pot of boiling water (i'm only 5m above sea level) and then adjusting the nut till it read 100C / 212F, then installed it.

I've got a Maverick ET-732 that I'm using today to monitor the cook. Currently the internal temp probe reads 32C (i.e 90F) and the chamber probe reads 105C (i.e 221F), with the chamber probe slowly climbing.

Problem is, the internal egg thermometer currently reads 145C! (293F)

Which one do I trust? I dont want to end up with a raw pork shoulder, nor do I want a blackened mess... Is it more likely I mucked up the calibration of the inbuilt thermometer, or that the Maverick probe is on the fritz? I've fried a Maverick probe via high heat on my old Weber before, but this is a new probe and seems to be giving consistent readings with no spiked etc and a slow gentle rise in heat - it's just not matching my Egg thermo!

Thanks in advance for any help.

Blackrazornz · December 2012

If it helps, I've currently got the bottom door open about 3/4", and the top vent has the main swing flap closed and the rotor vents fully open.

The Cen-Tex Smoker · December 2012

good news is that 290 is perfect for doing pork butts on your egg so you are safe either way. My guess is that your maverick is very close to your pork butt and the butt is still cooler than your dome. Move that thermo to another spot (but not directly over your lump or you'll get the opposite effect) and see if it balances out. It's not uncommon for there to be 10-15 degrees difference in your dome and grid temps but my guess is if you change the placement of your probe it will behave

CeramicChef · December 2012

I would recommend you read the following from AmazingRibs.com http://amazingribs.com/BBQ_buyers_guide/thermometer_buying_guide.html The bimetallic dome thermometers are essentially useless. I would recommend getting a good dual lead electronic thermometer and you've already got a good thermometer for getting multiple readings to insure you have hit the temp you are looking for. Enjoy and good on ya, mate!

Blackrazornz · December 2012

I think I just answered my own question - I had a replacement probe that I fed in through the top vent of the smoker and is just dangling in the middle of the chamber (with tin foil wrapped around the wire) and it reads 143C.. almost spot on what the BGE one does.

I'll take it that 2 similar readings mean the different one is the wrong one, so looks like I have a dud chamber probe... It's fresh out of the box too!

Blackrazornz · December 2012

Scratch that! Putting the new chamber thermometer at grill level (with the clip stuck into a Potato to hold it in place) it's now reading what the old one did.

Only rational explanation is that there is an appx 35C variance between grill level and dome level... is that a problem?

The Cen-Tex Smoker · December 2012

Blackrazornz said:

Scratch that! Putting the new chamber thermometer at grill level (with the clip stuck into a Potato to hold it in place) it's now reading what the old one did.
Only rational explanation is that there is an appx 35C variance between grill level and dome level... is that a problem?

Nope. It's common to have some difference. This seems a little on the high side but I bet they will draw closer to each other over your cook. If your butt is only 90, that will keep your grid area cooler until it comes up to temp with the dome. I bet you end up reading 10 degrees difference or so after a while

Blackrazornz · December 2012

Thanks, I'll see how it goes and report back :)

lousubcap · December 2012

All good info above but 35*C delta T is way up there-as C-T mentioned earlier make sure the grid thermo is shielded from a direct shot of burning lump-if everything's calibrated that's about the only way you would see such a difference (grid higher). Now if grid is 35*C lower-you may be in contact with the meat. FWIW-

crabboy · December 2012

I had toiled with this same problem when I first got a maverick. I later began to clip the maverick probe and now the Stoker probe to the BGE probe and the temps are now close enough. I never did like tracking two different temps, grid and dome, now all I worry about is the dome. I follow the electronic probe, but use the dial as a sanity check.

Skiddymarker · December 2012

The reality is most of us use the dome as reference, but quote grid temps for cooks, 'cause that's where the food is.

For the Mav, do not use it for direct cooks until you have lots of experience, it is very easy to fry the probe.

Put the place setter in with a leg at the back, near the hinge. Clip your Mav probe over one of the legs on the left or the right, with the cable coming out between the dome and base, the gasket will seal around it. DO NOT EXPOSE THE PIT PROBE TO BURNING LUMP. DO not hang your pit probe down thru the top vent. Do not clip the probe to the dome thermo, you just don't need to.

Generally, there will be about 15-30F difference between dome and grid temp on a stable egg.

The longer the egg is stable, the smaller the difference will become.

Don't track two temps, just track the Mav, the dome temp is for reference only on indirects. On directs dome is the temp indicator, so keep an eye on it as you do indirect cooks to see how close it is to the Mav. The egg is not a digital oven, the temps can vary as different pieces of lump burn.

Blackrazornz · December 2012

Thanks for all the advice, and yeh, I figured eventually to trust the grill-level Maverick

Pulled the pork off at 90C internal after 7 hours (was only a 2 pound piece of pork), came out alright for my first time ever :)

Skiddymarker · December 2012

@Blackrazornz - us Canucks understand C but most of the American guys still use F, go figure they tossed out the King and kept his temperature system, hell even England uses C now....

Nice looking pulled pork, try it with a Carolina vinegar slaw and sauce - really good.

;)

Blackrazornz · December 2012

Skiddymarker said:

they tossed out the King and kept his temperature system

From talking over this with the ex-pat Yankees in our town*, I've pretty much set on the viewpoint that they know the rest of the planet has it right, but they stick to Imperial just to be contrary ;))

* yes, there are a fair few, I'm pretty sure a fairly large chunk of the white middle-aged Democrat voting base moved from the US to Australia or NZ during the Bush era.

nolaegghead · December 2012

Hey, I know we're backwards, but it makes us quaint. People down here think the universe is 6000 years old and scientists are con artists. I'm going to have to one-up ya. From now on, I'm reporting all my temps in Kelvin.

Blackrazornz · December 2012

nolaegghead said:

Hey, I know we're backwards, but it makes us quaint. People down here think the universe is 6000 years old and scientists are con artists. I'm going to have to one-up ya. From now on, I'm reporting all my temps in Kelvin.

It's not quite the killer move you think, I'd just add 273 to whatever you quote and go back to drinking beer :P

Still, if it wasn't for you guys, 'BBQ' in my country would consist of mechanically tenderised minute-steaks flash fried on a stainless steel gas grill alongside some precooked sausages and the odd piece of fish. So we gotta be nice, we owe ya :D

nolaegghead · December 2012

Awwww....that's very kind. Thanks blackrazornz...

Wait, minor correction - you'd have to subtract 273 and the Fahrenheit folks would be left with Celsius (nnoooo more math!). Next sous vide project - short ribs in a Bose-Einstein condensate. Macroscopic condensate phenomena's effect on Dizzy Pig rubs...

Blackrazornz · December 2012

nolaegghead said:

Wait, minor correction - you'd have to subtract 273 and the Fahrenheit folks would be left with Celsius (nnoooo more math!).

Nah, I meant Kelvin temps work on the same scale as Celsius, they just start 273 behind (273.15 to be exact), so 0C is 273K, 150C is 423K, etc etc, easy conversion, just add 273 to the K to get C :)

I suspect before my time is done I'll be able to do a thesis on "Chaos Theory in a Barbecue Environment : A Study of Mean and Average Temperatures Required to Obliterate Sensor Probes on the Maverick ET-732 - with concordance"

CeramicChef · December 2012

Well by gollies, it seems we may have a real live international incident on our hands here! How about we report in both Kelvin AND Rankin? Can't we all just get along? Either that or learn that a real quick and dirty conversion is to take *C, double it, and add 30 to get it into *F? It's actually 1.8 x *C + 32 = *F, but ... Geez, look at that, I finally found a use for my Engineering Thermo!

lousubcap · December 2012

Been using the CeramicChef rough conversion for too many years-and in the Q world, close enough!

nolaegghead · December 2012

Blackrazornz said:

nolaegghead said:

Wait, minor correction - you'd have to subtract 273 and the Fahrenheit folks would be left with Celsius (nnoooo more math!).

Nah, I meant Kelvin temps work on the same scale as Celsius, they just start 273 behind (273.15 to be exact), so 0C is 273K, 150C is 423K, etc etc, easy conversion, just add 273 to the K to get C :)
I suspect before my time is done I'll be able to do a thesis on "Chaos Theory in a Barbecue Environment : A Study of Mean and Average Temperatures Required to Obliterate Sensor Probes on the Maverick ET-732 - with concordance"

Subtract! Subtract! If I'm cooking at 373K, you would have to subtract 273 to see I'm cooking at 100C :D

Raymont · December 2012

My new homemade Sous vide PID controller reports temps in C, so I've downloaded a Iphone app to convert over to F just so my brain can handle it.

CeramicChef · December 2012

BLACKRAZORNZ!!! OMG! You have me spool scared! I thought I was the only sick twisted freak here! Chaos theory!?? My dissertation dealt with the application of Dynamic Systems Theory (Chaos Theory is a branch of DST) to Business. We gotta get a life ... I think I'm gonna go cook something in the snow!

Blackrazornz · December 2012

nolaegghead said:
Subtract! Subtract! If I'm cooking at 373K, you would have to subtract 273 to see I'm cooking at 100C :D

You can be right all you want, but at least some of us have the privilege of being part of the Glorious Celsius Master Race
:))

nolaegghead · December 2012

hahah....well, I speak two languages when it comes to units....we use the metric system at my job and the caveman system in the wild.

Blackrazornz · December 2012

True story : When I was a young boy (like, 7 or 8), my uncle, of Canadian descent, had me totally convinced that Americans measured time in Bushels and Pecks instead of Hours and Minutes. :-S

Skiddymarker · December 2012

Blackrazornz said:

True story : When I was a young boy (like, 7 or 8), my uncle, of Canadian descent, had me totally convinced that Americans measured time in Bushels and Pecks instead of Hours and Minutes. :-S

Noooooo! Hours are hogs heads and minutes are furlongs. Bushels and pecks are micro and nano seconds respectively.

nolaegghead · December 2012

You're thinking of firkins and rundlets. Volume units.

Skiddymarker · December 2012

nolaegghead said:

You're thinking of firkins and rundlets. Volume units.

I stand corrected....

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Discrepency in Temps - Maverick ET-732 chamber probe vs BGE inbuilt thermometer.

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