Clay/Outside Bread Oven - Hot water source

[lmnde]

I am planning an outside or summer kitchen for our new place once we are set up, and want to build a clay or brick oven for bread baking and cooking. I'm wondering if it is feasible to lay copper pipe inside the walls of the clay oven for hot water production - has anyone done something like this and what are safety precautions? Does it work for you?

What would be a safe but workable way of a water storage basin, pipes and also an outlet type of faucet - that would not take damage or spring leaks due to excessive heat and contraction/expansion during heating and cooling off? Is this feasible or produce more problems than benefits?

Thank you for your input and suggestions - I'd like to hear yeahs and nays if applicable... Lmnde.

[The Paw]

Off the top of my head, imbedding the copper tubing in the clay might eventually cause it to corrode. I'm not sure about that, but don't know if I would take a chance.

Why wouldn't you just set a boiler with faucet and steam pressure relief valve on top of the stove? That seems pretty simple to me.

A series of copper pipes would work as a radiator and give you more surface area,sto it would heat water quicker I guess, but if you are firing up the stove to bake bread, I would think that would be enough heat that you would not need the extra piping...

[WisJim]

An oven like that usually gets 500+ degrees, and that might be too hot for copper coils, or the water heating coils might cool the oven too quickly. I would suggest putting coils around the flue, or a loop of iron pipe inside the flue, away from the firebox.

[lmnde]

I was not thinking about putting the copper tubing it into the firebox per se but into the masonry around the firebox - and take advantage of the thermal mass to warm the water when it runs through the copper tubes - more like a modern flow through heat element...

When I see myself baking and cooking outside - it would be either several meals to be prepped and baked simultaneously or consecutively as the temps get lower, or hand in hand with butchering and prepping meat for freezing, or working through garden produce [drying etc] - and it would be nice to have warm/hot water for clean up and prep that you don't have to drag in by the bucket.


Back to the practical application - I am more concerned about the copper tubes getting damaged by the high baking temps or the thermal mass cracking due to quick lowering of temps when you have water flowing through [if it makes much of a difference at all]. I am also not sure what would be the correct way to set up a flow through system - incorporating some type of holding basin [what material to use for easy cleaning and no corroding and ruining the water purity] or just a simply water hose type of hookup for straight flow through?

Thanks for helping me thinking this through... Lmnde

[WisJim]

Originally Posted by lmnde

Back to the practical application - I am more concerned about the copper tubes getting damaged by the high baking temps or the thermal mass cracking due to quick lowering of temps when you have water flowing through [if it makes much of a difference at all]. I am also not sure what would be the correct way to set up a flow through system - incorporating some type of holding basin [what material to use for easy cleaning and no corroding and ruining the water purity] or just a simply water hose type of hookup for straight flow through?

There should be water in the tubing before the oven starts heating and after it has cooled. Should be a thermosiphon arrangement with some kind of storage tank, and then the temp extremes in the piping won't happen. If you run water into dry hot pipes you may have an explosion of steam--not good.

[peacebaker]

I have a mud oven, new this year so not a TON of experience. So far when I've had a fire going, it takes a LONG time to get the thermal mass of the oven hot. I keep the fire going for a good three hours, and the exterior of the oven (9 inches of clay/sand/straw) is just getting warm to the touch at this point. It's very hot at the mouth of the oven, and inside obviously +500 degrees). Once you get that heat through the entire mass of the oven walls, it probably peaks about the time you are baking, and does hold it for a long time (hours). The exterior is hot, but touchable (not for long periods, but lets say it's not hot enough to burn you if you brush up against it.

I'm sure inside the walls it's a little hotter than the exterior, but I'm not sure it would be worth it for water heating? I think it might be more efficient to just use the actual fire (or leftover coals after you sweep them out) to heat up a kettle of water. Or perhaps if you had a design with a chimney you could create a water heater around that.

I know what you're getting at though, it does make sense to "harvest" all the energy that's going into the process. I'm always looking for things to bake/dry after my main batch of breads/baking is done.

[lmnde]

Thanks peacebaker. Do you use yours a lot? Is here anyone else who has one and uses it regularly? What else other than bread, pizza and potatoes do you bake/cook in it? Do you use it for roasts or stew or something along this line as well? Can you bake cakes and pies as well or do they taste "smoked" ?

Does anyone have one combined with a BBQ grill? I saw one model where you actually pushed the coals out through an opening in the back of the bake chamber [after the bake chamber is heated] into an open bbq section with a grill on top for grilling.

[Cyngbaeld]

I've heard of putting a pot of beans in to cook when done with the bread. I'd love to have one of these, but first I need to stop moving every yr or two! LOL

Why can't you build something like a platform over the exhaust vent of the oven that you could set a large kettle on? You could fill it with a hose. Maybe get one that has a tap near the bottom so you wouldn't have to lift the whole thing up or down each time?

[peacebaker]

I'm still new to baking with it, but we've used it 3-4 times now. Each time gets a little easier. The cooler fall weather made it easier too, as the breads rose more slowly and I didn't feel as rushed to have the fire ready.

I've baked multiple batches of bread, pizza, scones, an apple pie, and roasted beets/potatoes. It's great for granola too once it's cooled down to 300ish degrees. I don't notice a smokey taste to things.

This last bake I had a new oven thermometer and kept track of temperatures better. After cleaning out the coals and closing it up to "soak the heat in" for about 30 minutes, we buried the needle on the thermometer, which goes up to 600 degrees. We baked pizzas in 3-4 minutes, and the next batch of breads (small ciabatta loaves) baked in under 10 minutes. Regular loaves followed, and baked in about 20-25 minutes, so I think it was 450-500 degrees.

After this I put the thermometer back in. We closed it up after the breads, and about 4 hours later it was still 400 degrees inside. I baked a batch of scones, and after opening the door a few times it dropped to 350 degrees. Granola was next, and that was done in 30 minutes.

Now that I'm getting a better picture of the temperatures and how long they last, I'll be ready next time to try things like a roast chicken or casserole etc. Here's a rough outline of time , temps:

1:00 pm - started fire
5:00 - let fire burn down to coals
6:00 - scooped out coals
6:30 - 600+ degrees
10:00 - 400 degrees
11:00 - 325-350 degrees
7:00 am (the next day) 200 degrees

I think you could bake/roast just about anything in it, as long as you keep an eye on the temperature. Also if you wanted to re-fire it the following day, I think it wouldn't take very long to get it up to temperature. If I was really organized, I could probably cook for a week in one firing!

[lmnde]

Thanks for sharing! How big is yours roughly in measurements? Do you by chance have a photo and with what materials did you build yours? And lastly - what type of wood did you take to burn? Do you think using a different type of wood that burns faster/hotter may cut down the heating up time? I've heard of most ovens takign about 2-4 hrs average burn time to warm up...

[peacebaker]

There were a couple of threads in the cooking/craft forum while I was building it this summer, with lots of pics:

Building the mud oven

first bakes in the oven

I used Kiko Denzer's book, and we pretty much made the basic oven the book describes. It's made of cobb (clay, sand, and straw). The interior floor is about 27 inches in diameter. The walls are 9 inches thick which makes it close to 4 feet across on the outside.

Here's a picture from this weekends' baking. We recently added a roof to protect from the elements a bit better:



It's been a fun project, and fun to share with the forum too!

[lmnde]

Oh my - it is beautiful! I will look over the links - thanks a lot for sharing!

[vicker]

You don't want to use copper pipe as the heat source fot the type of water heater you are talking about. Do more research.