Hearth Design

[Freddie]

My oven will be used mostly for pizzas - maybe bread on occasion, but not too often. I read the Bread Builders book and was going to build that type of a brick oven until I found this site. I'm now getting ready to build my brick oven using the plans from this web site, but there are some features on the other plan that I want to incorporate in my brick oven.

One is the ash slot. The bread builders design allows a slot at the back of the landing to catch hot ashes raked out from the oven. The design from this web site does not show such a thing and I can't find any threads discussing this. Is there a drawback to putting an ash slot in the landing area?

Also, the bread builders design has the hearth floating. Rebar inside the hearth rests on the stand blocks and supports the hearth. The hearth cement itself does not touch the stand. Is this an advantage or disadvantage to this type of hearth?

Any help you can give me on this would be greatly appreciated.

[james]

Re: Hearth Design

Hey Freddie,

Welcome aboard. I move this thread to Getting Start -- I think you will get more input here.

Good questions. I've built the hanging hearth a couple of times, and don't recommend it (strongly). It is difficult to build and the long term reliability is questionable. One of the reasons it was designed that way was to accommodate a thermal layer of concrete directly below the oven cooking floor -- which is something you definitely do not want to do. It is easier and much better for cooking performance to pour a concrete hearth directly on the block stand and then install a layer of insulation directly under the oven cooking floor. That's easy!

There is at least one good thread on whether the ash slot is useful -- a number of folks have built it into their Pompeii oven.

Enjoy!
James

[Jed]

Re: Hearth Design

Hey Freddie,

I decided against the ash slot for this reason. When I remove the ash from the oven, I can scoop it out of the oven with a small shovel / dust pan then place the ash into a metal bucket. If I were to let the ash fall the distance from the hearth to the bucket, the dust cloud would be noticeable, and send ash billowing over a wide area. I didn't want to spread the mess, and it is controllable to scoop the ash from the oven minimizing the mess. Personal choice... either way works...

JED

[Freddie]

Re: Hearth Design

Thanks for the info. I hope to get started on the foundation soon - as soon as it dries outside.

[dmun]

Re: Hearth Design

The barrel vault oven is primarily a bread oven, and the fire gets raked out of the oven while it is still burning, to use retained heat baking. With an ash slot you aren't balancing shovels full of burning coals on the way to the ash bucket.

A lot of us use our ovens mostly for pizza, and the fire just burns down by it's self, leaving only a shovel or two of loose ash to remove the next day. A high mass oven may require much larger fires and more ash removal. There is also the small matter of having an ash slot directly below the oven entry, things can fall in it, and it reduces the space available for wood storage.

I've had an idea for having a covered recess at the oven opening that could be used with a tuscan grill for barbeques, and have an angled ash slot off to one side, that wouldn't interfere with the wood storage door. This does involve rather baroque bricklaying and might be more than a beginning builder might want to undertake.

[Neil2]

Re: Hearth Design

"Is there a drawback to putting an ash slot in the landing area?"

I put a 1 inch wide by the full width of the door ash slot in mine. This tapers into a 4 in diameter opening in the structural slab. An ash slot like this also serves as a thermal break between the hearth and the landing.

[DrakeRemoray]

Re: Hearth Design

Here are a few threads on the ash slot.

I do a lot of baking and do not have an ash slot and do not miss it. I think it would mostly get in the way.

http://www.fornobravo.com/forum/f14/ash-dump-4505.html
http://www.fornobravo.com/forum/f6/ash-slot-3846.html

Drake