first cook wont hold cook temp sm26

Hey guys/girls, I have recently purchased an sm 26 cookshack smoker for my bier cafe in Mornington, Victoria Australia. I did my first cook today with some problems which I will outline below and would certainly appreciate your help and feedback.

First cook:

one 6 kilo brisket (12pounds)
cooked on the probe setting with the probe temp set to 185f. Hold temp set at 165f and the cook temp set at 225f.

I loaded both wood boxes with a total amount of around 11 – 12 ounces – approx 320g in total of hickory chips. They are chips not chunks and not the small beech wood that came with the oven.

I did make the mistake of putting the wood in first and when it started to smoke I opened the oven to put the brisket in and of course the wood caught fire! Lesson learnt!! I quickly removed the wood boxes threw the wood in the sink and wet it so no crisis. Dried the wood boxes and refilled with the same amount of wood chips.

I put the brisket into the oven on the second shelf above the hood, put the wood chips in and closed the oven. I reset the settings as per above and pressed start. For the next six and a half hours the oven did not hit or stay on the cooking temp of 225f which I set. It sat at 259 – 265f.

I eventually called the Australian distributor in Sydney (Smo-king) and talked with them about it. They suggested I turn the cook temp down which I did to 210 and over a period of 15 minutes the oven temp dropped to 236. When I turned the oven back to 225 the oven shot back up to and sat at around 251 – 259.

After about 5 1/2 hours when the meat probe was at 183 I opened the oven and removed the smoke boxes as the sydney people thought perhaps it was contributing to the heat. There was only ash in the boxes no coals, no charcoal and no real heat as I could hold my hand very close over the boxes with no discomfort at all.

The door was open for several minutes , when I closed the door the oven temp was 208f. I reset the cook temp - 225, probe temp - 185 and hold temp - 165 and pressed start. The oven temp rose steadily right back to 259 – 263f and stayed there.

I turned the cook temp down to 200 and the oven temp dropped down to 230 and when I ajusted the cook temp to 225 it went back and stayed at 259 – 263 until I eventually turned it off and removed the brisket.

After the oven had been off for some time I turned it on again and it read that the oven temp was 100f. I set a cook temp at 150 and a cook time for 4 hours. The oven was empty. The temperature rose past 150 until it reached 193 – 195f where it stayed until I turned it off.

I hope I am doing something quite obviously wrong........but it is my understanding that if you set an oven temp to cook at it should sit at that temperature for the duration of the cook? The fact that the oven sat at the highest setting it is designed to go is of great concern. If I change the temp for the cook I would expect the oven to reflect that? This was backed up by John and Vicki at Smo’kingovens.

John has suggested i do another cook and see if it works but that was on the basis that I may have overloaded the smoke boxes. I filled them 3/4 full with the chips, I have since weighed the amount of chips I used and I can absolutely guarantee that the weight was between 11 – 12 ounces in total so I see no need to do another cook.

Could the calibration for the temp controller be out by 45 degrees f ie cook temp set at 225 but oven temp sat at 263?? cook temp set at 150 but oven temp sat at 193? as examples above.

Could the thermostat be broken? Has anyone else experienced something like this?

I look forward to some guidance.