Unstable temps and a question about thermocouples


Michael CS

New member
Hey all, first post with my new 4.3.3 HM Christmas present. Assembly and configuration went swimmingly.

First, a question about thermocouples - my two TW probes are within a degree of each other, which is a fine tolerance for me, and those two probes are within a couple degrees of this thermocouple I got off of amazon after seeing it recommended a couple times here. This is after doing the boiling water calibration. However, when around room temp, there's a variance of about 10 degrees between the probes (which I think are the more accurate) and the thermocouple probe. Is this normal to have that big of a difference? I know the boiling water is close to where my temp will be most of the time, so I'm not that worried, but I thought I'd ask. I've checked the board for shorts or missing resistors and haven't seen anything strange.

Second, I did a practice burn today to test out the HM before doing a pork shoulder on Monday. I had what I think is a lot of temperature variability.

I'm cooking on a 14.5" WSM. I've only used this smoker for a couple of cooks - am I right in thinking this is too much air getting in? It's even taking forever to ramp down. Using a dogbowl setup, two vents totally closed, the one under the dogbowl closed about halfway. Admittedly, my fan/servo combo is a homebrew one with cardboard attached to the servo that closes over the top of the air input pipe, so that's not perfect, and I should be printing a microdamper in the next week or two. Any input is appreciated. If you want more detailed info it's currently running here

Thanks, excited to get some meat smoking!