Author Topic: Want to build a gas fired deck oven. Any plans available and suggestions?  (Read 31340 times)

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Offline Sqid

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Bob - I absolutely agree it's time to make some decisions.  I shall be in Thailand tomorrow and want to get this project underway.

So far I've decided to go for a 4'x 2.5' oven with probably an 8" or 9" head height (I sometimes make bread for my family and evn eith the 12" clearence I have at the moment it can be difficult getting the pies at the back).

Burners I want will be 2'x3.75'.  Looking for even heat distribution.  Total of 120,000 Btus.  Haven't located a sure source yet but maybe tomorrow!  Depending on price and availability I may buy more than one unit or more than 120,000 Btus so I have the option of a top burner.  Looked at the forum link you posted and I'm pretty sure that they could help me make what I need but I'm not too good at typing and don't fancy joining just yet.

Regulator is not needed at least on the bottom.  If I need for the top I don't know if I can find iot here or maybe in Thailand.

PDI or thermostat.  I would love to know more.  It seems that a thick stone will do a fairly good job of evening out the hearth temperature but PDI sounds great.  Why doesn't every oven use one?  Again could do with deciding on this whilst in Thailand.

Ignition systems - They are going to crucify me (on price) if I go to one of the 2 oven suppliers in this country.

Digital readouts - Maybe in Thailand

Steel, shelves.  Here in Burma :D


Offline shuboyje

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I just wanted to make sure you didn't miss it :).  It's a good resource

You are in uncharted territories, in my opinion you should take as much time as you can to work out a design.  I can't even tell you how many hours I spent on the design of my last oven.
-Jeff

Offline Sqid

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I was going to add that although steel is available, I'm not sure abou aluminized however I know I can get aluminium sheets.

I would love to design this to perfection but it's really a means to an end.  Frankly I think I/we'd be hard pushed to come up with a worse design than what I'm using atm!

scott123

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Just to be clear, I don't think there is any issue with a bottom heat only oven, I just think it would lead to a lingers more complicated design phase and then a good deal of trial and error to get enough heat up top.  We've probably all seen the work that has gone into getting top heat on a lbe with its MASSIVLY over sized burner and it still ends up a losing battle most of the time. I still really think the extra cost and complexity of the top burner would end up being more economical in time and money at the end of this project.

As I mentioned before, an LBE and a bottom heat gas deck are apples and oranges.  Here's a video of what the Marsal MB gas oven can do:

http://www.history.com/shows/food-tech/videos/playlists/full-episodes#food-tech-pizza

The Marsal component is at the 36:45 point.  If anyone has trouble playing it, PM me, I have a small clip of that segment.  I'd upload it to google but I'm not sure how small the clip has to be for fair use.

Anyway, if you look at the pizzas he's producing, there are no top heat issues whatsoever.  There's also very little turning involved, and, because of the thermal mass and btus involved, these ovens recover very quickly.

The secret to the MB thermodynamics is the side vents (see below).  This would be difficult to incorporate into an LBE and is why some LBE owners have a hard time, although the greatest headaches are the owners attempting Neapolitan.  NY in an LBE isn't all that complicated.

Richard, take a long look at this video, not just for the quality of pizza a bottom heat oven can consistently produce, but because they give you glimpses of the manufacturing process as well as the burner.

They also use metal heat deflectors under the burners, found here:

http://www.marsalsons.com/default.aspx?pageId=2

scott123

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Here's some more shots of other gas oven burner configurations:

http://www.ebay.com/itm/BLODGETT-1048-1060-BURNER-SET-BURNERS-PIZZA-OVEN-/280739190641

and below:

scott123

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Beyond the forum links for burners, here are a few videos.







You've got your Drago type burner as well as pipe burners. I'm including these links with the usual caveat- if you don't have access to someone who's made a burner before, I wouldn't make a burner yourself.

If you've got a local guy with galvanized pipe burner making experience, then I might give him a ring.

Offline shuboyje

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Where is the flue located in the MB ovens Scott?

Watching that video I'm shocked by the simplicity, I don't see anything that couldn't be built into a LBE easily, I wonder why there is such a vast difference in this ovens ability to get heat to the top without deflectors, with a much higher ceiling, and without a front vent that causes the hot air all to cross over the pie.

If it really is as simple as it looks, building a bottom burner only oven should be easy.  That oven doesn't even look to be insulated.  With my skills as a sheet metal worker, access to a shop(which I have), and a pile of stainless I could build that in a day.
« Last Edit: July 15, 2012, 02:49:01 PM by shuboyje »
-Jeff

scott123

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Jeff, when I started researching gas deck ovens, I, too, was surprised by the simplicity of the heat deflection.

The flue is in the center back.  I can't seem to find any parts list, but I'm guessing there's most likely a vent over the center ceiling bricks. I kind of doubt that this has Neapolitan oven style exhaust heat recycling.

While it is simple, I'm not so sure it would be that easy to incorporate in the LBE.  I've been recommending thermal mass for the ceiling of the LBE for quite some time, and, so far, no one's really warmed up to the idea.  Firebricks and 2" Fibrament are naturally diffusive, but Fibrament isn't sturdy enough in a high pressure burner setting and firebricks take a long time to pre-heat and are a hassle to cut. Chau went the firebrick route on one of his builds and I believe had fantastic results without any deflector in place.  Still, it's a lot to expect for people to work with 1.25" - 2" hearths- and the hearth thickness/conductivity plays a big part in the mb.  An mb wouldn't work with cordierite. As far as channeling the heat up the sides, into the oven chamber and then out the top of an LBE... I don't see how you could do it without some welding. A deflector under the stone with tall lips on two sides might work, but you'd still have to exhaust everything through the middle of ceiling.

Hmmm... if there was a 19" steel cake pan that you could put an 18" stone on (propped up a fraction of an inch for deflection). Then you could hang a 21" stone about 1" up from the cake pan, with a hole in the stone to vent gas.

Anyway, you get the point, translating the mb setup to an LBE- not as easy as you might think.

Offline shuboyje

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Scott,

As for the LBE I think a lot of it may be the definition of easy.  I sometimes I forget that everybody doesn't work with metal for a living, let alone even work with their hands for a living.

Back to the issue at hand.  I did a bit of reading on the MB website and found their brick lined ovens have a 6" vent.  I matched the bypass sizing to that flue size to come up with some numbers.  I also found the deflectors are 10 cause metal.  I've taken the dimensions Sqid has already posted into consideration and made a simple sketch just to see if we are on the same page.  I took the liberty in adding 2" of insulation all around, I can't see how the oven wouldn't benefit from it.

-Jeff


scott123

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Jeff, don't forget the inner steel sheet that creates a channel up the side (see below)  Btw, are you sure about the 5/8" gap?  I thought I recalled seeing something about a 1 3/4" channel. If you look at the screenshot below, you'll see that the gap looks like it's wider than an inch.

Also, speaking of channels, I noticed that they were using solid steel on the inner wall, but now they've added holes. I guess the holes might help.  On some ovens, such as Baker's Pride, the side wall goes all the way to the top and it's just holes.
« Last Edit: July 15, 2012, 06:51:04 PM by scott123 »

scott123

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Re; insulation; like all modern decks, this will be cool to the touch on all non door areas, so it's insulated. It's probably a thin, quality insulation.

Doh! you can see the yellow insulation in the photo I posted.
« Last Edit: July 15, 2012, 07:18:47 PM by scott123 »

Offline shuboyje

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I was about to say the same thing, you can see the mineral wool in that picture, lol. 

I left the walls out for simplicity since it was just a rough sketch.  The 5/8" was based off of my experience with airflow.  Two 24" x 5/8" channels would match the flue.  You would have the same amount of air moving through the channels at the same velocity as you would have moving through the flue.
-Jeff

Offline Sqid

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Great info.   The internet can run very slow here at times (12Kb/s) so I haven't had time to look at utube and the food spec is denied for some reason.  I found a torrent but that is also not doing it.  However I will be in Thailand in a couple of hours and will look then.

I forget what you guys take for granted.  Picking up the phone to phone to call the "galvanized pipe burner maker" is not an option here.  Difficult to find out who does it and phone lines still cost $230, better than the $2000 you had to pay 2 years ago, but still out of reach for most of the population.  I cannot buy an 8mm star screw - 7 or 9 yes but the 8 can be worked around so no body stocks them and I mean no body!!!

The 5/8ths and 1"3/4.  Is it possible that you don't want all the heat rushing out through the flue?

Still can't help thinking that a top heater may come in useful when the oven is being opened a lot.  I know it's not the same but if I haven't cooked anything for about an hour in my Sinmag then the bottom will char before the top is cooked.  Like the idea of top heat on demand.  But just my 2c from my fickle mind.

Any thoughts on relative advantages of PID vs thermostats?

Thanks for getting into it.

Offline Sqid

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Well, today wasn't so productive.  One of the hot leads I had wanted to charge me 20000 Baht for double line  120kBtu stainless burner.  Tomorrow I shall ask around Yaewat (where they sell the catering equipment) and in China town where they also make equipment.

Btw I didn't mention but the cad drawings are very impressive.

Offline Jet_deck

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Nothing inside the oven should be galvanised steel, including the burner.
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Online Chicago Bob

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Nothing inside the oven should be galvanised steel, including the burner.
Not trying to start an arguement.....but on a couple of those diy pipe burner sites they say galvanized is ok but why bother with additional expense when it's just going to get burned off by the high heat. Also, a lot of them prefer what they call "untested" pipe rather than plain 'ol black pipe because (they say) it is thicker...
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Offline Sqid

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Nothing inside the oven should be galvanised steel, including the burner.

Why's that Jet?


Offline Jet_deck

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Galvanization poisioning.  Although maybe not likely at these oven temps.  But why take an unnessary risk?  You rarely see galvanised anything in any food service item, especially around heat.

Others will say that galvanised has to reach (blank) temperature before it starts releasing its deadly fumes.  I say it is a risk that is easily avoidable. >:D
Her mind is Tiffany-twisted, she got the Mercedes bends

scott123

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Because ungalvanized steel flashing is so hard to find, I've been recommending galvanized for grill mods (with a caveat about the dangers of zinc), but, in this instance, where steel parts are just as easy to obtain, I'm with Gene.

Offline Sqid

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So more exploring today in Bangkok.

I found someone who will put an H shaped 2 line burner together for me in stainless for 4000 Baht (about $125).   Seemed like a nice fella, other things I asked about he quoted about 1/2 the price that neighboring shops were quoting.  The pipe would be about 25mm diameter and 1mm thick.


Offline Sqid

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Finally got to see the food-tech video thanks to a pm to Scott.   Very interesting to see so many stages of pizza construction, sadly when I got to the bit about the Marsal MD I had already seen it.  Its on Utube somewhere.

On the burner front am I going to be using a ton load more gas by increasing the Btus.  I presume that if I insulate the box well that the increase wont be that dramatic.  I presently go through about 5 Kg of natural gas a day.

Offline Jet_deck

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What safety features do you plan to employ?
Her mind is Tiffany-twisted, she got the Mercedes bends

Offline Sqid

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Hi Jet

At this stage I just plan to see that he uses good quality steel and that the joins are well welded.  Do you have any suggestions?

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 Jet_deck

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Hi Jet

At this stage I just plan to see that he uses good quality steel and that the joins are well welded.  Do you have any suggestions?

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?

None of your replies are safety features.

Multiply this by 10  http://www.pizzamaking.com/forum/index.php/topic,15123.0.html

Do you have a good friend and a pair of pliers?
Her mind is Tiffany-twisted, she got the Mercedes bends

Offline Sqid

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Do you have any thing constructive to add?   I'm a long way off from lighting the finished oven.