Questions Re Attaching Terracotta Flue

[Behen]

After a long layoff building our pompeii 42 oven we're finally getting back at it. When we stopped our dome was complete and we're now getting ready to complete the archway outside the dome and attach the terra-cotta flue to the vent opening. After that we'll insulate w/ FB blanket and some vermiculite concrete and top it off with waterproof stucco in igloo form. Our first question is when attaching the very heavy flue to the vent opening should the rectangular flue be parallel or perpendicular to the oven door or doesn't it matter. Second, when attaching the flue how much of it should sit on the vent bricks, a half inch or more? I'm very worried about the weight of the flue on the arch. Is there an additional way to support the arch so that it can support the flue? Should a course of fire bricks be mortered to the bottom of the flue? I read in the pompeii instructions that the flue can't be "attached" to allow for expansion of the flue during fireing of the oven. So how exactly does one secure the flue?I've attached a few photos of the oven. Next, I was wondering what if any affect the weather over the past year has had on the oven dome. We left it uncovered while we waited to get back to working on the project. We live in Delaware so it's been exposed to a few snow storms and rain. It was covered with a layer of refractory cement. Any ideas? I was wondering if once we finish the oven opening vent and attach the flue should we build a small low fire in it prior to insulating to see if any smoke comes through the dome to indicate a crack. Thanks for any help or ideas.

[Laurentius]

Re: Questions Re Attaching Terracotta Flue

Hi Behen,

That is huge. When I saw the oven the old adage came to mind. " A rolling stone gather no moss". Why not start making a small fire to drive some of the moisture out?

[stonecutter]

Re: Questions Re Attaching Terracotta Flue

After a long layoff building our pompeii 42 oven we're finally getting back at it. When we stopped our dome was complete and we're now getting ready to complete the archway outside the dome and attach the terra-cotta flue to the vent opening. After that we'll insulate w/ FB blanket and some vermiculite concrete and top it off with waterproof stucco in igloo form. Our first question is when attaching the very heavy flue to the vent opening should the rectangular flue be parallel or perpendicular to the oven door or doesn't it matter. Second, when attaching the flue how much of it should sit on the vent bricks, a half inch or more? I'm very worried about the weight of the flue on the arch. Is there an additional way to support the arch so that it can support the flue? Should a course of fire bricks be mortered to the bottom of the flue? I read in the pompeii instructions that the flue can't be "attached" to allow for expansion of the flue during fireing of the oven. So how exactly does one secure the flue?I've attached a few photos of the oven. Next, I was wondering what if any affect the weather over the past year has had on the oven dome. We left it uncovered while we waited to get back to working on the project. We live in Delaware so it's been exposed to a few snow storms and rain. It was covered with a layer of refractory cement. Any ideas? I was wondering if once we finish the oven opening vent and attach the flue should we build a small low fire in it prior to insulating to see if any smoke comes through the dome to indicate a crack. Thanks for any help or ideas.

To your questions..

1) Your flue is oriented correctly...parallel with the front of your opening.

2) Make a stiff mortar mix ( same ratio as your build or use pre mix) but drier consistency. If you make it like brick mud, it wont have enough body to support it well.

3) Impossible to see any damage from the pictures. But I would assume that it is fully saturated if left uncovered all this time. Better to treat this like a new oven and slowly drive out the moisture.

One thing though. Your arch won't support more than one flue section without some buttressing on the sides. And don't lay your springer brick on edge like that.

[Behen]

Re: Questions Re Attaching Terracotta Flue

Stoncutter, Thanks for the tips. We decided to do away with an arch and just got straight across for the vent. We'll make an arch in front once the flue is in place. We also decided to put in some metal supports to help hold up the flue. I've attached a photo. Once we have the flue in place we're thinking about builing up a chimney around it out of regular bricks. Hopefully this will all work well. After a long layoff from the build we're ready to get the job done and enjoy some pizza! One question, is it necessary to insulate around the vent area in addition to the dome? Thanks again for your help.

[stonecutter]

Re: Questions Re Attaching Terracotta Flue

You don't really need to insulate around the vent...but it will keep heat from leaching out. Whether that is enough to effect draw, I seriously doubt it, but if insulating the vent doesn't effect your finishes in a big way, then why not.

I happen to insulate everything..even the flue up to where it passes through the roof to the chimney.