Newb pit build question

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bluegrassmichael
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Newb pit build question

Postby bluegrassmichael » Sun Jun 14, 2020 1:06 pm

Hello all, I recently built a reverse flow smoker out of an 80 gallon propane tank. I put the seasoning smoke on it last night and it was difficult keeping the temp at 300 degrees also there was a 25 degree difference from end to end the fire box end being hotter. My baffle plate is an inch or so above the firebox and the other end where the heat and smoke come up is 3 inches from the end of the tank. I have a 4 inch stack 37 inches long. My firebox is 16 inches tall x 18 inches wide and 18 inches long the damper on the firebox is 2x8. was wondering if these measurements seem right. Frank Cox from smokerbuilders gave me these specs any help would be appreciated. Thanks, Michael.
strength_and_pow
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Re: Newb pit build question

Postby strength_and_pow » Sun Jun 14, 2020 6:55 pm

Welcome aboard. When you say you had problems at 300*, was it you had issues getting it to 300 or was it running away and climbing? A 25* difference side to side isn’t huge and it’s definitely something you can work with since you know it’s there. During a seasoning smoke, you will typically run hotter and be opening the doors a few times to oil it down so it may not be an accurate representation of how it performs. I’d run it again but this time at actual smoking temps and possibly even keep some notes. How much wood did you start with. How long did it take to get to temp. What were your vent positions. Make small adjustments on your airflow and give it 30-45 minutes to settle in after each adjustment. Are you using digital or analog temp gauges? Have you verified their accuracy? Some pics of your smoker would go a long way in people understanding the dimensions you listed.


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bluegrassmichael
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Re: Newb pit build question

Postby bluegrassmichael » Sun Jun 14, 2020 8:25 pm

Thanks strength, It was a little hard getting it to 300 and hard keeping it there. the 25 degree difference im ok with, that could be handy from time to time. i'll do like ya said and run another smoke at what i typically smoke at but i do like to do chickens at 300 for a couple hours. it seemed like i used alot of wood compared to my other smokers but they were cheap thin smokers, chargrillers from home depot. i used about 4 or 5 pieces split wood 18 inches long maybe a little shorter they fit in my firebox good, also kept the damper all the way open temp spiked a couple times closed the damper and it immediately went down heck it could be that its a whole new game with a reverse flow as my other one was conventional. Anyway maybe the pics will help, Thanks again.
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bluegrassmichael
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Re: Newb pit build question

Postby bluegrassmichael » Sun Jun 14, 2020 8:28 pm

More pics.
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hogaboomer
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Re: Newb pit build question

Postby hogaboomer » Mon Jun 15, 2020 12:46 am

I've found those type of thermometers less than accurate. Like 50 degrees lower than what a digital probe laying on the grill reads.
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k.a.m.
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Re: Newb pit build question

Postby k.a.m. » Mon Jun 15, 2020 2:55 pm

The numbers do not add up for me but you are done and painted so learning what you have is the best approach. 25° left to right is nothing to be concerned about in my opinion how big of a coal base are you running?
There are several contributing factors I believe that are keeping you from consistent temps.
Firebox is undersized and the exhaust is too tall for that chamber set up.
Always remember slow and steady wins the race.



My Hybrid cooker.
Competition trailer #2.
bluegrassmichael
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Re: Newb pit build question

Postby bluegrassmichael » Mon Jun 15, 2020 5:11 pm

I was concerned about the smokestack ,how long do you think it should be? I fill a whole chimney up with coal and throw a couple sticks of wood on top of that. The Firebox well it's already done now but it sure looks big setting up on the side of that tank if you was up looking at it up on it but like I said it is what it is I guess thanks again for your help
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hogaboomer
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Re: Newb pit build question

Postby hogaboomer » Mon Jun 15, 2020 5:30 pm

According to the pit calculator site that shall remain nameless - your firebox is at 84% and your stack should be 20.5 inches tall. Your firebox intake is good.

It also says this about chimneys:

• A chimney that is too short may produce insufficient draft (drawing of air). A chimney that is too long may cause the air to cool before it exits, reducing effective draft and worse, dripping of exhaust materials onto food!
• Many horizontal smokers have an exhaust between 30-40 inches in length, but there is no hard and fast formula.



Your fire will burn hotter if you leave the firebox door open a bit. More air, more heat.
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k.a.m.
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Re: Newb pit build question

Postby k.a.m. » Tue Jun 16, 2020 4:01 pm

bluegrassmichael wrote:I was concerned about the smokestack ,how long do you think it should be? I fill a whole chimney up with coal and throw a couple sticks of wood on top of that. The Firebox well it's already done now but it sure looks big setting up on the side of that tank if you was up looking at it up on it but like I said it is what it is I guess thanks again for your help

24" tall would work nicely.
Your fire starting sounds like a good start.
Always remember slow and steady wins the race.



My Hybrid cooker.
Competition trailer #2.

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