Low Temps - Have Idea - Need Advice

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Ringer

Smoking Fanatic
Original poster
SMF Premier Member
Sep 10, 2019
740
693
Chickamauga, GA
Good morning all, I have run a couple of smokes through my new reverse flow build. A little background: I built a 3' x 6' cylinder reverse flow. The firebox is big as well coming in at 36" long x 30" tall x 24" deep.

I noticed on the last smoke that I couldnt get the fire up past 200. I thought about it for a minute and came up with this. On the last smoke I built a fire but it wasnt gigantic. It is hard to cover a grate that large entirely with a bed of coals. There are some gaps in front of and behind the grate and all around the fire. Air could flow straight through an area without coals and the smoker would essentially be pulling cold air through without ever making the fire hotter. I was thinking about covering up the edges and the area on the grate where there isnt usually a fire to force the air to flow past the coals as it should. I included a picture to illustrate my idea. The red area is the grate, the blue area is the fire area, the green thing is a piece of 1/4" steel cut to fit and sits on top of the grate.

Am I on to a legitimate problem here or do I just need to man up and build a fire that covers the grate entirely?
 

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  • grate cover.jpg
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Pictures of the FB inlets and wood grate height and FB/CC opening would help....
The lower air inlet should feed the fire....

Smoker Exh and Intakes 2.jpg
 
The lower opening is 3x12 inches. Technically the two dampers at the top were supposed to be at the bottom but i screwed that up royally
 
Ringer, pics are nice, but please provide a little context around the history of your smoker. How were the temps on previous cooks? Was the cooker loaded with cuts of large, cold meat before it had had a chance to stabilize? What about the ambient conditions? Cold, windy?
Type of fuel? Straight wood, charcoal, combination? A couple pics of the exhaust side would help too.
 
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Just as an experiment, can you lower / remove the grate? Inlet air for combustion should be at fire base or below. See if that will allow you to build a hotter fire. I don't use the intake vents very much to control temps. In my case I contoll temp by fire size.
I can get 275 degrees out of a small fire, no bigger than gallon of milk size wise. At least 1/2 of my fire grate is void of fire coals.
I had to play around a bit with my RF to find the right grate type/placement. Ive been 500 + degrees with a large fire
RG
 
The last fire i built i lowered the grate to where it is now. The bottom of the grate sits right at the top of the lower inlet. I can lower it more but it will sit right in front of the lower damper and may block it off.
 
Ringer, pics are nice, but please provide a little context around the history of your smoker. How were the temps on previous cooks? Was the cooker loaded with cuts of large, cold meat before it had had a chance to stabilize? What about the ambient conditions? Cold, windy?
Type of fuel? Straight wood, charcoal, combination? A couple pics of the exhaust side would help too.

Sorry i missed this.

First cook was with a large fire and 500+ was achieved. I used this as the seasoning and just added some meat on at the end. When it started dropping it dropped fast.

Second cook was abandoned because i couldnt get past 200. I lowered the grate and used a smaller fire. It was rainy and windy but not cold. I brought the fire up close to 225 then put ribs on but it dropped fast and never recovered. I started with 2 chimneys of lump hardwood charcoal and then added red oak splits. The wood was a bit damp but not bad really.

The smoker is sealed with nomex around the cc lid and fb door. The only draft comes from what i let in.
Ill attach a pic of the smoker so you can see the exhaust.
20191220_164051.jpg
 
After looking at the photos of the inside of your firebox is there room to put in some firebricks? They can usually help, and conserve fuel to. You can see them in this photo, and with this size fire we were cooking 8 or 10 butts and 4 legs of lamb. Home Depot sells the 1" thick bricks.

592kM9i.jpg

kRc8BTo.jpg
 
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Thirdeye, that is an excellent idea! I have plenty of room for that. Would the soft or hard ones be best for this application?
 
Thirdeye, that is an excellent idea! I have plenty of room for that. Would the soft or hard ones be best for this application?
I'm not familiar with the "soft" ones. The ones pictured are 5 X 9 X 1", or maybe 1-1/4. The rating is something like 2500°. I like to start with lump and cubes of flavor wood, then add briquettes during the night to keep the pit temp consistent. And for briquettes I've completely switched to Kingsford Long Burning. It's noticeably denser than the regular or Competition
 
Thanks for the tip on the briquettes. I have always used royal oak but it does burn off fast. Something with a longer burn would be fantastic.
 
That is a huge smoker... It will take LOTS of wood to keep up with the surface area that loses heat... Probably 3-4 wheel barrow loads... or more... for a 5-6 hour cook......
Try covering the CC with a welding blanket... even doubling up on the welding blanket...
You may have to get a smaller smoker for home cooks... or get a lot of fire wood... I don't think briquettes or lump will do the job.....
 
Hey Ringer, based on what you reported about previous temps, I suspect you may need to use more fuel and allow more time for the unit to stabilize before adding anything to the cc. Most of the units I have built require between 45-60 min to stabilize after the coal bed is well formed. Once the coal bed is stabilized, and cc temps have stabilized in your desired range, the shear mass of the cooker provides a buffer to help temps recover as the food warms and starts to come up to temperature.
Fire management is key, with manual dampers, you always need to stay ahead of the fire. It is far easier to slowly tame down a hot fire than trying to build one that is too small. Make small adjustments to the fb damper and then wait at least 10-15 min before making further adjustment. when it is time to add splits, do it sparingly keeping in mind the temps will probably drop until the new split comes up to temp and begins to combust. Once your dampers are set, you shouldn’t have to do much adjustment to keep things under control. Practice a bit more with what you have before making any modifications. I suspect after a few more slow and steady burns, you will start understanding the nuances and it will become easier. Good luck
 
What is the thickness of the steel on the CC.... Looks pretty thin like it was made from an oil storage tank... maybe 1/8" thick...
 
1/8" on the FB loses a bunch of heat... Try insulating it... Use a few welding blankets top and bottom... See if that helps....
 
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