Author Topic: Help Chau make a Poor Man's Dry Stacked WFO!  (Read 2042 times)

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Offline Jackie Tran

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Help Chau make a Poor Man's Dry Stacked WFO!
« on: June 04, 2013, 08:47:32 PM »
I'm sure many of you are thinking "But doesn't he have a WFO already?"  Well I did.  The house will be sold off next month so I'm saying bye to that oven.  Well I need something to cook pizza in the meantime.  And while I have an LBE and an electric oven at the rental, I'm really curious about one of these temporary Poor Man's WFO.   

Requirements - It needs to be relatively low cost and one that I can tear down and move, thus the dry stack wfo.

The place I am renting, there is an old non functioning bbq/grill pit in the backyward.  See picture below.  It is made of brick and has a limestone top that measures 60" L x32" W.  The pit is 31" L x 21" W x ?  The landlord lives in another state and pays a local realty company to manage the place.  If any objections arises, I can always tear it down relatively quickly.

The bbq sits against a storage shed made of cinderblock and also has a brick backing.  I'd like to build the wfo right up against that brick backing.  It's definitely not a fire hazard BUT I'm not sure it would pass fire code.  I don't know what the fine would be and don't want to find out the hard way either.  What should I do?  Submit my plans to the fire department? to the city for approval? There is already an existing bbq pit,  I just want to extend it up about 16"-20" and cook pizza inside it.   :angel:  If I ask the realty company for permission, they can always say no.  Is it terrible that I want to build it and remove it if need be down the road?

The Plan - I'd like to put a sheet of concrete board over the top of that pit and then pour about an inch and half of perlcrete over it so that it is flush with the table top.  Then I'd like to build as big of a wfo out of clay bricks as I can over the top of that entire table (60" L x 32" W).

Ideally I'd like to be able to build the fire towards the left side and have it rolling right towards the pit side.  That's where the pizza will be cooking and that's why I want to insulate that spot.  Below that layer of insulation will be the old grill pit so it will just be air down there.  Also that pit has a brick bottom.  I just haven't measure out how deep it is yet.

Questions
clay vs firebrick hearth? - What would you build the hearth out of?  Which would you think is better and why for this type of oven?  I can always try both and see what works better as well.

I'm thinking of building this stacked wfo 12" high from floor too ceiling.  Will this be high enough to build a fire inside or should I go higher?  I realize NP ovens are 10-12 inches high but this isn't a NP oven.

Can I lay clay bricks or firebricks directly over the limestone table top and build a fire over that?  Will the limestone crack from the high heat of the bricks (800F + on the side that is touching the limestone table top).  Or should I place a sheet of concrete board between the limestone and the hearth?

Chimney
I'd like to have the chimney over on the far right side of the oven so that heat will hopefully travel from left to right and up.  I'm also thinking of routing the chimney from the right side back towards the left side like a NP oven, thus creating a false ceiling or 2nd ceiling?   Good idea or not?  Waste of time and brick or not?

Poor Man's insulation - maybe cover the oven with a layer of foil then some insulating blankets during the bake.  I can always remove the blankets after the bake and fold them up and put them away.  I don't want to insulate and stucco this thing in case I have to take it apart or want to modify it later.

Anyways, all suggestions and comments welcomed.  Thank you as always. 

Chau
« Last Edit: June 04, 2013, 09:07:56 PM by Jackie Tran »


Offline Woodfiredovenpizzero

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #1 on: June 04, 2013, 09:16:35 PM »
Quote: If I ask the realty company for permission, they can always say no.

Chau:

A lawyer once told me: It is better to say sorry than ask for permission  >:D. Well, it wasn't my lawyer... :-D.Well anyway,I wish you luck in your new endeavor. I'm not the expert on bricks, but, are those refractory bricks?

Edgar

Offline Tscarborough

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #2 on: June 04, 2013, 09:22:46 PM »
Is there a door on the side not shown?

Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #3 on: June 04, 2013, 09:24:35 PM »
I agree with you Edgar.  Easier to ask for forgiveness than ask for permission.  But I would really hate to get slapped with a fine by the fire department!  :o  I'll have to contact the guys who put my wfo together at the house and see what hoops they had to jump through to get clearance for that WFO?  Last I remember, they said something along the lines of it had to be so many feet from the house and not back up to another house.  But again, there is already an existing bbq pit, plus this house was built in 1902?  so it's in a neighborhood that is considered a historic landmark.  Anyways, I am not altering the house in anyway.  I just want to extend the existing bbq pit...or transform it into a pizza oven.

Yes those are a few firebricks I have laying around.  I would have to source more firebricks for the project or clay bricks.  I'm thinking clay bricks would be lighter and cheaper.   But I also want to be able to reach NP temps 800-900F in this thing.  Anyone think it is possible?

Chau

Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #4 on: June 04, 2013, 09:27:18 PM »
Is there a door on the side not shown?

Tom, Just the man I need to talk to.  No door on the side of the table.  Just brick on both sides.  The oven would go on top of the table.  That shelf you see is about 14" above the table, so that entire brick backing is about 30" or so.  If need be, I would remove that shelf!  >:D  I'm sure no one has used it in years and would not miss it at all.  8)

Tom, I was also thinking about leaving the left side of the oven open to load wood into and after the fire starts, I can cover up that side with a piece of concrete board and then bricks.  Would the concrete board hold up to the heat and is there any harm in burning concrete board?  Will it release harmful chemicals?

Chau
« Last Edit: June 04, 2013, 09:33:54 PM by Jackie Tran »

scott123

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #5 on: June 04, 2013, 09:42:49 PM »
Hmmmm... this is a complex project here.

First off, for reference, here is the, imo, reigning mortarless oven build:

http://www.pizzamaking.com/forum/index.php/topic,18944.0.html

This is one of the few (only?) builds to build more than just a box out of bricks. You don't have to mimic him, but I would read through the thread for inspiration.

You really want to stick to the 60% door rule. 12" on an oven this size, translate to 8" on the door, which might not give you good access to the whole oven.  I might go 13, maybe even 14, but no higher than 14.

The name escapes me, but you want the special low conductivity firebricks that Jeff introduced to the forum for the hearth, if you can get them.  Domestically, I don't think anything can beat those.

Can you find out what existing permits there are for the pit? That might help you understand what can exist there and if you can squeeze into that.  The thought of paying inspectors to build a temporary oven causes me great angst, but, the thought of telling no one bothers me more.  There's also a really good chance they might force you to extend the chimney above the structure- and attach it. Still, I think you have to talk to the authorities.

A Neapolitan vent is questionable for a mortared oven, but, for a mortarless oven, the logistics make it even less desirable. 

I kind of like having the chimney a level below the main oven ceiling and the door a level below that, but, that was while I was still using the theories for the FGM throat reducer.  Since the throat reducer is in flux, the theories are in flux as well.

Is the center of the limestone table supported? 

Perhaps I'm not hearing you correctly, but I wouldn't put bricks straight on limestone- not that they'll crack- the bricks should ensure very even heating, but because you want a layer of perlcrete.

The oven has to be weatherproofed.  The bricks cannot get wet, either during the cooldown or between bakes. If you're only going to bake when you're sure you're going to get two days of good weather, then you could bake, let the oven cool, then cover it with a tarp, but that sounds like a hassle.
« Last Edit: June 04, 2013, 09:47:41 PM by scott123 »

scott123

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #6 on: June 04, 2013, 09:45:49 PM »
Oh, and I really like the lateral oven idea, but I think 60" is overkill- unless you plan on doing some serious entertaining.

32 x 45 feels better.  Maybe 32 x 50.  But no larger than that.

Online JD

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #7 on: June 04, 2013, 09:54:29 PM »
I would be very surprised if a mortarless oven was considered fire safe. But you know what they say about assumptions...

Looking forward to seeing your results!

Josh

Offline Tscarborough

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #8 on: June 04, 2013, 09:57:11 PM »
I would bone up on your kitchen oven skills (not that you need to) and cook fajitas on that grill.

Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #9 on: June 04, 2013, 11:39:32 PM »
I will call up the guys who put together my wfo at the house and see what they had to go through to pass fire code here in Albuquerque. 

Scott, yes I would like to build it just big enough for a decent fire and enough room to cook one pie at a time, so I may not need all that space. 

The bricks you are thinking of that Jeff uses are Whitacre Greer I think.  I will have to PM Jeff again if I move forward with this project. 

The center of the limestone table as a whole is supported by brick.  The left of the table is just a limestone slab and doesn't have support directly under it.  The lime stone slab is about 2" thick.

Thanks for the tips and suggestions!

I would be very surprised if a mortarless oven was considered fire safe.

JD, what do you think could happen?  Do you think this thing could blow up? The fire will be contained inside the oven.  The bricks will be stacked tight as I can get them.  There won't be any kids running around and I will make sure everyone knows that it is HOT and not to touch it.

I would bone up on your kitchen oven skills (not that you need to) and cook fajitas on that grill.

The grill itself is no longer functioning.  Yes I could fix it and use it as a grill but I already have a grill.  What I don't have is a WFO at the moment.  The kitchen oven is an electric oven, ie broilerless.  What concerns do you have with this project?  Please indulge me.

Chau


Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #10 on: June 04, 2013, 11:48:03 PM »
From Michael's thread.
http://www.pizzamaking.com/forum/index.php/topic,18944.msg203979.html#msg203979

"Deck temp was about 800F and so were the walls. Fired the oven for about 7 hours prior to bake. I think with the limited insulation I currently have those are the highest temps I will see."

DAMN!!  :-\

scott123

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #11 on: June 05, 2013, 12:18:41 AM »
Jackie, with insulating blankets, rather than perlcrete, I think you'll hit higher temps. It's also possible that, with my (then) drive for the lowest dome possible, I might have pushed him towards something too low and impacted combustion and/or fire size.

As long as your bricks and wood are dry and you've got a good layer of blanket insulation, I think you'll drive the temp up as far as you want.

I've never worked with limestone, so I'm not sure of it's flexural strength (or how much flexural strength is required in this kind of scenario). If the middle area wasn't fully supported, I probably would have said no, but, now that it is supported... I'm going to have to defer to someone else.  Tom?

Do you have any access to freeweights? You could take a couple hundred pounds of barbells and place them on the limestone and see how it fares.  I don't know, just spitballing :)

Whitacre Greer.  Yup, those are them.  Accept no substitutes  ;D

I think JD's comment about fire safety related more to a possible inspection than to the actual  safety of the device.  As long as the bricks are dry, this is safe. I feel pretty strongly that you should stick to firebrick, but you'll find different opinions on that.

The one piece of advice that I would give to you that I didn't give to Michael is refractory thickness.  I would go as thin as you can on every dimension.  You can't go 1 1/4" on the walls, due to stability, but you can on the ceiling- and don't double up anywhere, if possible.  It's going to limit any potential for retained heat cooking, but the lower thermal mass will shorten your pre-heat times considerably.

In fact, if you have the money to spend, I might take it a step further and purchase smaller cordierite kiln shelves (1/2" thick) and use those as tiles for the dome. As long as the tiles are insulated, they'll get way hot, stay way hot, and toss off just as much IR as brick- as long as you've got a fire lit.

Offline flyboy4ual

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #12 on: June 05, 2013, 04:10:18 AM »
Put it on wheels, then nobody could say anything about it!  Good luck.

Scott D.

Online JD

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #13 on: June 05, 2013, 07:49:25 AM »

JD, what do you think could happen?  Do you think this thing could blow up? The fire will be contained inside the oven.  The bricks will be stacked tight as I can get them.  There won't be any kids running around and I will make sure everyone knows that it is HOT and not to touch it.

Scott was correct, I was thinking along the lines of inviting an inspector to your home and (in my opinion) most certainly being shot down... and then subsequently being watched closely. My rationale is that no mortar = no strength, and if something were to fall on it while under fire (say a tree limb), it would pose a serious risk to adjacent property.

I'm in the same situation as you, moving in 2 years or so but itching to make a WFO. I'm most likely going to build a mortarless WFO as well, but maybe i'll wait for you to do the hard work and I'll just copy you later :)
Josh

Offline wheelman

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #14 on: June 05, 2013, 09:05:33 AM »
Chau,
will you need front and back walls?  if so, the 32" depth is going to be down to super tight.  can you cantilever a landing and the chimney to buy some more room?
does the new dig have a garage? 
bill

Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #15 on: June 05, 2013, 10:47:43 AM »
Scott, glad you think I can get the temps higher than 800F with insulating blankets.  I just don't know how fireproof they are.  I'll have to do a little research if this project goes forward.  I'm thinking something like Craig used for his BBQ.
http://www.pizzamaking.com/forum/index.php/topic,9614.msg83372.html#msg83372

12" may be too low for this type of oven.  14-16" might be more appropriate.  Low ceilings work well in NP ovens b/c you can spread the coals around and place more wood on top to burn down.  A BIG limitation to this type of oven is limited access to add wood or move the coals around.  If the mouth of the oven is too big then you lose a lot of heat.  If it is small enough to retain heat, then you lose access to the coal pile.

Good idea on the weights.  I'll give it a try.  100 lbs. should be more than enough I think.

I agree on the inspection by the Realty company.  There's always a chance the FD will come around if the neighbors complain of excess smoke. 

I like you idea on refractory thickness.  Yes these types of ovens are ideally quick heat ups, with an active fire, bake a few pies and then shut it down.  I don't see the sense in a 7 hour heat up time unless you have an endless supply of free wood, which I don't. 

I may have to do clay bricks for the oven and firebrick for the hearth and ceiling.  Do you know the conductivity difference between clay bricks and Firebrick by any chance?  Is one lower or higher?

JD - I agree about the stability issues.  There are no trees or dead trees nearby to fall on the oven.  I guess a drunk person could fall on it as well, but none of my guests get that toasted.  If they do I will keep them inside.  But I hear ya.  That is the big dilemna at the moment.  Ask and have someone say no or apologize for it later and face possible fines.  Dangerous? I am not seeing it.  But I will ask around and try to find out more info first. 

Bill - I was going to do back and front as well.  I could just do the front and either do sheet metal or concrete board for the back right up against the existing bricks.  Thoughts on that ?

No garage in this one.   

One other option I haven't explored that I have wanted to in the past, is to just do what Craig did with his grill with rotisserie.   That would solve a lot of my issues here.  If I could get 850F in a gas grill with rotisserie and insulation blankets, that would save a lot time and headache.   ::)
« Last Edit: June 05, 2013, 10:57:55 AM by Jackie Tran »

scott123

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #16 on: June 06, 2013, 02:17:02 AM »
I think clay is less dense, and thus less conductive than fireclay, but Tom's the guy that knows bricks.

When I mentioned insulating blanket, I was referring to this:

http://www.fornobravo.com/store/FB-Blanket-50.html

I'm curious, are you considering this oven as a one off until you find a permanent place where you'll most likely get something modular like you had last time, or do you think you might incorporate the materials from the mortarless oven into something that you end up building permanently?

Before I started micro-engineering Michael's oven with him, he was doing some amazing pies.  If this is going to be a build it and, eventually toss it, kind of oven, I say get some firebricks and some angle iron, cover the hole with plywood and then cover the table with 2" of leveled perlcrete, and build the chimneyless box you see on most mortarless builds, except, combine the box with an insulating blanket.

If worse comes to worse, if you can't quite hit the temps you want, you can always get there with malted flour (kaap). It'll be mortarless, so if you want to change the configuration and add a chimney, you can.

Could you lease a mobile oven for a few months from Antoine?   :-D

Offline Jackie Tran

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Re: Help Chau make a Poor Man's Dry Stacked WFO!
« Reply #17 on: June 06, 2013, 11:09:07 AM »
Scott, I'm not sure that insulating blanket would be the best choice.  I think it may have fiber glass in it or something like that.  From what I can remember, it's not a material that you want to handle without gloves on.  So it might not be a good material to be putting on the oven and taking it off.  I think it's meant as a one time application.  Put it on and leave it on.  I could be wrong though. 

 
I'm curious, are you considering this oven as a one off until you find a permanent place where you'll most likely get something modular like you had last time, or do you think you might incorporate the materials from the mortarless oven into something that you end up building permanently?

Yes, I'm not sure how long I will be in this rental but it will be short term.  I guess it may be better to just invest in a real mobile oven if I really need to have one.  I like your idea of renting one for occasional use.  I just eyed a pizzeria a few streets over from where I am staying and they have a mobile wfo.  I will talk to them about renting their mobile wfo.  I don't know what brand or model it is but I am sure I can get it to work.

I really just saw this old non funcitoning bbq grill in the backyard and thought that space would be great for a makeshift wfo.   I was hoping for an inexpensive quick build that would get me through this temporary period.  But yes a build it and eventually toss it kinda deal. 

Thanks for your ideas Scott.   I'll put this project on hold for now until I can inquire about permits and code.  I may also price out a mobile unit with Antoine. 

Thanks again,
Chau