Author Topic: Want to build a gas fired deck oven. Any plans available and suggestions?  (Read 20050 times)

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buceriasdon

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Richard, Ignition can take place anywhere there is a flame hole, the flame starts at one end and moves to the other, hence the holes in the cross tube of the H to enable this to occur, if using a single venturi. Some H burners have two venturi tubes and control valves so they are lite separately, not required for this application. The most critical part of the construction is the venturi port, the place where gas and oxygen mix.
Don



I presume the cross pipe of the H is also perforated and that is where the ignition starts from.  Is that correct as far as you know?


Offline Sqid

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What I would like Gene is any suggestions about how it should be made.  I intend for it to be safe and will cross those bridges when I come to them.  

I would like any suggestions on how to make this 1st part safely and on the dimensions suitable for a 2'6" x 4' interior.  Should the uprights of the H be 3'6" long and how long should the cross be (18"?).   Any suggestions for the gap between the holes.

Also the main lead in gas pipe.  How long should I leave it protruding the H in order to fit all the gubbins on later?

Offline Sqid

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Yes Don

I noticed that.  I did see some weber burners and some Chinese stainless burners.  They both had a wire mesh near the entrance which I presumed was to let air in.

However the Thai made black pipe burners didn't have any thing at the front end, only a straight tube with holes in it.

I wonder if they mix the air before it gets to that point.

Offline scott123

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Your burner guy should know where to put the holes for the burner.  He understands BTUs, correct? If your burner guy is depending on you to choose where to put the holes, then I think you need to put in at least a couple days reading through the burner forum that Jeff posted a link to. Even if he knows what he's doing and is building you something very close to 120K Btus, I'd still spend some time reading through that forum. You cannot learn too much about inspirators, venturis, and stoichiometry. Instead of asking us questions on building burners, you should be research the living crap out of this and telling us how to build burners. As far as I can see, that's the only way you're going to know that the setup is safe and to be able to sleep well at night.

Or you can save yourself some of that research time and buy a commercial burner. How much were the Weber and Chinese stainless burners you saw?

Marsal does an H-ish shaped burner, but they also incorporate deflection- deflection that isn't shown in the video.  If I were building this, I'd probably go with four 12" x 28" stones, with a 24" pipe burner centered under each. You could probably go with an H burner and simplify the deflection with one solid plate of steel, but an array of 4 pipe burners would spread the heat a bit more reliably.

When it comes to safety, I think the most important aspect is making absolutely certain that the burner always stays lit with an incredibly reliable pilot light.  These kinds of homemade burners can easily go out, and, if they do, and the gas keeps flowing without re-ignition, you have a gargantuan problem.

Offline Chicago Bob

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What I would like Gene is any suggestions about how it should be made.  I intend for it to be safe and will cross those bridges when I come to them.  

I would like any suggestions on how to make this 1st part safely and on the dimensions suitable for a 2'6" x 4' interior.  Should the uprights of the H be 3'6" long and how long should the cross be (18"?).   Any suggestions for the gap between the holes.

Also the main lead in gas pipe.  How long should I leave it protruding the H in order to fit all the gubbins on later?
What happened to the 4,000 Baht guy?
"Care Free Highway...let me slip away on you"

Offline Sqid

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Thanks for the replies.

I'm doing my best to research this, unfortunately I'm on a bit of a short leash as far as time is concerned.

I'm figuring that I get the burner made here in case they can't do it in Burma.  When I get back I can find out but if they can't then I would have to make a special trip just for it. 

Bob - It is the 4000Baht guy and he knows what he makes which is a cast iron 15" H burner and 2'6" black pipe burners.   That's it.

Offline Chicago Bob

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"Care Free Highway...let me slip away on you"

Offline Jet_deck

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There has got to be a wok burner overthere somewhere.
Her mind is Tiffany-twisted, she got the Mercedes bends

Offline scott123

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Not a bad idea, Gene.  A wok burner wouldn't spread the heat like a pipe burner would, but, with extra deflection (thick steel?) a series of wok burners might work.

buceriasdon

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N.G.wok burners are very specialized because natural gas is low pressure hence more expensive. Plus the added complexity of multiple piezo igniters makes wok burners not the best choice, IMO in this configuration.
Don


Offline Jet_deck

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Don is correct.
Her mind is Tiffany-twisted, she got the Mercedes bends

Offline Sqid

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Bob, the link you posted is very similar to the 15" cast iron burner that is available here for about $80 but I rejected it and wok burners for precisely the reason Don gave.   Here they use multiple burners on their home grown systems but they light each one separately.

I've ordered a burner this morning - no idea if it will work - guess we will see!  Should be ready in a couple of days.

Offline Sqid

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Looking again at your link Bob.

How do you know what Btu its rated for.   Same thing here.  No one really knows.  Does it just depend on the amount of gas you push through it?

Offline Chicago Bob

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Looking again at your link Bob.

 Does it just depend on the amount of gas you push through it?
Amount of gas(orifice size) AND air shutter/flow venturi...I really think you need to take Scott'S recommendation and have a 'lil time out here to do some (at minimum)basic reading. Before you blow something/somebody up.... ;)
« Last Edit: July 18, 2012, 10:55:17 AM by Chicago Bob »
"Care Free Highway...let me slip away on you"

Offline MightyPizzaOven

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Checkout this link, http://www.tejassmokers.com/castironburners.htm they make custom burners, it might be worth talking to them for your application.
Bert,

Offline Sqid

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Been doing lots of reading Bob and Scott :-D.  It seems to me that you can determine Btus by knowing how much gas is being consumed efficiently.  Maybe I will do that when I get home.

Picked up the burner today and for sure it is not putting out 120 Btu.  Try and post some pics when I get home.

Offline Sqid

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Re: Want to build a gas fired deck oven. Any plans available and suggestions?
« Reply #116 on: August 25, 2012, 10:38:48 PM »
Hello all.
Haven't done alot with the burner since I've been back.  I estimate that it's putting out about 50000 btu.  It generally lights very well but sometimes needs a little puff of air to get the flame to move along to the next port.

For these reasons I don't think it will be suitable for the bottom burner.

I've also taken a closer look at the gas control system on my present oven.  It has a blower to mix air with the gas before it ignites.  I expect that will change the btus on any burner I end up using.

Been looking at stones for the hearth.  Kiln shelves here are either natural stone or metal as far as I can tell.  The local made refractory bricks are very brittle and uneven sizes.  What I can get; are some old imported refractory bricks that are 2"x9"x9".  This is less than ideal because the heat will not disperse as evenly as across a single slab.  I was thinking I could counteract that by adding a 1/4 or 1/2" slab of alluminium under the bricks.  Any reasons why this might not work?

buceriasdon

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Re: Want to build a gas fired deck oven. Any plans available and suggestions?
« Reply #117 on: August 26, 2012, 07:42:07 AM »
Hello Richard, Even though aluminum is many times more thermally conductive than steel I'm sure the sticker shock at it's price will have you thinking about steel plate.
Don

Offline scott123

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Re: Want to build a gas fired deck oven. Any plans available and suggestions?
« Reply #118 on: August 26, 2012, 07:56:55 AM »
Don's right, aluminum is not going to be cheap.

You want a steel plate that's just thick enough so that it doesn't warp. I'm thinking 1/8."  If it warps and the bricks don't contact it evenly, you'll have uneven heating. Also, try not to go too wide and long with the plate, as the larger you go, the more propensity there will be for warping.  Cut and arrange the plates so that each plate gets an equal amount of the flame.

2" refractory bricks might work nicely.  They'll most likely be a little less conductive than what you're working with now.  Is the thermostat maxed out or can you go a little higher?

Offline Sqid

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Re: Want to build a gas fired deck oven. Any plans available and suggestions?
« Reply #119 on: August 26, 2012, 11:09:20 AM »
Hi Don, Scott.

I was thinking of an aluminium plate about 6mm thick, which I've heard I can buy at about $10 sq ft.  So for a 2'6" x 4' deck, I would be looking at about $100.  Not so bad if it heats up about 20 refractory bricks evenly.   Maybe aluminium is more expensive in the States?

Scott, I'm thinking this through for the new oven.  On the present one we've shimmed out one side of the door frame which now makes a better fit for the seals.  We don't seem to be loosing so much heat but only time will tell how long the new seals will last.

On another point.  I haven't been able to get a close up look at a typical pizza deck oven.  With only one burner how do you control the heat at the top.  Do you just open a vent when it gets over your desired temperature or is there an aperture that adjusts to only allow a certain amount of heat to move up the sides?



 

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