Portable Digital Propane UDS

Discussion in 'UDS Builds' started by hobbyfarmer53, May 17, 2016.

  1. Converted my UDS to a portable digital propane UDS.   My UDS has been used for about 4 years.   I used a PID to control a fan to control the temperature.   This worked great for long smokes.   You could set the temp and leave.   The problem was when I had smokes where I had to open the smoker to baste or whatever.   When I opened it I just dumped in 55 gal of air and the temp would spike 50 – 80 degrees and take about ½ hour to re stabilize.

    What I did was put in a 40K BTU cast burner and use my AMNPS to provide the smoke.   The pilot light for the burner powers a thermopile which in turn powers a millivolt gas valve.   I use the PID in on off mode as a thermostat to control the gas valve.  

    On my test run it worked great except it cycled too fast for my liking so I built a frame to sit above the burner and AMNPS.   On that frame I put a stainless fry pan filled with sand to provide a buffer between the flame and meat and to create a heat sink to lengthen the cycles.   I also lay a piece of steel over the AMNPS to prevent drippings from falling on the pellets.

    I wanted to keep it portable so I put a quick disconnect on the gas valve because I want to take it to the races at Knoxville this summer.

    Hope to try it out this weekend for it’s maiden run.

    Lid and door of control box off for picture

    Burner and AMNPS are raised off the floor about 2 inches to keep them out of the sludge

    Pan for sand and cover over AMNPS.  Also shows temp probe inserted so it reads from center of smoker right below the rack.
  2. tjohnson

    tjohnson Smoking Guru Staff Member Moderator Insider OTBS Member SMF Premier Member

    I like the concept, but wonder if there's enough air for combustion of the pellets???

    The flame may use up any oxygen needed for the pellets

    Adding too much air could throw off temps too

    It's really gonna be a "Trial and Error" thing to get this right

  3. I have 3 1 inch holes available for outside air from the original UDS setup, and the burner is fed by an outside venturi so I am hoping between the combination I will have enough oxygen.  I guess the only way to find out is to try it.  Thanks for your input!
  4. Todd was right.  The propane sucked up too much oxygen so I will have to put the AMNPS in it's own compartment.  The pid and thermopile run gas valve worked great.  With a pan of sand it would cycle about once a minute.

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