Thermometer Wraparound - BGE Tip
14/01/13 Filed in: BGE Tip
I am told that many folks visiting the site these days are BGE newbies who see links to my site in my posts on the Egghead forum. I am a relative newbie myself & I had something happen the other day that I didn’t know anything about. I have since found out it is not uncommon. What I am talking about is that the stock dome thermometer on the BGE is capable of going past the highest temperature listed of 750 degrees. It turns out the long time users on the Egghead forum call it Thermometer Wraparound.
Look at the picture at the top of this entry. What temperature is the thermometer reading? Well I can tell you this was late August and the air temp was in the high 80’s (30 C). But as I found out that reading could also represent 800 degrees or so. You see the BGE thermometer has no stops on it that prevent the needle from traveling above or below a certain point. Your probably wondering how you can let it get that high without noticing. Well it is easier than you may think if you aren’t careful. I will give you my example. I was cooking pizza on a 20 degree night (-7 C) and I had the Egg warming up to 600 degrees (316 C) while I was in the house prepping the toppings. I usually try to check on the Egg when it should be around 500 degrees (260 C). I don’t use the top Dual Function Metal Cap for cooking temps about 500 degrees (260 C), so at the 500 degree mark (260 C) I start closing down the lower Draft Door to coast up to 600 degrees (316 C). I decided to delay going out by 5 minutes because I had put a plate setter & pizza stone on that was at the 20 degree (-7 C) air temperature. I figured this would make things take a bit longer, so I delayed my trip out to check on the grill by 5 minutes.
When I heeded out to the grill I was greeted by a grill that was not at 500 degrees (260 C) like I expected, but was at the exact same temperature as when I started. It hadn’t moved a bit. I was thoroughly confused. I flicked the thermo with my finger to see if it was stuck and my theory was where this was the second time I used this grill, maybe the thermometer was defective. I decided to give it 5 minutes more to see what would happen. When I returned the temperature was now reading about 150 degrees (66 C) right where the lower end readings on the gauge start. I decided my bad thermometer theory was indeed what was happening. I decided to check the fire to see if it had gone out. I touched the side of the dome and to my great surprise it was screaming hot. I double burped the lid to avoid a flashback and found I had a roaring fire inside. Still thinking I had a thermometer problem, I closed the lid and closed the bottom Draft Door to bring the temperature down because I could tell it was way too hot. The temperature started dropping fairly rapidly and it soon dropped past 750 degrees (400 C) where the high end of the temperature scale on the gauge started. Soon it was at 700 (370) and still dropping and that is when light dawned on Marble Head. The temperature gauge had been working correctly all along. When I went out later than normal, the temperature had shot past 500, 600, 700 (260, 316, 370 C) and had gone off the scale. Until this moment, I didn’t know that the temperature would go above the highest reading on the scale and wrap around and start taking a second lap around the gauge.
So the lesson to be learned here is: Keep a close eye on your Egg. When there is no top cap on and the lower Draft Door is wide open, the BGE can all of a sudden pick up a huge head of steam and start rapidly climbing. If you suspect the temperature gauge may have wrapped around there are two things to check. First carefully touch the side of the dome. et me stress the word carefully. If it is scaldingly hot the gauge has probably wrapped around. The second is to check the fire. Be sure to double burp the lid. Lift the lid 1” (2.5 cm) and pause for a few seconds. Then lift the lid to 6” (15 cm) and pause. Then lift the lid. Trust me you don’t want a flashback/backdraft. If the coals are all lit and roaring away, you have wrapped around your temperature gauge. Close things down and get the Egg back to your desired cooking temperature. If you are using a plate setter or pizza stone give them some time back at the desired cooking temperature before putting your food on. Where they are ceramic it will take 15 minutes or more for them to give off all of their excess heat.