Masterbuilt XL thermostat control mod

Discussion in 'Propane Smokers' started by spoolinaz, Aug 3, 2012.

  1. spoolinaz

    spoolinaz Meat Mopper

    I've been wanting to do this for awhile now. I've already converted it to natural gas, so that part of the job is done. I was going to go the way of the pilot light like others have documented, but didn't make me comfortable. I have had ALOT of problems with the flame going out on the stock XL burner. A system with a safety valve makes this much safer.

    Started by searching for a cheap used gas oven on CL. I founf a 10 yr old GE missing a door for $30. SCORE! Only problem after hooking it up was that the igniter was shot. So out of pocket for another 25. So $55 in and I have all the components to make my smoker 'set and forget'. The system runs on 110V, but my smoker is stationary, and I have outdoor power right next to it. The thermostat should go from 150 to 500. Thats a better low end than you can get on a stock XL for sure.

    Decided to use the burner bar for the gas oven as well. Makes for alot less fabrication. So last night I got started by power washing the XL and tearing out the stock burner and components.

    Laid out some cut lines on the bottom for where the new burner would live. Got out the cut off and went to town.

    I used the stock burner bar mounting hole on the one end and fabbed a steel bracket on the other end. The bar only sticks down 5" or so, so there was plenty of clearance underneath the smoker for all the components to live.




    With the burner/valve assembly mounted, It was time to consider a wind break. After a quick check, the stock XL burner mount covered all of the burner holes, So with a quick trim for the igniter, I bolted her back up. I will more than likely trim the height down after I get all of my fitting done before final re-assembly. I also need to address the huge hole in the bottom where all of the un-captured drippings can fall through and stain my deck (even more).

    I luckily found a perfectly sized piece of heavy steel channel to use as the burner bar cover. This will give me some mass to help distribute heat evenly, and a place to set the wood chunks for smoking. I will hold onto the cast iron pan for now, but may not be necessary. I am going to install a height adjustment system for the channel so I can keep the wood burning at the right temp, no matter what temp I'm smoking at.

    That's my progress for now, hope to finish it up this weekend. I have some Bearcarver dried beef in the fridge waiting to be finished!
  2. pops6927

    pops6927 Smoking Guru Staff Member Moderator Group Lead OTBS Member SMF Premier Member

    Great tutorial! 
  3. spoolinaz

    spoolinaz Meat Mopper

    Well, I got her all finished up. Had to go shopping for the gas fittings and electrical. Mounted the thermostat in a water tight box. Mounted it in the same location as the stock knob.

    Then I plumbed the gas line side.

    I decided to do an adjustable height system with knobs through the side of the cabinet. The knobs should be in today.

    She fired right up on the test run! Only problem I encountered was that the smoker temp was about 100 degrees off between the thermostat and my 732. Think it might have to do with the thermo bulb running outside the smoker. Going to try moving it inside and try again. Also, I didn't use the oven's pressure regulator, so the burner puts out alot of flame. I will try to regulate this with the ball valve shutoff I have inline. Still a little trial and error to work through, but I'll get it there!

  4. spoolinaz

    spoolinaz Meat Mopper

    I made some adjustments this weekend smoking some ABT's, turkey thighs and potatoes. I moved the entire thermostat bulb and tube inside the smoker hoping it would help the huge temp difference between the dial and actual. It did help some, but was still nearly 75 degrees off. The knob I have has an adjustment on it to account for this difference. The adjustment amount wasn't enough, so I modified it by elongating the slots and got it pretty close.

    I also turned the flame back by closing the gas valve partially closed. This did the trick. The flame was on much more than it was off to control the temp. Whereas before it woiuld come on for a min or 2 and turn off. This was causing huge spikes and drops in temperature. By turning the flame down, it allows the heating to happen slower and thereby being more steady. The temps swings I had yesterday were about 15-20 degrees between on and off. I could add more mass inside or insulate to get this better yet, but I'm happy with that result. We'll see what cold weather smoking brings to the table.

    The wood "bar' and adjustment system work well. Had it set to just smoldering yesterday. When I lowered it the wood soon got too hot and caught on fire. I will have to play with it some more to find out where it needs to be in relation to the temp I have set.

    This mod overall has been a very good one. I now have a mechanism to control the upper and lower end of the temp swings. Also, I now have a safety valve that will prvent flame blowout, and turning my smoker into a bomb!
  5. shoneyboy

    shoneyboy Master of the Pit OTBS Member


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