Pompeii Oven Insulation

[Bubazineti]

Hi all,

I am nearing the end of my build.

Over the dome I have 1in Kaowool ceramic blanket held on with chicken wire. On top of that I have 2 to 3 inches of high heat mortar. Against my better judgement I didn't add 4" of vermiculite around the blanket and am worried that I have insufficient insulation.

I am located in Queensland, Australia so apart from a couple of months in the year it is pretty warm.

Having spent so long the last thing I want is it not to function properly so my question to those in the know is will this be enough or should I invest in another layer of blanket or (shudder) 4" of vermiculite. The finish on the high heat mortar is pretty close to perfect - it just needs a layer of stucco / render. If I can get away with what I have it would save a lot of dollars on blanket and more high heat mortar.

Thanks in advance,
Luke.

[REE REE B]

Re: Pompeii Oven Insulation

Hi Luke

Your Ceramic Insulation blanket is enough so no worries at all.

Enjoy finishing off your oven

[moderator]

Re: Pompeii Oven Insulation

Hi Luke,

Thank you for your question. We recommend 3" of the insulating blanket covering the dome. When insulating your pizza oven you either, use the insulating blanket or vermiculite, not both. If you have anymore questions... ask away!

Amber

[REE REE B]

Re: Pompeii Oven Insulation

Hi Luke

Do you have the Pompeii 90 or 110 kit? The Pomeii 90 kit requires 2 blankets and the Pompeii 110 requires 3 blankets. So you may just need one more blanket to finish the job.

[Bubazineti]

Re: Pompeii Oven Insulation

Hi guys,

I'm actually not using a kit. I used the pompeii oven instructions but interpreted them as either blanket or 4" vermiculite. On rereading them and looking at other forum posts i'm concerned I should have added more insulation.
The oven is 42" internal.
Dome is constructed using half firebricks with high heat mortar.
Wrapped in 4m of kaowool s and 2m of a better blend of kaowool.
2-3"of high heat mortar to form the dome.

On coming back from work today it turns out the father-in-law has been a bull at a gate and put a fire on despite me only mortaring on Sunday. It's a medium size fire - much hotter than it should have been for a first burn and its put a split in the mortar covering the arch in front of the chimney. This part is warm to the touch.

The front part of the dome behind the chimney is slightly warm to the touch (where the kaowool s is) and the top and rear is cold (where I put the higher quality kaowool).

So i'm going to have to do a repair job to the arch mortar and maybe add some insulation to it as I didn't have enough to cover the front 8" in front of the chimney.

Hope this makes sense.

Cheers,
Luke.

Edit
My wife has suggested that the heat may be coming from the chimney. The inside of the door arch is made of curved iron with a welded chimney so this must be getting superheated and possibly radiating out and heating the high heat mortar on the surface. Just an idea.

[brickie in oz]

Re: Pompeii Oven Insulation

High heat mortar isnt insulation.

[Bubazineti]

Re: Pompeii Oven Insulation

Hi brickie,

Yep i'm aware of that. The question was whether 1" of ceramic blanket is enough.
The cerachem 1430 (better quality ceramic fibre) seems to stop the heat getting to the exterior with the fire today (though I haven't done a full strength fire yet) while the kaowool s is letting a lot of heat through.

So I guess the reality is (unless the heat is radiating from the metal chimney through the surface mortar) I need to put another layer of cerachem 1430 on and make sure I insulate the arch (another 6m at $30/m ).

Cheers,
Luke.

[dottavio]

Re: Pompeii Oven Insulation

Not sure which version of the Pompeii instructions you have, but it calls for 3" of ceramic blanket or 1" cermanic blanet with 4" insulating (perlite or vermiculite) concrete.

Doug O

[Faz]

Re: Pompeii Oven Insulation

You will get some extra heat dissipation during your drying fires, as the steam will carry heat from the bricks through to the outer covering. I do not think, however, that 1" of blanket is anywhere near enough insulation, especially as you have built in a huge heat sink with the 3" layer of mortar on the exterior. Heartbreaking as it may be, I'd recommend stripping off that external layer and adding more insulation (blanket or vermicrete), otherwise you'll struggle to maintain any temperature in the oven.

[Bubazineti]

Re: Pompeii Oven Insulation

That is bad news - you don't think i'd get away with just laying some more insulation over the fireclay?

Think i'll have to go vermiculite even though it's a nightmare to use. 2 more layers of ceramic blanket would be $400. I shudder to think how much this has cost to this point. Should have stuck to my guns and done it in the first place. While i'm about it going to cut out the iron flue and put in a stainless 8" (if I can find one).

[Faz]

Re: Pompeii Oven Insulation

The trouble with putting insulation over the 3 inch layer is that it is isolated from the internal brickwork, so any heat sitting making its way to this layer will not be usable.

See what other people think before hacking it off, as others may disagree!

[david s]

Re: Pompeii Oven Insulation

I don't think you should do anything drastic and make changes. Why not continue to fire the beast and see how it works. It will take around 10 decent fires before you have really purged it of moisture. See how it performs. You might find that it does not hold heat as well as it may, but do you need to have it retain cooking temp for the next few days? You can always get into it with a bit more fire. Breaking up the outer shell to add more insulation then redoing the outer shell is a lot of extra work.

[Bubazineti]

Re: Pompeii Oven Insulation

Hi guys,

As you say David i'm going to see how it goes. Only way to be sure. As long as it stays hot for a few hours i'm happy. Will let you know how it performs.

Thanks for all your help.

[brickie in oz]

Re: Pompeii Oven Insulation

As long as it stays hot for a few hours i'm happy.

For the same money it should stay hot for days, not hours.

[sturoofer]

Re: Pompeii Oven Insulation

What happened with the fire? I have exactly the same problem. Built my pizza oven from scratch, done a big one with fire bricks for the floor on vermiculite mixed with mortar sitting on PU insulation. Clay bricks for the dome, with just one inch of ceramic insulation covering it. Then chicken wire and around 1" of mortar to a nice smooth finish. Just lit my first fire today, kept it going for about half an hour then let it die out. I could barely touch the dome it was so hot! By the time i come to have a proper fire in there I could be using the dome for frying eggs on. Thinking about it at length, I think for the purpose it was built (cooking lots of pizzas) it will be fine, I will just have to have a bit of flame going on I think to keep the heat in there. If I want it to stay hot for days though, I think I would cut some 2" x 1" timber every few inches almost all the way through, and fix this over the dome (like rafters) Then stretch some Multi layer silver insulation (Tri Iso Super 10 or TLX silver) over the battens, then fix more battens over the TLX insulation. Then hardboard, then chicken wire and more render to finish. A bit of a rigmarole, and I could kick myself I didn't do it right to start with, but there you go, I have come too far to not do it right!