Insulating the inner arch from the oven.

[OscarA]

I have read a few post where some oven builds have an air gap so the inner arch is only partially touching the oven opening/landing. This is done to reduce heat lose, what I want to know is how necessary is it.
I realise it'll probably depend on what you want from your oven so for me it'll be pizza for lunch, roast in the evening and baking bread later that night or next morning. I don't need 3-5 days of heat.
I don't want to stuff this up so apologies for all the nubie questions.
So who has done it and who hasn't.

[lwood]

Hi Oscar,
I think you are talking about a heat stop where there is a gap btw the hearth and the landing outside the oven. The answer is no you don't need it. It provides another form of insulation at the door opening so the hearth heat doesn't conduct heat out of the oven into the landing. Most people don't have them.

[Neil2]

"This is done to reduce heat lose, "

Also keeps the heat of your landing down.

[OscarA]

Thanks for the reply my gut feeling was most builds didn't have them as there is so little mention of it.
This was the post that brought it to my attention http://www.fornobravo.com/forum/f8/h...lan-14389.html (Heat break plan)

After reading this I started toying with the idea of doing something similar but then started thinking if it's not really needed better to keep it simple.

[Neil2]

My 1 inch thermal break gap doubles as my ash drop. This is at the bottom of course. The sides and top are isolated using insulating brick.

[david s]

I have a gap on mine which is filled with vermicrete which is somewhat flexible and insulating. It's my belief that as well as the heat loss through conduction, it provides protection from the outer arch cracking due to firstly the pressure created on the outer arch by the expanding inner oven parts and secondly reduces the temperature differential on the inner and outer faces of the outer arch. It also leaves your outer arch only warm to the touch making it safer. These problems are both contributors of cracks in the outer arch. This gap is something that Rado Hand recommends and where I learnt it. Thumbnail attached for explanation.

[ThermoJax]

My inner arch is not touching the vent landing (floor) or the walls. I built mine so that a home depot paint stir stick, the big one for 5 gallons, would slide easily between the inner arch and the vent walls/chimney. I then filled that gap with some of the same high heat insulation blanket torn in pieces and shoved in there from both sides. Then, so I didn't have to look at it forever, I ran a bead of mortar down that gap from the inside. My vent floor only touches the oven floor at the very top, as was suggested by a senior member here. Does it help? Who knows? This is the only oven I have worked, and I have just finished mine not so long ago. I am glad I did the extra work though.

Good Luck...

[OscarA]

Thanks again guys the help this site offers is just great and really appreciated.

I built mine so that a home depot paint stir stick, the big one for 5 gallons, would slide easily between the inner arch and the vent walls/chimney. I then filled that gap with some of the same high heat insulation blanket torn in pieces and shoved in there from both sides. Then, so I didn't have to look at it forever, I ran a bead of mortar down that gap from the inside

This sounds effective and easy to do so unless anyone can see a serious flaw in it I'll do it that way.

I have a gap on mine which is filled with vermicrete which is somewhat flexible and insulating

Another great idea, thanks David