Thermal break between dome and chimney box

[christo]

I've poked around the site and did not find much on this subject. Or I looked in all the wrong places....

It seems like a pretty big heat sink is attached at the front (or back) of many ovens in the form of an un-insulated chimney.

Has any one used extra insulfrax or other insulation to thermally isolate the chimney similar to the floating hearth concept? Does the general consensus think it will make a reasonable difference in heat retention?

Thanks

Christo

[dmun]

Most people use triple wall engineered flues for their ovens, which have a LOT of insulation between the inside and the outside. They are designed to withstand a chimney fire of highly flamable creosote without setting the house on fire (you see a lot of them installed in a wood frame riser).

Even masonry chimneys are supposed to have a half inch of free air space for insulation between the refractory flue tile and the four inches of masonry surrounding it.

So yes, the chimneys are supposed to be insulated.

[christo]

I'm not doing very well communicating my question.

I'm asking if it makes sense to break the oven in half and provide separation between the oven half and the pizza entry tunnel (piehole) that supports the chimneys on most ovens.

Sort of an addendum to the island hearth discussion - breaking more of the oven off and isolating it.

In most ovens I've seen here, the pie hole and chimney support extend about 16 inches from the opening in the dome. That seems like a lot of masonry (even if you exclude a triple wall chimney duct) that could suck heat from the dome. There is also extra flooring bricks that could pull heat from the floor.

I was considering leaving a 1 inch gap at top, bottom and sides around the dome opening and filling it with castable refractory insulation after I build the chimney section.

I guess the real question here - do oven entrys feel warm to the touch, does the floor of the oven entry pull significant heat from the oven floor?

As always, Thanks!!!

Christo

[maver]

The oven entry feels warm, but per our fireplace discussion, remember that there is radiant heat from the oven glowing through the entry. Perhaps an engineer could answer the question whether the heat conducting from the oven into the masonry of the landing area and chimney vent areas is significant compared with radiant heat loss and convection (cold air entering through the opening). From the practical standpoint, I doubt you have much to gain here from the pizza making standpoint. The real question would be whether this improves retained heat baking.