WFO Help?
Well, I poured my slab! But didn't put in the insulation! I have emailed the yahoo group for help too, but thought I might as well post it here and see what other help I can get! :) I'm going for the Alan Smith vault style oven. With all I'm reading, I should have put in the insulation before hand! Ah...my help was here and I didn't get the book in time (the bread builders), and now "what's done is done". But, can it be fixed? With my rocks and cement and a fire brick on top I'm at 37 inches high. Can I put some kind of insulation in the shape of my hearth floor, cover it with cement, and put the fire bricks on top of that? I probably shouldn't go above 40 inches high.
Any help would be appreciated. Thanks! I know it's messed up, don't yell at me too much! :)
Faith
I have been trying to post a link but for some reason a spam filter triggers. Try
pizzamaking, you put in the rest. It's a com. There is a hearth oven thread.
Faith,
Contact me via the Forum or email me a info@maygbread.com. There is a good, workable solution. DON'T PANIC: Hitchhikers Guide to the Galaxy.
CJ
Jim, I just wrote you this whole long email and sent pictures, but it came back to me. I will try and send it again!! YES!!! Will you PLEASE help me!! I have been reading a million threads today all over the place and you are in all of them!! I would so appreciate your help!! I'll try and send my email one more time!
Thanks a ton!
Faith
CJ, is your email info@maygbread.com? It keeps coming back to me. I'll wait to get your email, then send it again. Or you can email me at handsbestrong@gmail.com
Thanks!
Faith
Is it maybe marygbread.com. Chesk it out.
Thanks for your help Marty! Tried it and I think it worked! :)
Faith
Insulation under the slab will do two things: 1) it'll help the slab heat a bit faster, since less heat is lost to the area under the slab during heating, and 2) it'll help the slab stay at temp longer, since almost all heat transfer from the slab is into the oven instead of out to the surroundings.
In your case, unlike many ovens, you have masonry fill under the slab instead of air. That will act as an additional heat store. So your slab will heat a bit slower, but will also be slower to cool, since the whole base will act as a "slab" and release heat back into the oven.
So, as they say "fuggetaboutit!"
But read, and follow, the book carefully for the next steps. Properly constructing the door, dome and surrounding cladding is more important than the slab.
ClimbHi
Pittsburgh, PA
Hey ClimbHi!
I finally found a link to all the pictures of your WFO build! Wow! It's awesome!! You guys did a great job! I was showing my mom all the food you guys cooked in it! She loved it! I am working on fixing this problem. I'm so thankful to all you smart ones who have walked before us, and can help all those who are following behind!! :)
This oven building is nice, but I wish someone else could just build it for me so I could START COOKING!!! I just want to get it over with so I can put my bread in it!! But hey, no use doing it all wrong and getting bad results later!! That would break my heart!
Just pressing through! One day at a time! Thanks for all your insight! I have read your comments on many different threads and appreciate your time!! :)
Blessings!
Faith
Even with no insulation under my slab, and exposed to the air, I found the underside of the slab never lost enough heat to worry about. Never more than ten or fifteen degrees above ambient air. Sure, you could worry about ten degrees, if you want. But with your solid slab, no worries.
Fifteen degrees over 20 or 30 sq ft is huge if you want to hold heat overnight or if you never let your oven cool and want/need to conserve fuel, like in a commercial setting. But obviously no big deal for occasional fire-in cooking, like pizza, or short bakes, like a load or two of bread.
But sub-slab insulation is so cheap and easy, no point in intentionally skipping it really. Kinda like houses -- they used to build 'em with no insulation at all when heat was cheap. These days, you'd quickly go broke from heating bills if your exterior surfaces were 15° warmer than ambient. Heck, radiant floor heat is only about 15° warmer than room temp, and that'll keep the whole house toasty and warm.
It really depends on what you plan to use your oven for. For example, we frequently roast a pork butt overnight, with a starting temp of 300° -- and we don't want to lose more than 50° over the next 12-14 hrs. Good insulation all around the box makes that possible. It also makes re-firing on subsequent days almost trivial, being able to reach baking temps with just a fraction of the wood it takes to initially heat the oven.
So, the bottom line is that for some types of cooking, you don't really nead any insulation at all. But for others, you need a lot. Not a one-size-fits-all kind of situation.
ClimbHi
Pittsburgh, PA
If you go to the forno bravo site/store, they sell a 2" ceramic insulation board for under your floor. You would place that on your newly poured concrete and then lay your oven floor on the insulation board. The floor will be your heat sink and the insulation will keep your heat from tranferring to the cement. I don't think you did anything wrong to this point.
A few years ago I built a 43 inch dome based on the Forno Bravo plans, and I'm delighted with the results. Understand that this design is not primarily a Bread oven, although I have done one load with 8Kg of dough and the results were really good. This style oven is a multipurpose WFO. All of this is just background to my feeling that insulation is a must. Whatever your goal is, heating the support structure of the oven is not likely one of them and insulation really keeps the heat where you want it, in the oven. As for hearth height, you have a range that will work for you, not a specific height. If you find that you need to adjust the hearth height by the amount of the insulation, add tile or bricks to stand on, not hard and not expensive. I placed 2 inches of rigid insulation under the floor and bricks directly on this insulation, it works spectacularly well. Rigid insulation is available from many sources, Forno Bravo is one, a foundry supply company or ship building supply or industrial insulation supply company will also have what you want. I paid $200 for a 2" by 48" by 72" board. These boards come in 4 by 8 foot sheets and if you can minimize the joints then laying your bricks directly on the board is easy, no mortar necessary..
Chris