Insulating front of oven landing

[Karangi Dude]

Hi Bevan,
You are right the entrance (landing / counter) will get hot from the radiant heat unless it is a very deap landing. Mine is shallow and does get hot but not hot enough to burn me it is not a safty issue, I use it to keep things warm it is quite handy.

[Lburou]

I put an eighth inch air space between the inner arch and the entry arch. You can see the daylight though the flu and the heat brake in this picture...


I cut rigid insulation and placed it on the outside radius of the air space, then covered it with vermicrete to seal and insulate. Haven't been over 600 F yet, but there is a large temperature difference between the inner arch and entry arch. For me, it was all to preserve heat for baking.

ADDED later: After the sixth day of curing fires my oven dome temp was 830 F, (433 C ), for an hour with a floor temp of 650 F, (343 C ). The top brick of the inner arch was 512 F, (266 C ), and the inner arch of the entry was 392 F, (200 C ). These numbers show the temperature difference between the inner arch and entry arch of 150 F, (66 C). Well worth the extra effort. In a do-over here, I might increase the air space to a quarter or half inch.

I made another air space in the oven floor about 4 inches outside my inner arch.
The air space will be between the firebricks and granite portion of the landing.
Also used a one inch filler between the oven floor and base for the granite.

The yard stick is where the granite goes.

This one shows the granite in place, but no entry yet. Designed after Karangi Dude's entry, I made mine a bit wider and a bit shallower than most. You can see the pencil line where I made the entry...

Added later: The temperature difference between the oven floor and granite was about 50 F, (10 C ), but I haven't filled that space with ashes yet, it may improve slightly. In any case it will aid the granite in a long and healthy life

Not shown is placement of two triangular insulated fire bricks that are now under bases of the entry, providing another degree of insulation.

I don't say everyone should do this, but it felt good to me :smiles:

[BriggsARNP]

This will give me a lot to think about. I am using my graph paper to plan out how I want to do things. This will give me a lot of help. Thanks

[david s]

Lee,
I don't think you'll be sorry you went to the trouble of doing what you've done. You will find that even after a few hours of firing that you can still hold your hand against the outer arch.You Will also appreciate the shallow entry every time you put anything in or out if the oven.

[Lburou]

Originally Posted by david s

Lee,
I don't think you'll be sorry you went to the trouble of doing what you've done. You will find that even after a few hours of firing that you can still hold your hand against the outer arch.You Will also appreciate the shallow entry every time you put anything in or out if the oven.

Thanks for the encouragement David, I felt like I was in uncharted territory as I devised those measures....I did read all the heat brake threads I could find and gleaned from each published account. Actual implementation was not difficult at all, the biggest obstacle was to decide which materials to use and where -dictated by what I had on hand.

BTW, I also added some insulating firebrick between the top of the entry and the flu, and between the entry, the flu, and the block enclosure -got the idea from Brickie in Oz's latest build. I wanted to confine the heat and slow heat gain into the block enclosure.

Not very pretty I know, but I will be facing the entry and flu with granite, and the stand and enclosure with the white rock you see to the right of the entry, accented with brick from the house......Eventually.

Added later: During the fire reported above in post # 12, with the dome temp at 830 F, (433 C ), the clay flu approached 300 F, (148 C ). At this time the insulating fire brick at the base of the clay flu and between the flu and the block enclosure hovered around 160 F, (71 C ). This will ensure the desired effect of containing heat in the flu and slowing heat migration into the enclosure

P.S. The flu heats up well enough, despite the insulating bricks at its base, that was a concern -the second length of clay flu makes a LOT of difference in the draw and is necessary in our case.

[GianniFocaccia]

Not very pretty I know

It is to me! Lee, your efforts to incorporate leading-edge elements into your oven shows forethought and a willingness to push the design evolution of the WFO. This is obviously a difficult process with mass-produced ovens.

I'm curious to learn how the double heat-break affects the outer arch and granite landing temps on a shallower-depth entryway and what kinds of heat-retention numbers you get. Keep the pics coming!

John

[Lburou]

Originally Posted by BriggsARNP

This will give me a lot to think about. I am using my graph paper to plan out how I want to do things. This will give me a lot of help. Thanks

We've seen some pretty sophisticated drawings using google sketchup....Its free. If you are so inclined it might work for your drawings.

Also wanted to show Wade Lively's heat brake drawing for the landing that gave me a place to start.

[BriggsARNP]

Thanks Lee. I will have to have a look. My drawing skills are poor at best. I have to submit plans to the local building dept and it would be nice if they made sense.