Plugging the chimney for retained-heat cooking

[Fio]

I've been experimenting with retained heat cooking in the oven, and I've noticed the temp drops off pretty fast (I have a dome-style pompeii oven). It seems to me that, in addition to sealing off the door, I could save a lot of heat by blocking off the top of the flue liner used as my chimney. Yet I don't hear of anyone doing that, even among Alan Scott/bread oven users.

Is this done? Any drawbacks (other than trapped smoke, which is a definite plus when cooking meats)?

Thanks.

- Fio

[DrakeRemoray]

When I finally make my door I plan to have it fit the inner opening of the oven, past the vent/flue...When I stacked up bricks as a door, I put them inside the oven opening all the way up so that they hit the bottom lip of the vent.
Drake

[james]

I think Drake has it right. The door should fit snugly across the opening into the oven chamber itself -- not the arch that forms the opening into the oven landing. That way you can cut off the air supply to put out your fire, and completely hold in your heat. That should help. Leaving your door off the oven for retained heat cooking is like leaving your oven open -- we'll it's not that bad, but you get the idea.

I cooked once in an oven where the door closed at the front of the vent area, and when I tried to put the fire out, it kept breathing by drawing air down the chimney. Not a good design.

James

[Fio]

Originally Posted by james

I think Drake has it right. The door should fit snugly across the opening into the oven chamber itself -- not the arch that forms the opening into the oven landing. That way you can cut off the air supply to put out your fire, and completely hold in your heat. That should help. Leaving your door off the oven for retained heat cooking is like leaving your oven open -- we'll it's not that bad, but you get the idea.

I cooked once in an oven where the door closed at the front of the vent area, and when I tried to put the fire out, it kept breathing by drawing air down the chimney. Not a good design.

James

A-HA! I've got to completely re-think my door design. My door currently goes on the outside. I'm going to check to see what can be done to block it off BEFORE the chimney.

I cannot believe I never thought of that. Amazing!

[maver]

you could still plug the chimney, no need to make a new door.

Probably easier to make a new door (or modify) than install a damper after the chimney is complete. I think I've read here that some oven builders have used a damper, but considering the insulation efforts are focused around the dome in the conventional design I wonder how well heat would be retained with a damper and outer door.

[CanuckJim]

Fio,

If you plan to bake bread, you definitely need a door that seals the oven opening. This is both to retain heat and so the steam you add (garden sprayer, etc.) will stay in the chamber and caramelize the crust. Your breads won't be properly baked without it.

Cheers,
Jim

[james]

Excellent point Jim. Thanks for that -- no one had mentioned that yet.

Would you making a quick posting on how you do steam in your oven? I will make it a sticky to keep at the the top of the Bread section.
James

[Alf]

At the Museumsdorf museum in Cloppenburg, Germany they have several preserved and rebuilt wood-fired ovens. Apparently in the old days they baked the hard German black bread over several hours in a cool oven and steam was an essential part of the baking process. To obtain a good airtight seal round the wood doors and seal up the cracks in the wood of the door they used cow dung. I am assured this true and the bread was wonderful.

Alf

[arevalo53anos]

Nowadays, in constructing clay ovens, the cow/horse dung is used mixed with clay and grass or sedge.

The grass helps the structure to do not have crashes, the dung and clay (pretty well mixed) makes the dome hard and impermeable.

When dry the oven is a strong construction, heating too well and with no smell more than the smoke and bread aroma.



Luis

[CanuckJim]

James,

I have used two methods for generating steam in my oven. When the ash has been raked out, I leave my high mass oven to moderate for two hours, about the time I take my slow rise doughs out of the fridge. Then I brush and mop the hearth. At this point, I either put an old sheet pan loaded with damp rags into the oven, or give it a long spray with a cheapo garden sprayer. When the breads go in, there should be visible steam in the chamber. Once they're loaded, I give the oven another long spray, pointing the nozzle upwards, not at the breads. Again, there should be visible steam in the chamber. Once more, too, without steam, the crust will not develop properly and caramelization will be underdeveloped.

To retain the steam, it's important that the door seals the oven opening. Although I made my door quite carefully to ensure this, I still have to prop a brick against it to retain the steam, mostly because the metal part of the door has warped a bit from heat.

Simple, but effective.

Jim