Intro

[wg_bent]

Hi Guys. New to the forum here. I spend a LOT of time over on the Hearth forums, and building a wood burning oven is an natural extension of heating with wood. I'm wondering why sand on top of the dome isn't added as an insulator/mass, plus expansion layer.

[james]

Re: Intro

Welcome aboard,
I am guessing that a lot of what you have learned in the "hearth" world will be applicable in the wood-fired "oven" world. It will be interesting hearing about your experiences and where you see overlap, and where there are differences.

For a wood-fired oven, sand sort of falls into a no-man's land. It is not as efficient as refractory bricks and pre-cast pizza ovens, or even refractory mortar -- so it is not really something that you would want to add to build up thermal mass, or heat holding capabililty. At the same time, it is definitely not a good insulator. It tends to wick heat away from the oven, rather than blocking it and holding it in the oven.

I think of sand as an infinite sink -- which has its place in other thermal applications, but not really in a pizza oven. It's been replaced by the high tech stuff.

For expansion, a wood-fired oven is surrounded by insulation on all sides, but none of it is binding in any way -- so the oven has lots of room for expansion and contraction.

Again -- welcome to the group. It's a good bunch of people, and I think we are all interested in learning from your experiences.
James

[wg_bent]

Re: Intro

It's my belief that Masonry heaters are pretty similar to brick ovens with the exception that they are less efficient heaters.

My expertise is largely in wood stoves and I can tell you about the characteristics of most of the stoves on the market. Stoves are built for wood efficiency and max BTU's out of the wood and how they distribute heat are the key points. With a wood oven it seams that the goal is to contain the heat as best as possible.

Interesting about the sand... I'll skip that thought. I was perhaps going to build a temp oven out of a precast oven roof and use loose bricks for sides back and front. Sand would be used to sort of seal the outside. After thinking about it, it seems just as easy to build a permanent one.

BTW, are firebricks necessary for the floor? Why not heat tolerant concrete for the floor? another one, if using cinderblocks for the base, what's best option for the bottom of the concrete slab pour? I was thinking of durock. If I used durock with a bunch of vermiculite with heat tolerant concrete over that? Just the opposite of the dome sort of.

[Dutchoven]

Re: Intro

Durock is certainly OK IMHO. I have seen lots of options. My barrel vault ws just a free pour on a form. First a strutctural layer about 4 inches then an insulating layer of perlcrete of about 2 inches. Oven is over two years old and other than some heat seepage very late there have been no problems...knocking on wood.
Hey theres a thread in the Newbie forum that you might be able to shed some light into given your experience with masonry and wood stove heating. It is about ovens being a significant source of pollution. I answered speaking about secondary combustion but you probably know more than I.
Best
Dutch