The trick is to smoke the meat and not make the meat smoke

Temperature Probe Issues

First Image
I am afraid I have Egg on my face. Not Big Green Egg, but my problem did occur when I was using the Big Green Egg to cook my Standing Rib Roast low and slow. The problem was definitely not with the Egg, but with the user of the Egg-Me. I figured I’d post the cause and effects of my problem, so that other Egg users won’t make the same mistake. The problem I created could also happen in similar but different ways on other grills too, so it might be worth a read even if you don’t own a Big Green Egg.

When I fired up my Large BGE to cook my roast I added 3 paraffin starters spread out 120 degrees apart and lit them about 30 minutes before I wanted to start cooking. After the paraffin starters had burned for about 5 minutes, I donned some BBQ gloves and added the plate setter, legs up, and I installed the stainless steel grill grate. Then I installed the grate probe for my Maverick ET-732 remote read thermometer. It has a metal clip that holds the probe up about 3/4” (2 cm) off the surface of the grill grate and secures it to the grate. I placed it about 2” (5 cm) away from the front lip of the grill. I wanted it to be in a bit from the gasket, without being in so far that it would interfere with the placement of the cast iron drip pan I was using for the roast. I was planning on using the grate thermometer for the temperature readings as opposed to the dome thermometer. I expected the dome thermometer would start out quite a bit different from the grate thermometer but after 30 minutes or at most and hour it would eventually move closer to the reading of the grate thermometer. At least that had been my experience doing low and slows when I first bought my Egg.


This is a shot of the Egg this day as I had just installed the plate setter legs up and put the stainless steel grill grate on the plate setter . You can see the three open areas (where the visible glow is) which allows you to do a combination of indirect grilling & convection. My problem came when I installed the probe over the open are in the front as you will see in the pictures below.

It had been about 3 months since I had done a low and slow and the air temps were about 60 degrees (33 C) lower this day than in the summer. But my experience to date is the Egg seemed to perform about the same despite the weather. I fully expected this experience to continue this day too. But strangely enough it didn’t. The dome temp was quite low when the grate temp hit 225 degrees (110 C), so before I put the meat on, I let the temps rise until the dome was 225 (110 C). But at this point the grate temperature was now 295 F (146 C). This was odd because I’d checked the thermometers for accuracy using boiling water and they were very close to one another. I was hoping the temperatures would even out a little bit and get closer to each other. I was wondering if the blast of cold air from opening the lid to add the meat, plus the cold piece of meat were responsible. The meat had been out for 2 hours, but the internal temperature was still 45 F (7 C). I let the temps drop a bit. I hoped the grate temperature would fall more than the dome temp as the ceramics in the dome absorbed the heat. Sadly this was not to be. The grate temps initially fell back, but so did the dome. I was suddenly looking at a 180 degree (82 C) dome temp and the grate temp began rising while the dome did not. This was a problem. I was concerned that since the meat was up inside the dome, the dome temperature probably had the most relevancy, so 180 degrees (82 C) wasn’t going to cut it.


The whole problem was caused because I had installed the remote read grate probe over the opening in the plate setter exposing the probe to direct radiant heat from the coals. (left). This picture is an enlargement of the picture on the left and you can clearly see the probe is close to the outer edge and over one of the three openings in the plate setter. (right).

Plus based on previous cooking logs for this meat when cooked under similar conditions, I was falling behind on my internal temps and the cook was going to take far longer than I’d planned. At this point I was midway through the cook and I decided to let the temps slowly rise so I could get back on track. I decided I would let the temps rise to a maximum of 350 F (175 C) on either thermometer. This is the temperature that folks cooking this roast at high temps use. I really needed to get myself back on track and logic seemed to be out the window this day. I mean how do I explain the temps remaining so far apart and eventually the grate temperature rising while the dome temp remained constant? It was cold, but it wasn’t that cold. I only opened the lid once during the cook to add some wood chunks onto the fire. So I let the temps rise slowly upward and at the end I was looking at a maximum grate temperature of 335 (170 C).

The roast took nearly 90 minutes more than planned despite my cooking it at a higher temperature for half the time. Fortunately the roast turned out to be excellent. It was tender moist and juicy, no doubt due to the superior seal of the Egg, which helps retain moisture. This was my best standing rib roast ever, and I could only imagine how it would have been if I was fighting temperature weirdness. So what caused it? I was still no closer to finding out and so I posed the question to the brain trust at the Egghead forum. I posed the question as if it was a cold weather problem. I made a separate picture post of my roast and some one who saw both posts said my remote temperature probe on the grate appeared to be over the gap in the plate setter and was therefor exposed to direct, not indirect, heat. You see the plate setter has three crescent shaped gaps around the perimeter which serve to create a convection effect around the perimeter of the grill. My probe was indeed over one of these gaps and was therefor subject to direct radiant heat as well as the radiant heat from the coals below. This certainly explained the problem and explained how the grate temperatures could rise, while the dome temps fell. In case you aren’t familiar with radiant heat, it is a form of heat gain where warm temperatures are passed off from a warm object to a cooler object without heating the air in between. Think of sitting in a cold car on a cold day and you get hot from the direct sun streaming in through the window of the car. The air is still cold but you can get quite hot. In this case the temperature probe was measuring both the air temperature inside the Egg at the grate level and radiant heat from the charcoal impacting on the surface of the temperature probe.

Now everything makes sense again. My thanks to the folks on the Egghead forum who determined my problem from the pictures I posted. So bottom line if you are doing an indirect cook, like I was attempting here, make sure that you temperature probe is only exposed to indirect heat. There shouldn’t be an open line of site between the probe and the coals.


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