Shep's Oven Firing Firing Your Oven Discuss Shep's Oven Firing in the Oven Management forums; Originally Posted by RTflorida Although not the best choice for maximum BTUs, poplar should burn plenty hot to go beyond ...

[Barry Shepherd]

Originally Posted by RTflorida

Although not the best choice for maximum BTUs, poplar should burn plenty hot to go beyond 700 degrees. The build a bigger fire mantra holds true; as I was originally told - build a scary fire, if you don't step back and say "holy crap", it needs more wood.
My only question - you mention dome insulation and it sounds like you are good there; what about under the hearth?

RT

R.T.
I have 3in. of refactory cement and a layer of silver foil under the hearth. After your advice about a HOLY CRAP fire i think that might be my problem,yet when i put my hand on top of the insulated dome it is too hot to leave my hand there, I read somewhere that it should only be warm. I have about 3 to 4 inches of vermiculite mixed wit concrete in top of the dome. I have 3/8 P2000 insulation over the vermiculite it only gets warm. If I get it up to 700 degrees how long should i keep it fired at that temp.? And how long after i remove the fire should it retain temps of 250 to 300 degrees.

Thanks for your interest
Shep

[james]

Shep,

You should download the FB Wood-Fired Cooking eBook. It has lots of graphics and descriptions of how to fire and manage your oven. I think that will take a lot of the mystery out of it.

One the enclosure heat, it is possible that you are still driving moisture out of the mortars and insulation. That moisture makes the enclosure walls warm as it leaves the oven. After a series of fires, the inside of the oven gets hotter and the enclosure cools down.

Check out the eBook. It's free on the FB Store.
James

[dmun]

I have 3in. of refactory cement and a layer of silver foil under the hearth

Is that a lightweight insulating refractory product, or a heavy solid product? You may have an uninsulated hearth floor, which will give you no end of trouble. Aluminum foil doesn't do much: the caustic masonry products rot it out pretty quickly.

[Barry Shepherd]

DMUN

Here is what I have in my hearth floor. 1st I have 2 in. fire brick, a layer silver foal, then 3 to 4 inches of refactory concrete, and finally 3 inches of regular concrete as the top of my base.

Thanks
Shep

[dmun]

3 to 4 inches of refactory concrete

There are literally hundreds of castable refractory products. I don't know what's under your floor. What I'm getting at is whether you have any insulation under there. If not, it's going to be hard to get your oven up to temperature no matter what you burn, or how long.

I wish I could say this is an unusual situation. We hear about many ovens built with no insulation or bad insulation (sand, gravel, broken glass) under the floor. There's no satisfactory fix to this problem.

[james]

Even if you have solid refractory under the floor, you can wrestle your way through it. Shep, first thing is to fully get your oven up to temperature and get some serious heat and bake some great pizza. 750F minimum. Go for it, and see how it does.

The biggest problem with an uninsulated floor is that it will be more difficult to keep the floor at pizza temperature when you make a series of pizzas in a row. But first things first. I've been there with the uninsulated floor (my Scott oven had 9" of brick and concrete for the floor), and there are ways of working around the floor problem.

Let us know how it goes.
James

[sacco]

Will 2 inches of refractory cement "Mizzou" provide sufficient insulation for the hearth base.

[dmun]

Will 2 inches of refractory cement "Mizzou" provide sufficient insulation for the hearth base.

Mizzou castable plus does not seem to have any insulating properties. The linked page stresses resistance to spalling and slag penetration, which would more of a solid product.

[Barry Shepherd]

Thanks for all your help, I think that i have solved my problem, After building a (holy Crap Fire) I have no problem, I was afraid to build a hot enough fire. Thanks again, By the way about 3 weeks ago i ordered a cook book from Forno Bravo, I have not recieved any contact from them, what is the customary delivery time table?

Bye for now

Barry Shepherd