Pizza Bob's 42" Build

[fxpose]

Re: Pizza Bob's 42" Build

I used 45 degree elbows and the chimney drafts well.

[Fairview WFO]

Re: Pizza Bob's 42" Build

Bob, yes I wanted my chimney to go up in the back so it would be inline with my back corner when it gets above the roof. You don't have to go that far back though, depends on what your after. Just draw a side elevation or piece together some test sticks to determine your height. Mine started at the top of the vent and angled back at 30 degrees until about 11'. I started mine with a flat plate connector and used 3 - 3' sections and a 30 degree bend kit. You can check FornoBravo's store to price it out. They are not very heavy, maybe 5-7# per section? Dont forget 2" clearance to all combustables. Good luck!

[pizza_bob]

Re: Pizza Bob's 42" Build

Fairview,
Thanks agin for the pictures and info on the flue. I went to a local Simpson DuraVent dealer today and priced out:

8" Anchor Plate
Two 12" long by 8" diameter straight sections
One 36" long by 8" diameter straight section
30 degree elbow kit (includes two elbows and a mounting bracket)
Mounting bracket to support and anchor pipe system to my concrete layer

The price was $863...ouch! I think I'm gonna' go for it though. I really want to vent out the middle of the hipped roof as shown in the attached picture.

Did you see my PDF file attached below?

Best Regards,
Bob

[pizza_bob]

Re: Pizza Bob's 42" Build

I finally fired up the oven for the first time tonight. Just burning pizza boxes but will get to bigger fires soon!

YouTube - Wood Fired Pizza Oven - First Fire

[DaveW]

Re: Pizza Bob's 42" Build

Congrats Bob, your oven looks gorgeous!
Dave

[Lousdepot]

Re: Pizza Bob's 42" Build

incredible brick work!! congrats

[Dino_Pizza]

Re: Pizza Bob's 42" Build

Nice video Bob, congratulations on your 1st fire. How many have you had now? Are pizza temps coming this week?
Cheers, Dino

[pizza_bob]

Re: Pizza Bob's 42" Build

Thanks Dino! The pizza temps are just about there. I need to get insulation on and then pizza! I probably could have done some pizza yesterday - I had the temps up to 700 degrees. Portions of the dome just started to turn white!

I wanted to post a few pictures of my front arch and vent area just to keep my thread up to date...

As you can see from the pictures of the front arch I decided not to cut tapers on these bricks. I cut tapers on every brick in this oven but decided I really need to get this done before the snow. I wasn't extremely pleased with my brick/mortar spacing of the front arch because I ended up with a mortar joint directly where the keystone should be. This arch won't be visible once I get my decorative arch in place and I don't believe this weakens the arch at all. A vent transition mortar/bricks bridge across thiss "keystone mortar joint" which should prevent it from cracking too.

My vent and vent transition came out pretty good. I thought I would need to go higher with the tapering of the bricks but this set-up draws really well! I need to mortar in my anchor plate and attach my chimney pipe. I ended up temporarily attaching a 12" pipe and a 36" inch pipe to the anchor plate just to see how this thing draws. Eventually there will be the 12" section mounted to the anchor plate then a 30 degree angled pipe then the 36" section and then another 30 degree angled pipe so the chimney pipe will be aligned with the center of my dome.

I started curing with a 100 watt light bulb for three or four days. It was amazing that this light bulb would keep the dome at around 90 degrees with a temporary door blocking the oven opening. I would cover the oven every night with plastic and in the morning would see mositure on the underside of the plastic. Then I started using an electric hot plate burner which kept the temperatures around 180 degrees for about four or five days until there was no moisture on the plastic. Then finally started my first fire!! I started off burning pizza boxes from inferior competitors . My wife is pregnant and craving pizza all the time so we have plenty of pizza boxes. I eventually moved onto small sticks and increased temperatures over the course of the week until I got to about 700 degrees. I couldn't let the fires go to waste so we took tomatoes and basil with EVOO from the garden and roasted them on a pan. They were pretty tasty but I'm not sure if I can give all the credit to the oven. How bad can garden tomatoes and basil really be even without a brick oven?? We also roasted some eggplant from the garden which came out really good too.

I'll be picking up my insulation tomorrow. I plan on using three inches of Fiberfrax DuraBlanket-S made by Unifrax. It's a ceramic woven blanket that can handle 2300 degrees Fahrenheit. The chemical composition is slightly different than the FB Blankets but I'm sure this will work fine. The FB Blankets just cost too much for me to ship from California to Connecticut - $40 per blanket. Once the blankets are in place I have a hipped-roof sheetmetal studded cement board enclosure built around everything. The space between the cement board and blankets will then be filled in with loose vermiculite. I don't plan on putting any cladding around the dome (under the blanket). The way I look at it is the hearth floor is just under 2.5" thick with plenty of insulation underneath it and the heat will be retained just fine here. The dome bricks are 4.5" thick so why do I need a cladding of one inch?? I hope it doesn't come back to bite me in the *ss but I don't think it will. Besides, my curing fires are just about done and if I add the cladding then I'll need to start the curing fires all over again.

Anyways...Sorry for rambling on so much but I haven't posted in quite some time and just wanted to get caught up.

~Bob

[pizza_bob]

Re: Pizza Bob's 42" Build

A few more pictures...

[dbhansen]

Re: Pizza Bob's 42" Build

Beautiful work, Bob! I bet that vent will draw really well. Congrats on the progress.

[pizza_bob]

Re: Pizza Bob's 42" Build

Thanks Darren,

What gauge metal did you use for your studs? Was it 25 or 20? I need to decide today on which to go with. I'll be hanging cement board with a stone veneer so I'm leaning towards the 20 gauge. These studs are aluminum?

~Bob

[dbhansen]

Re: Pizza Bob's 42" Build

I think I went with the heavier gauge (probably a good idea for a stone veneer). Mine were aluminum.

[pizza_bob]

Re: Pizza Bob's 42" Build

Thanks again Darren!

I contacted the manufacturer of the steel studs I'll be purchasing/using. I explained my project and they asked what is the weight of the stone veneer. I was able to find the data sheet for the Virginia Ledgestone veneer that I'll be using. The weight is 11.6 lbs per square foot. I calculated the square feet of my enclosure and the stone weight alone, excluding the cement board and scratch coat, is approximately 2200 lbs!! I never imagined the veneer stone would be that much! So their engineering department reviewed the drawings I sent them and they ran some calculations for me and determined I should use the 18 gauge studs. These studs are .0451" thick. The steel studs are from Marino\WARE - metal framing systems, lightweight steel framing for commercial and residential buildings.. Their technical services group was great! They replied immediately with an answer after I sent them my drawings. I attached a JPG for my stone veneer and the structural catalog from Marino-Ware can be found at this link:

http://www.marinoware.com/Documents/2009%20MW%20CFS%20Catalog.pdf

They recommended I use 358SW18 stud and space them 16? on center. They also recommended the screws that I should use: (4)#10-16 screws.

This thing should be framed by next week. I'm having someone else do this for me...

~Bob

[pizza_bob]

Re: Pizza Bob's 42" Build

I got my insulation on yesterday. Three blankets of Unifrax DuraBlanket. All of the dome is covered with at least three inches of blanket and some overlapping areas have four inches. I used boiler strapping and TapCon screws to hold the insulation in place until my enclosure is complete. Once the enclosure walls are up I'll fill the rest of the area with loose vermiculite. How many times have we heard the phrase "You can not over insulate!"? Well I have researched this so much that I finally stumbled across information that says "too much insulation starts to work against you"! It seemed so counter-intuitive at first but once you look at the equations for heat transfer it actually makes sense! When insulating circular or spherical objects the surface area increases which increases convective heat transfer (heat loss). By adding three inches of insulation to a 42" oven the surface area increases approximately 23%. This increase in surface area increases the heat loss. The equation for convective heat transfer is:
q = k A dT
where
q = heat transferred per unit time
A = heat transfer area of the surface
k = convective heat transfer coefficient of the process
dT = temperature difference between the dome and outside air

You can se that as the area increases so does the heat loss. The thickness of the insulation does not play a role in convective heat transfer.

But the thickness of insulation does minimize conductive heat transfer. The equation for conductive heat transfer is:
q = k A dT / s
where
A = heat transfer area
k = thermal conductivity of the material
dT = temperature difference across the material
s = material thickness

From this equation you can see that insulation thickness does minimize heat loss because the thickness (s) is the denominator. So as the thickness increases the heat loss decreases but....Area is also part of this equation which works against you in conduction too.
It gets to be a balancing act between surface area vs. thickness that results in a point of diminishing returns. I'm sure I didn't do the best job explaining this but Google "critical thickness of insulation" if you're interested for better explanation. Here is a link that might help too:
Critical Radius of Insulation

This caught my interest and I thought it might be worth sharing. So sorry for be long winded.

I did insulate my dome and it seems to work well. I had the fire at 900 degrees Fahrenheit for a couple hours, cooked my first pizza in 2.5 minutes and then pulled the coals out. I then left the oven open with no door for four hours before i had to go to sleep. So I put a piece of particle board that I had used for my inner arch across the doorway overnight. It doesn't fit well so it leaks all around and it's really thin. The temps dropped down to mid 40's last night and my oven dome was still 375 degrees and the floor was 350 at noon the next day. I thought that was pretty good for 4 hours of no door and twelve hours with a particle board door. The concrete under the hearth (ceiling of the wood storage area) was 73 degrees at noon and outdoor temperatures were around 60 degrees.

Anyway...Here are some pics of the insulation process. I'll follow this up with pizza pictures.

~Bob

[pizza_bob]

Re: Pizza Bob's 42" Build

Here are some pictures of my first pizza. The dome was completely black but quickly cleaned up when temps hit 900 degreess. It's nice to see the dome back to its original color after all these curing fires. The pizza was just mozzarella, sauce and fresh basil from the garden. I was surprised I didn't burn the bottom. The pizza cooked in 2.5 minutes with the dome at 750 degrees Fahrenheit and the floor at 650. Immediatley after removing the pizza I measured the floor to be 630. I hope I don't regret not having more thermal mass and insulation under the floor. The insulation under the floor really seems to work well because there really isn't much temperature rise hours after firing in the wood storage area ceiling. Is one layer of bricks really enough thermal mass to get say 12 pizzas cooked without having to recharge the floor? I have 2.250" inches of vermicrete (mixed 5:1 ratio) sitting on top of 2.00 inches of FoamGlas. The FomaGlas really is a great insulator but I wonder if I should have gone thicker with that and/or the vermicrete. I'll find out this weekend when I try to make more than two pizzas...

~Bob