Can a GF be made in a RF

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sheepfarmer
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Can a GF be made in a RF

Post by sheepfarmer » August 20th, 2019, 1:07 pm

I am looking to build a GF and was wondering if I could put the outlet ports at the bottom and outlet up to the top. I love my RF and wanted to know if any one had thought of it or tried it.



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Re: Can a GF be made in a RF

Post by McBroom » August 20th, 2019, 1:52 pm

Awesome idea. I’m interested in this thought too


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Re: Can a GF be made in a RF

Post by JKalchik » August 20th, 2019, 6:24 pm

I must be completely confused. Are you talking about ducting the firebox outlet up to the top of the cook chamber, and venting the cook chamber outlet out the bottom? This would be so the smoke flows down from the top of the chamber to the bottom? I'd be willing to bet that you'd need a fully forced draft fan system for it, as the smoke would be moving against thermodynamics in the cook chamber. If you vent the cook chamber out the bottom, you're going to want to be very careful about where you site this thing, as you're going to have a warm draft out the bottom at all times, and have some fun with bottom acting as a grease pan.

I have to be completely wrong on this. Where do you want the inlet in the cook chamber, and the outlet? I'm just not gettin' it.


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Re: Can a GF be made in a RF

Post by McBroom » August 20th, 2019, 6:45 pm

^^^this^^^
I think I need to see a rough drafted picture of what’s happening.


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Re: Can a GF be made in a RF

Post by bvbull200 » August 20th, 2019, 7:53 pm

Broadly speaking, it would be the same design as a reverse flow vertical cabinet smoker. The tricky part would be getting the heat evenly across the cook chamber. With a vertical cabinet, the fire is below the cook chamber, so it naturally goes up and towards both walls relatively evenly. With a GF, the fire is to the side and then you need to get some of it up the shared wall, but not too much, then the rest across the entire cook chamber and up the other wall.

This a a VERY rough drafted picture of what it would look like. Firebox on the right, heat moves left, then up the right wall and across and up the left wall. Heat moves towards the middle section, which is the cooking chamber. Heat exits the cook chamber via an exhaust opening that sits low in the cook chamber.
GFRF.png
You could maybe get away with putting the firebox on the back wall, then making some sort of diverter that, more or less, splits the heat evenly among the right and left walls. Not impossible, but a lot of work and probably some uncharted territory.

I'd love for you to be the guinea pig, though ;).
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Re: Can a GF be made in a RF

Post by sheepfarmer » August 20th, 2019, 9:05 pm

I have a rough diagram drawn up, but don't know how to load it in the comments. Do any of you know how to load an image in the message?



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Re: Can a GF be made in a RF

Post by towtruck » August 20th, 2019, 10:50 pm

bvbull200 wrote:
August 20th, 2019, 7:53 pm
Broadly speaking, it would be the same design as a reverse flow vertical cabinet smoker. The tricky part would be getting the heat evenly across the cook chamber. With a vertical cabinet, the fire is below the cook chamber, so it naturally goes up and towards both walls relatively evenly. With a GF, the fire is to the side and then you need to get some of it up the shared wall, but not too much, then the rest across the entire cook chamber and up the other wall.

This a a VERY rough drafted picture of what it would look like. Firebox on the right, heat moves left, then up the right wall and across and up the left wall. Heat moves towards the middle section, which is the cooking chamber. Heat exits the cook chamber via an exhaust opening that sits low in the cook chamber.

GFRF.png

You could maybe get away with putting the firebox on the back wall, then making some sort of diverter that, more or less, splits the heat evenly among the right and left walls. Not impossible, but a lot of work and probably some uncharted territory.

I'd love for you to be the guinea pig, though ;).
In my experience the air is going to take the path of least resistance. That resistance can be length of travel or friction with different foods on each side. A rear inlet to make each side even in length is a start but food placement will still be a factor. Getting the air to split and turn up the walls evenly will take a separator in the center. Keeping the fire burning even across it's face then becomes a concern as well. Once that fire gets hotter on one side the pressure flow to the other side will never catch up.

I ran an open split reverse flow and the slightest interference caused the fire to burn towards the path of least resistance. I ended up isolating the two halves and split it into two smokers.



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Re: Can a GF be made in a RF

Post by Big T » August 21st, 2019, 8:32 pm

sheepfarmer wrote:
August 20th, 2019, 9:05 pm
I have a rough diagram drawn up, but don't know how to load it in the comments. Do any of you know how to load an image in the message?
Maybe this will help you out https://smokerbuilder.com/forums/viewto ... =50&t=1874


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Re: Can a GF be made in a RF

Post by bvbull200 » August 21st, 2019, 8:45 pm

towtruck wrote:
August 20th, 2019, 10:50 pm
In my experience the air is going to take the path of least resistance. That resistance can be length of travel or friction with different foods on each side. A rear inlet to make each side even in length is a start but food placement will still be a factor. Getting the air to split and turn up the walls evenly will take a separator in the center. Keeping the fire burning even across it's face then becomes a concern as well. Once that fire gets hotter on one side the pressure flow to the other side will never catch up.

I ran an open split reverse flow and the slightest interference caused the fire to burn towards the path of least resistance. I ended up isolating the two halves and split it into two smokers.
I agree. I think these concerns make this a venture that *might* not be worth exploring, but conceptually, a reverse flow gravity feed is possible.

I think the insulated cabinets get away with it because the fire is directly below, so you don't really have to transfer the heat laterally.

Great points. Thanks for sharing your experience!



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Re: Can a GF be made in a RF

Post by sheepfarmer » August 21st, 2019, 11:28 pm

trying this
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Re: Can a GF be made in a RF

Post by sheepfarmer » August 21st, 2019, 11:48 pm

Thank You Big T



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Re: Can a GF be made in a RF

Post by JKalchik » August 22nd, 2019, 7:32 am

To me, that airflow diagram just looks like a mess of headaches (no, that's not a reflection on your artistic abilities, they're far better than mine.)

Hot air wants to rise, not fall. I'd bet that'd take a forced draft to get the hot aire to flow down in the cook chamber
Secondly, you've got air moving in counterflowing directions in the same chamber. How would you work that, or how would that work?

<shrug> I'm pretty happy with my double pan GF and at least 2 fewer air paths. Temperature left & right seems to have a minimal variation, bottom to top isn't bad at all.


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Re: Can a GF be made in a RF

Post by sheepfarmer » August 22nd, 2019, 8:08 am

Thank You, it sounds as if it would be more trouble than the gain. I love my 650 gal RF that I built and use for catering and comp. and I thought if it worked so well for RF maybe it would work for my backyard GF that I am now going to build out of an old military oven (SS) .



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Re: Can a GF be made in a RF

Post by JKalchik » August 22nd, 2019, 8:54 am

<chuckle> I floated the idea of a 500 gallon propane tank smoker in the backyard, and my g/f promptly vetoed it. To me, the advantage of an RF tank smoker would be the ability to make it a stick burner. My GF is purely a charcoal burner. OTOH, I can also smoke 10 full packer briskets in about 1/3 of the sq. footage, burns just a little fuel, and can run unattended (with an ATC) for quite a few hours.

It is an interesting idea, but given the difference in air flow between a gravity fed and a tank design, I don't think that the reverse flow really applies much at all. The whole idea of RF is to minimized the temp differences between the end of the cook chambers. That's a minimal problem in a GF.


"Measure with micrometer, mark with chalk, cut with fireaxe." Ted M., USCG (ret)
"Smoked pork. It belongs in me." Giles L

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Re: Can a GF be made in a RF

Post by sheepfarmer » August 22nd, 2019, 9:49 pm

Thank You, I really love all of the input from you guys. My wife complained that I spent $1,500 on building "The Beast" ,I had most everything in the scrap yard.



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