I need some help understanding temperature readings

Discussion in 'UDS Builds' started by rugsrme, Nov 5, 2010.

  1. rugsrme

    rugsrme Fire Starter

    Ok, I'm seasoning my new UDS, I have the dial thermometer mounted just under the upper rack. I also used a digital thermometer putting the probe through some holes on either side of the lid, the holes were from some sort of rack in the old uni-flame kettle grill.

    Any way, the temp seems to be pretty stable except when I'm playing around opening and closing the pipes and the ball valve.

    However, the dial therm. was reading 180, and the digital would read 236 on one side, 190 on the other and when I dropped the probe down the middle of the vent on top it would read 150 or so.  Why am I getting all these different temps??????

    I checked the coals and they seemed to be burning more on one side than the other, but when I closed a pipe and opened one on the other side of the drum it didn't seem to make any difference.  There was a slight breeze early on and it is pretty calm now. (I used the minnion method to start my coals, I think I did about right because the temp went right up and held without going too high or dropping unless I was messing with the intakes).

    Since I am using a water pan, is the average nominal temperature probably around 220 ish?

    The last time I was out, I pulled off some country style ribs that cooked ok, and left the probe in a fattie and it is gradually working upwards now it is at 133.  I'll know in another hr or so if they are going to get to 160 before I pull them off.


    Last edited: Nov 5, 2010
  2. eman

    eman Smoking Guru Staff Member Moderator OTBS Member

    Not being a uds owner i can't give you str8 answers. But a 46 ° shift from one side to the other seems extreme to me.
  3. deannc

    deannc Master of the Pit

    I've never used a water pan in the uds so I may not be much help.  The uds usually creates so much humidity I pour out moisture from the bottom of the drum after a long smoke so I haven't seen a need for a water pan.

    For making temp adjustments, give it 15 minutes after making an adjustment. Once you reach the temp your shooting for after start up, you really won't need to make many adjustments. If you can't get the temp above 220*, give it some more air.  When mine does drop slightly below 225* I'm usually running at 1/2 throttle on the valve and if mine were to drop to 220* I'd unscrew one cap until the temp rises back to 223* or 224* and then put the cap back on and she usually settles right back in at 225*.

    How high off the bottom of the drum is your coal grate?
    Last edited: Nov 5, 2010
  4. meateater

    meateater Smoking Guru SMF Premier Member

    Coals burning on one side will make a difference a well as the wind. I started with one exhaust on mine in the back and figured out the heat was going towards that vent and added two more to make a triangle. Water pan and 220 is about right. Just make sure your therms are accurate, The ones mounted on my drum I only use for reference. I have a couple of digitals I use for meat only. That's just the way I do it, keep on smoking and taking notes untill you dial it in. [​IMG]
  5. rugsrme

    rugsrme Fire Starter

    I think I'm going to quit using the water pan the next few times, and it made me rethink how I want to set up my coalll grate.  It sits 3" of the bottom, but I have it sitting in a bowl with about 2 1/2 " clearance from the bottom of the bowl.

    I think it is not allowing the most efficient O2 flow to the coals so I'm going to put legs on it.

    Since I took the water pan out it has been sitting at 250 with 3 caps on and the valve open.

    I makes sense too that the temp would be more on one side if the coals are burning uneven the water pan was diverting heat straight up from the hotter coals.

    Thanks for your help all.
  6. meateater

    meateater Smoking Guru SMF Premier Member

    I'm thinking we need a reference as to state location and humidity as far a  UDS. Months will be needed as well.
  7. rugsrme

    rugsrme Fire Starter

    Hmmm I never thought about that, I never smoked anything when I lived in Henderson, but I'm sure the humidity makes a big difference, we had 42% I suppose the water pan may be required.
  8. deannc

    deannc Master of the Pit

    There are about as many ways to set up a fire basket as there are ways to smoke something! lol  Below is how I set mine up using a $3 pizza pan from Wally World.  I got the idea from someone on here who has posted something similar.  Not sure what diameter etc that your basket is, just thought I'd post the picture to give you an idea of one of the many ways to set it up.


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