Insulated Hearth

[Howie]

I'm getting ready to pour the insulated hearth for the Premio 120 Modular Oven. This is turning into a real scavenger hunt. I notice that the insulated hearth is poured using Calcium Aluminate Cenent to create refractoty concrete. Altrnatively regular concrete. Will the regular concrete hold up? Or should I go the distance and use the Refractory Concrete?

TIA

Howie

[james]

Hi Howie,

I think you really only need Calcium Aluminate concrete in a commercial oven that is fired 24-hours a day. A large percentage of home ovens are installed using standard concrete (in fact there are installation guides from producers that recommend a simple, standard concrete hearth without any insulation). If you have an easy, local source and it isn't expensive, you could go for the calcium aluminate, as it will last longer (probably long after we are all gone) and perhaps heat up a little faster, but the difference is not worth a lot of effort.

James

[aikitarik]

Would this be true for the Pompeii as well? I do have an inexpensive and easy source of this concrete (and mortar) and was already planning on purchasing it for the oven build.

It never occurred to me to use it in pouring the hearth. I'm planning on trying to do the island hearth, BTW, which seems slightly challenging since I have to pour the island while the perlite insulative layer is still wet, which means removing the island forms. Time will be important.

Tarik

[paulages]

if you are already pouring an adequate support layer as described in the other thread about the island hearth, i believe you could just make a circular form out of sheet metal to separate the thermal concrete from the surrounding perlite layer, and just leave the metal form in the concrete. i would set in a half inch or so beneath the surface.

[aikitarik]

Logical... dunno why I didn't think of it! :-)

I was not planning on pouring an extra support layer.

The back 2/3's of the oven hearth will be supported by sitting on a 6+ inch poured concrete foundation poured behind a 3 foot high, 6-7 inch thick concrete retaining wall.

Only the front 32 inches will be supported by concrete blocks as in the normal design. I am reasonably confident that I don't need the concrete layer under the insulation layer for this as this would only be supporting the throat of the oven.

Let me know if you think otherwise.

Tarik

[ColonelCorn76]

Originally Posted by aikitarik

Logical... dunno why I didn't think of it! :-)

How do you think I feel?