UDS temp control Cant get it below 250

Discussion in 'UDS Builds' started by ghilljr, Apr 14, 2013.

  1. Hello ,I just finished my uds This is the first one i have build. Im in the seasoning stage. .i am having temperature control problems.I have a standard open top drum with a Weber lid .It fits well.I installed   three 3/4 intakes ,two with caps the other with a ball valve with 30 " extension.All have been RTV high temp sealed around the outside.My coal basket is 15" across by 12 inchs deep.with 3" feet. made of mesh. I started using the minion method with 10 coals.with about 10 pounds of unlit.I'm  using Kingsford Oringinal .I started the 10 coals in a chimney , let ash over.Then i dumped them in the center. I put on the lid ,All temps was taken with the lid thermo,until i get my other one in.  I capped the first valve at 190. then the second at 210. and closed the ball valve to half.The temp keep climbing. After about 30 minutes the temp settled at 260. So i closed the ball valve a little, Waited 30 minutes. The temp never moved . So i closed some move , Waited checked again , went down a little. repeated to try and get the temp down to 225 . with everything closed the temps riding at 250 steady for 2 hours.The thermometer are calibrated with boiling water.  I need to get the temps down , i don't know what else to do . I post pictures in a few.Any suggestions .  Thanks Sam
    daveomak likes this.
  2. Hers are the pics

  3. dward51

    dward51 Master of the Pit OTBS Member

    Sound like you have an air leak somewhere. What is the temp rating on that red RTV?  Those joints are pretty close to the fire basket. Once charcoal is lit, it does not take much air to keep it going steady.  This is why UDS and WSM smokers work so great.

    Try starting the capping about 10 to 20* earlier on each of the other two inlets and crank the ball valve down to 1/4 open.  As you found out it takes a while for a fire to be choked down once it's up and running.  If it stalls, just crack the ball valve open slightly a little at a time.  It's easier to creep up on a temperature than it is to choke it down.
    Last edited: Apr 14, 2013
  4. Thanks i"ll check for leaks.  Im going to try a smoke tomorrow, Ill cap off earlier . and see what happens.
  5. Ghilljr as was stated you may have a leak at your air inlet, however looking at your drum you have a lot of leakage from grease or tar from heavy smoke. Whatever the case is, it is a sign that you lid does not have a tight fit. For a UDS to perform at its peak it must be air tight. Some builders cut the rim off the drum head to make the weber or a clone lid fit. To each his own but I feel this destroys the integrity of the drum. Most drums are 23" and the Weber lid is 22.5"; you only need 1/4" to make the lid fit. I feel it is easier for me to rework the lid than cut the barrel an weaken its form.

    This is how I rework the Weber lid to get a tight fit. I hold the lid with the edge against a hard surface and using a hammer on the inside rim, I start to flattened it out. Once I have the rim flattened, I put it back on the durm and center it. It is sometimes good to have an extra hand when you start to bend the edge back down. I align the vent on the lid with the ball valve as a point of reference so that when the lid is replaced in future use, it is always in the same position.

    I begin by crimping the lid's edge back down with the hammer. I bend it enough so that it will hold as I go to the oposite side and do the same. I do this all the way around the the drum, crimping the lid on oposite sides until the whole lid is crimped with a snug fit. If you make it to tight it may be difficult to remove when the metal expands. If this happens just tap the edge of the lid back out until it is a snug fit.

    Once I close the ball valve and the lid vent, the fire is usually out in about 20 minutes and the drum is cold. My drums are so tight that the slightest movement of the lever (open or close) on the ball valve will raise or lower the temperature of the drum by single degrees. I believe the more drums you build, the better your construction will become and the better your UDS will perform. I hope this helps.  
  6. As i was looking back at the pictures , i see what your saying. What i did was add strip of 1/8  aluminum around the inside lip of the drum . Then tweaked it a little. i kept the aluminum up a little high for that reason.Should i move it down  so the Webber lid sits a closer to the drum?.  , I have no side to side movement or rocking in the lid.Should i just scrap the aluminum and bend her to fit? I did oil the lid and sides pretty heavy.The pictures was taken after i just oiled it.

      sorry DWARD51 i missed the question about the RTV ,600 degrees continuous. IS that temp ok?
    Last edited: Apr 15, 2013
  7. dward51

    dward51 Master of the Pit OTBS Member

     I would expect the heat that close to your charcoal basket to be higher than that.  Especially when the charcoal is freshly lit.  Do a good close inspection and see if it has gotten hard, brittle or burned in any areas.   Most UDS builders weld the pipe nipples on the drum.
  8. I checked the RTV , not brittle at all. It's only on  the outside of the drum,nothing on the inside. I threaded the nipples into the drum then screwed conduit nuts on both sides.There is a nice tight fit. I only added to try and make it as airtight as possible. I filled the drum with 6 inchs of water today, no leaks from the intakes. I did a close inspection of the aluminum and i can see some air gaps where there connect . nothing real bad. Can i use stove door gasket there ? or is there another method im not thinking of.
  9. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Sam, morning.....  On the next smoke, try capping the 2 inlets at 150 and closing the valve down to 1/2 open... be sure the lid vent is wide open when you start up and leave it open during the cook....   add the meat...   without meat in the UDS, there is little to absorb the heat.... meat should help cool the temps...   sounds like the lid fits well.... some folks have rtv'd stove gasket rope to the inside of the lid groove to help seal it.... Like others have said, a small air leak will keep a UDS cooking right along...  If you close the air exhaust on the lid, there should be no smoke escaping around the lid, or maybe a very, very small amount.... that is a good check....  by the way the UDS holds temp for a long time, I think the temps just got too high at the start.....  

    BTW, an excellent description of what you were doing, and how the smoker was started, to help us, help you, in trying to figure out stuff..

    Last edited: Apr 17, 2013
  10. bruno994

    bruno994 Master of the Pit

    I would also add that 250 is really not that high, I cook everything at 250.  You won't notice much if any difference in your product at 250 as opposed to 225.  I'm with Dave, maybe the temp got too high before you started capping the inlets off.
  11. Thanks guys, ya'll nailed it. She is chugging right along now at 225. I wasn't closing the intakes early enough .I closed them at 150 and the ball valve to under half, After the temp  settled, i slowly brought  the temp up. I also sealed around the aluminum strip on top of the drum. No leaks.Now i need to get it painted , and cooking some pork Thanks all Sam
  12. so ms smoker

    so ms smoker Master of the Pit Group Lead OTBS Member

      Good job Ghilljr ! Now looking for the q-view!

  13. Thanks hopefully this weekend.
  14. At the 3 hour mark, sorry no finished pics .didnt last long enough to take any lol

    thanks everybody for the help.
  15. fwismoker

    fwismoker Master of the Pit

    Besides the air thing....a water pan will keep the temp stable. 
    Last edited: Apr 20, 2013

Share This Page