gt40's Pompeii Oven 42" build log

[shuboyje]

Re: gt40's Pompeii Oven 42" build log

I hope your chain holds up better then my stainless cable did. I just finished demolition on the old oven and was very disappointed to see the status of the cable. All there broke clean at the same spot, must be the result of some uneven thermal expansion. Even then the remaining cable was corroded stretched and brittle. Oddly enough my 16 gauge black iron vent was in perfect condition as was the angle iron that framed the door and connected the cable together. Live and learn. Luckily I was already planning on using multiple methods on the new oven and am confident it will be fine.

[gt40]

Re: gt40's Pompeii Oven 42" build log

What you are building is very similar to the traditional vent on ovens built in Naples. They claim an experienced oven builder can tell when the flue is not constructed this way just from watching the oven fire. I guess you and I will both know soon enough how well it works. I have my old oven with a straight up vent to compare it to.

Last point is that I would consider a additional chain of bricks at the front if it fits your enclosure. It will create more of a smoke chamber and better airflow which should lessen the amount of smoke that goes out the front on startup. The traditional vents are very high in front and I assume this is the reason why.

I am taking your advice and putting a second row on front and the whole channel half brick height to increase volume

You could always incorporate a damper into the front of the flue to shut it off.

Any suggestions on design?

[brickie in oz]

Re: gt40's Pompeii Oven 42" build log

I hadn't thought much about the channel sucking air through it

You could always incorporate a damper into the front of the flue to shut it off.

[shuboyje]

Re: gt40's Pompeii Oven 42" build log

What you are building is very similar to the traditional vent on ovens built in Naples. They claim an experienced oven builder can tell when the flue is not constructed this way just from watching the oven fire. I guess you and I will both know soon enough how well it works. I have my old oven with a straight up vent to compare it to.

Last point is that I would consider a additional chain of bricks at the front if it fits your enclosure. It will create more of a smoke chamber and better airflow which should lessen the amount of smoke that goes out the front on startup. The traditional vents are very high in front and I assume this is the reason why.

[gt40]

Re: gt40's Pompeii Oven 42" build log

"I was actually thinking the super heated gases recirculating over part of the dome would be more efficient and better than sending them straight up and out. I will wrap everything in fiber blanket in any case."

Yes, this would be so, but once the fire is out and your door is on for roasting or baking, cool air is going up your flue over the uninsulated dome. In the usual set up it doesn't matter if the flue is cooling because it is isolated from the actual oven.[/QUOTE]

Your point is interesting. This stuff is more complicated than it seems. I am not an engineer or anything but I was thinking that the whole flue channel and bottom part of the chimney wrapped in fiber blanket would give enough insulation + the chamber would be sealed with the door.



I hadn't thought much about the channel sucking air through it and cooling the dome through the unexposed portion. Unless I have a fan blowing air through the channel with the door closed, I am hoping the insulation on top of the channel will do its part. I will finish building it and report back before I permanently enclose my dome. I can always convert it to a traditional chimney.

On the other hand, this design may provide increased draw and faster heat up times

Pic so far:

[david s]

Re: gt40's Pompeii Oven 42" build log

"I was actually thinking the super heated gases recirculating over part of the dome would be more efficient and better than sending them straight up and out. I will wrap everything in fiber blanket in any case."[/QUOTE]

Yes, this would be so, but once the fire is out and your door is on for roasting or baking, cool air is going up your flue over the uninsulated dome. In the usual set up it doesn't matter if the flue is cooling because it is isolated from the actual oven.

[gt40]

Re: gt40's Pompeii Oven 42" build log

Without a specialized coating I think board is a poor choice for the top of your vent. It will be in contact with fire and moisture laden corrosive flue gases. I'm building a similar vent(eventually) on my new oven and will be using either a dense castable or pieces cut out of a flue liner for this.

Interesting point. I was going to coat the fiberboard with refactory paste. I will look into the durability of the fiber board. I may just put a plate of 321 stainless on the top and then put the fiber board on top of that.

I'd be concerned about the heat loss from the top of your dome into the flue area when doing retained heat cooking. Wouldn"t it be better to insulate over the dome first, then run your flue over the top of the insulation.

I was actually thinking the super heated gases recirculating over part of the dome would be more efficient and better than sending them straight up and out. I will wrap everything in fiber blanket in any case.

[david s]

Re: gt40's Pompeii Oven 42" build log

I'd be concerned about the heat loss from the top of your dome into the flue area when doing retained heat cooking. Wouldn"t it be better to insulate over the dome first, then run your flue over the top of the insulation.

[shuboyje]

Re: gt40's Pompeii Oven 42" build log

Without a specialized coating I think board is a poor choice for the top of your vent. It will be in contact with fire and moisture laden corrosive flue gases. I'm building a similar vent(eventually) on my new oven and will be using either a dense castable or pieces cut out of a flue liner for this.

[chidding]

Re: gt40's Pompeii Oven 42" build log

Wow thats different, but something im very keen to see the outcome. Dome looks amazing! keep us posted

[gt40]

Re: gt40's Pompeii Oven 42" build log

Great job gt40! I really like the chimney work (and the whole chain idea). Maybe you have a little grandchild/neighbor you could use pizza IOU's to bribe them to clean the inside for you . Worth a try. Looking forward to the rest of your build...

gene

Thanks for the encouragement


I went to do some more chimney work and found I have about 35 more bricks so I decided to make a flue channel go from the front to the top. I will build a little box on top of the dome where the chimney pipe will go.

Pics of the dry fit:






the roof of the channel will be ceramic fiber board...

[ggoose]

Re: gt40's Pompeii Oven 42" build log

Great job gt40! I really like the chimney work (and the whole chain idea). Maybe you have a little grandchild/neighbor you could use pizza IOU's to bribe them to clean the inside for you . Worth a try. Looking forward to the rest of your build...

gene

[gt40]

Re: gt40's Pompeii Oven 42" build log

Update:

I am pleased to have finally finished building my first brick dome. I have to finish the chimney but the dome is very solid. I sat on top of it and is feels like it isn't going anywhere.

Finished oven dimensions:

49"/1244mm diameter floor

17.5"/444mm oven interior height

door opening: 18"/457mm x 11.5"/292mm tall.

3.5" soft firebrick/ceramic fiber board insulation under the floor

I really wished I had the patience to clean the inside better but at this point it is hard to work inside of there.

Here are a few pics:
top:


inside:


chimney top so far:



business end:


Thanks for looking

[benguilford]

Re: gt40's Pompeii Oven 42" build log

I love what you've done there, particularly how you've set the first layer of insulating firebrick into the hearth slab. Very cool (no pun intended). Now wishing I had done the same!

[gt40]

Re: gt40's Pompeii Oven 42" build log

Your build is looking good gt40. The chain is a unique addition. Did you sink the bolts that supports the brackets all the way down into the hearth, or just into the vermicrete? Too bad you have to cover it with insulation; the chain would be a great conversation piece .

gene

Thank you for your comments. I wish I could show the chain! In answer to your question, I didn't use vermicrete.

The foundation is 4"/101.6 of high psi concrete. I sunk the anchors deep into the upper cement.

On top of that where the oven is I have a bed of 2.5"/63.5mm thick soft firebricks. Above the soft firebricks is 1"/25.4mm thick ceramic fiberboard insulation for a total of 3.5"/88.89mm of insulating material. Then I had them pour concrete up to the top of the insulating bricks so it was flush.

Here is a pic:



On another note, I had hoped to finish today but got sidetracked and only got to make one course. It is getting interesting at this point and I built my first row standing outside the oven compared with always standing inside.