New smoker - Help needed with troubleshooting

[ledhead84]

I'm in the home stretch of my smoker build (link below) i cleaned it up today and attempted to season it. I was not able to get the temp's above 220.

http://www.smokingmeatforums.com/forum/thread/103584/mini-patio-rf-build

I started with a full chimney of lump (cheap Blue Bag Royal Oak...didn't want to waste my good stuff) left the air inlet wide open and the chimney baffle wide open. It climbed to 150 in a half hour or so, i left it and came back and an hour later and it was only at 200, i added some more lump and the temperature still would not climb. 

I am thinking that i am getting too much air coming in around the cook chamber door, there is a bit of a gap from some welding warp. I had another open hole on the side i left for temperature probes, i plugged that up and the temp got up to 220. Whats the best to use to seal up the door better, are there any products like high temp silicone that would be safe to use?

http://www.imperialgroup.ca/fireplace_maintenanceproducts.cfm?c=385   I can pick this up local or would i better be using fire rope?

If it is not the door where should i look next?

 

[texasburner]

I wonder if you are not getting enough flow out of your exhaust to create sufficient draw. I know you said it raises up a inch or so but I wonder if it needs to go higher.

I am by no means a pro, just throwing out ideas.

 

[bmudd14474]

It looks like you have set it so that the connection between the firebox and the tank is extremely small. If this is too small it will constrict the air flow causing you not to get enough flow to allow the fire to burn hotter. 

 

[ledhead84]

I wonder if you are not getting enough flow out of your exhaust to create sufficient draw. I know you said it raises up a inch or so but I wonder if it needs to go higher.

I am by no means a pro, just throwing out ideas.

The baffle on the chimney swings right out of the way so it won't restrict the flow.

It looks like you have set it so that the connection between the firebox and the tank is extremely small. If this is too small it will constrict the air flow causing you not to get enough flow to allow the fire to burn hotter. 

I was thinking the same thing, i have some room to open up the fire box to cook chamber opening. There is about a half inch lip on one of the tanks, if i cut that out it should give me about 40% larger opening.

 

[tom37]

By all means, open that sucker up. 

You can always shut down the fire with the damper on the firebox door. 

The silicone you linked to will work fine. But the silicone with the rope will work better. 

On my first couple builds I used the silicone only. What I did was lay down a big oll fat bead. Then I took blue paint tape and very lightly applied it to the top of the silicone bead. Then I slowly lowered the door to the point where I could let go of it. I checked to see that all the gaps where now gone. Raised the door and let it all dry. Once dry the tape will peel off the silicone with ease. If it all goes good you should be able to shut the door and latch it, offering that little bit of extra cinch to totally seal the door.

Now I lay a small bead and stick the fire rope to that and once again shut the door once without latching it, then open and wait to dry. 

Good luck and let us know how it goes.

 

[ledhead84]

Thanks for the input guys,

I was thinking about it and i think i left the drain for the grease trap open when i was seasoning, is it possible that it that could have been sucking cold air right into the cook chamber.

Here's the game plan, open up the firebox to cook chamber opening as much as i can, get the door sealed up, and do another test burn (with the drain closed).

If that doesn't work I'll have to do some surgery and add an air duct to the bottom of the cook chamber to allow for more air flow.

 

[Fife]

Hope you are able to get it going.

 

[ledhead84]

The more I look at it the more I think my design for the RF plate is choking off air flow where the angles meet at the drain. I tried to make the RF plate as low as possible so I had more cooking space available, but I think I overlooked how much I cut into the space under the plate.

I am thinking about taking more drastic measures to improve flow. My idea is to cut a 5”ish wide slot in the bottom of the cook chamber underneath the RF plate then welding up a channel piece to hang below that opens up into the fire box and extends to the other side of the plate, this should almost double the area to allow for a lot better flow.

My question now is can I make that area too big? Or will it not matter since I can always choke down the damper on the air inlet in the fire box?

 

[ledhead84]

Got the patient up on the table ready to do some abdominal surgery...to help her breath better. Broke out my scalpel (plasma cutter) and cut out about a 6” strip from under the RF plate.

I believe this was causing me issues, I had a 10ish sq inch opening at the fire box, and then my RF plate design choked it off to about 5 sq inches in this area.

I used some 1” flat to build up around the edges of my cuts then plated the bottom. At the smallest section where the drain is I now about a little less than 12 sq inches, should more than double the area.

Might be hard to see, this is from inside the firebox looking under the RF plate (made the opening from fire box to cook chamber bigger too, Excuse the messy cut, was hard to get the plasma torch in there).  Now I have a nice open run from the fire box to the end of the RF plate with no bottle necks. While I was at it I also trimmed the end of the RF plate to make sure there was lots of room for smoke to travel.

Hopefully i will get some time to do another test burn on the weekend and see if that did the trick

 

[ledhead84]

Still no luck! did another test burn after work today, temps got up to about 150 at the grate and wouldn't go higher, i cracked open the fire box door and they shot up pretty quick to 220-230....so now i thinking fire box inlet too small? or is my design/fire box just too small to be functional,

I'm starting to get disappointed

....I'm about ready to scrap it and buy and Weber Smokey Mountain........

 

[daveomak]

First you might try adding 1 or 2 feet to the chimney with sheet metal to see if the increased draw from the exhaust will solve your problem. If it works cool.

There is an equation somewhere on chimney height vs pressure change that explains why chimneys work. A chimney will draw air at a given height. No need for heat. It has to do with atmospheric pressure differential vs altitude. I read that somewhere.

I built wood stoves for tents for awhile. I know 6 ft of stove pipe and the stove would not draw. 8 ft and it worked perfect. No other changes needed.

If the stack extension works, you can make it removeable if necessary.

Hope you find a solution 'cause your smoker is cool. Don't give up. There are no mistakes only valuable learning experiences. Dave

 

[ledhead84]

^ thanks for the tip, i'll give that a try before i break out the plasma cutter again

I have a Chimney Full getting ready right now and a 1 foot HD aluminum foil exhaust extension. Third time's a charm...hopefully!

 

[ledhead84]

With the chimney extension, air inlet wide open got up to 230 at the grate and holding steady after an hour, i cracked open the fire box door 1/2" and the temp started to climb and leveled out at 239!, I'll be happy when i can get 300+

Next step i think is going to be a bigger air inlet, and maybe add some volume to the fire box the same was as i opened up the area under the RF plate, the picture on the left is how it is right now and the right is what i am thinking of doing. So allow for a lot more air to flow the length of the fire box

 

[slimtony1974]

I have been following your build closely!! I am in the process of designing a similar Mini!!  What if you added a small fan to the firebox inlet?? Force some air in??  I have a Chepo wally world grill that i added a small computer fan to to get a little more air and the temp jumped up!!! I got the idea from a Stump Smoker..

just my $.02!!! 

 

[ledhead84]

I would be worried about creating an ash storm that would blow around and into the cooking area with an electric fan, hopefully i can get enough air flow with some more modifications.

 

[ledhead84]

4th times a charm?

Back up on the table for some more surgery, cut 3" strip out of the bottom of the fire box and welded on a piece of channel i had left over from another project.

Lots of room for air to flow under the charcoal basket now...and more room to collect ash for long burns

 

[tom37]

Looking good, I really like the looks with the channel on the firebox.

 

[ledhead84]

After an hour and a half just topped out at 270! At least I'm getting some usable temps now, just need some more time with it to see how well i can control the temps....but feeling better about it today.

 

[slimtony1974]

Updates??

 

[wildrooster]

what was the average temp out side when you fired your smoker ?? out side temperature will affect performance.

if you want to smoke in the winter you will need much more heat .

I would try a slider to let more air in or try some wood if you have the room