stuck before even starting

[PollyG]

Hello, I am new to this forum - I'm trying to figure out what oven to build for home use, and the more I look around, the more confused I get. I'm mainly interested in bread baking, and would like an oven that retains enough heat that I can do 2 or more bakes in a row using retained heat.
I started out thinking I'd just follow the instructions in Alan Scott's book, then heard about the FB Pompeii kits, the new Casa100 kits, and the Mugnaini Medio100 kits. I would love to hear what people who do home-scale WFO cooking have, and especially would like feedback from anyone who has built and/or used more than one of these.
What I'm wondering in particular is why the Mugnaini kits are so much more expensive than the FB ones, and if there is anything noticeably different between them in terms of performance for the kind of cooking I want to do.

Thank you all, and this looks like a super useful forum,
Polly

[brickie in oz]

Re: stuck before even starting

My current oven is a barrel with the best elements from all types, Alan Scott, Alan Watt, Pompeii, plus my experience from years of chimney and fireplace building incorporated.

Have a look here. Wood Fired Pizza Oven Number 2 : BrikiWiki the home of online brickwork.

Im currently in the process of writing it all up for an ebook for Amazon, it may be a while before its ready.

PS, a while for me is weeks.

[PollyG]

Re: stuck before even starting

Thanks for your input, Mick. I think the reason nobody else responded to this thread is that I reposted it later, thinking that this original one had gotten lost in the ether. Turned out it didn't, but I never did figure out how to delete this original one.
Anyway, I got lots of useful responses to the second thread, including from Al/Brickie (and I'm excited about your ebook, Al!), but Mick, you are the first person who has suggested using common red brick. I thought that using those wasn't recommended, because of the heat stress caused by rapid heating and cooling. Is this not true? Also, are there differences between firebrick and common red building brick in terms of heat absorbtion and radiation abilities? I frequently run across unwanted piles of red brick to be had for free or at least very cheap; it would be really cool to be able to put them to good use.

[OscarA]

Re: stuck before even starting

Over here in Oz a lot of build are done using solid red bricks due to the high costs of fire bricks ($3-5 each). I don't think that is the case in the US or Canada so most builds are done with the fire bricks.
If you do go the red brick route be aware that not all red bricks are the same and unless they have been fired in a high kiln oven they could fail.
Some people say use a large hammer and hit the brick as hard as you can in the middle, if it breaks cleanly it's fine if it shatters it's not.
I personally used fire bricks to play it safe and figured the oven will last for years and the money spent on it will be long forgotten.
Good luck with your build.

[Mark Watkins]

Re: stuck before even starting

I built a Primio2G100. I wasn't looking for a long project just a good functioning oven in a reasonable length of time. I couldn't be more pleased with the results. We typically fire the oven on Friday afternoon. It takes two hours to reach cooking temperature. Pizza takes 60 to 90 seconds. The next day at noon the temp is still about 600F. We will let it cool a bit and bake a couple of loads of bread. We then will put in a roast for the evening. The next day it will still be 400F, works great for a pie and maybe some ribs for the evening.
The oven floor sits on five inches of the ceramic insulation and the oven dome is covered with four inches of the ceramic blanket insulation. We then built the outer "dog house style" and filled the cavity with vermiculite until we had the dome covered by four inches. We followed the FB curing schedule and have had no cracks or problems. The FB folks were easy to work with and this thing is a joy to use. My wife thought it was just another weird project but now she loves coking all weekend on it and not heating up the kitchen. These things work!

[azpizzanut]

Re: stuck before even starting

Hi PollyG,

Gosh, you live between LA and SF, right in the heart of WFOland. Lots of dealers, manufacturers, and importers within a few hours drive. You can visit them and ask questions.

The others gave you good general advice about ovens but you still have a lot of work to do getting the foundation slab, block base, and hearth slab built then more to enclose or cover it. You can opt to have a metal frame built to put the oven on too. An oven kit may have a lot going for it but easy and quick they are not. Some are very heavy as well which can make delivery and siting a challenge.

A Pompeii oven of 42" will cook anything but does take a little longer since it is made with half fire bricks and you'll need some equipment and tools. Those are the facts. Another fact is that building your own oven is very satisfying and there is a lot of help here on the forum if you have questions no matter which oven style you choose.

Cheers,

[texassourdough]

Re: stuck before even starting

Hi Polly!

Sorry I was slow getting onto your message. I will offer a couple of observations from the perspective of a serious bread baker. Suggesting you want to be able to bake multiiple batches of bread raises interesting issues and possible questions.

I originally planned to build a barrel vault oven from Ovenmaster plans but eventually decided to build a 1 meter oven from FB and added an extra inch of refractory cement to increase the mass. I find that I need to have at least 12 to 15 pounds of dough in the oven to get enough humidity to get the crust quality I want - even with spraying. So...two batches in a one meter oven should be in the range of 30 pounds of bread. Is this what you intend?

Oven mass and insulation are an interesting tradeoff. For pizza only there is no issue other than heat loading time (i.e. firing to temp), for single batch baking a pizza oven is fine and has the advantage of heat saturating in a shorter period. For mutliple batches a conventional pizza oven is likely to be a bit light and not have enough heat for the second batch.

Heat available for cooking is basically a function of mass, heat capacity (storage of heat, BTU per lb degree), and temperature of the material. Baking 15 pounds of dough requires about 2500 Btu to bake the bread - not including losses opening and closing the oven, spraying in the oven etc. That is enough to drop the temperature of 400 pounds of refractory (heat capacity appx. .2 Btu/lb*degF) by about 30 degrees F.

Martin has a super insulated oven that retains heat well and will easily bake a couple of loaves from a heat retention perspective but it may of may not do a full load well and it is very likely to be marginal at being able to bake a second batch (full load) of artisanal lean breads for the starting temp will drop significantly. (By the way, Martin, I would love to see your oven and explore its heat characteristics! Your insulation is awesome!)

The challenge is heat loading time. A pizza oven can be ready to do pizza in about 45 minutes and heat loaded adequately to do one big batch of bread in about 1 1/2 to 2 hours (and yes a nominal one hour heat soak is necessary to let the heat equalize!) On my oven I need about 2 1/2 hours to get enough heat into the refractory to gracefully bake two batches. A barrel vault typically needs more like an hour and a half to do pizza and 3 or more hours of heating and an hour or more of soaking to be ready to bake.

Barrel vaults are wonderful if you use them every day for they don't cool down a lot. I should also note that the Scott designs are not particularly well insulated so don't hold heat like Martins if that is important to you. You can somewhat overcome that by insulating but there are other issues with the Scott design (like a leaky hearth that can't be gracefully insulated) that suggest to me a modified Scott might be superior.

I would encourage you to strive to find a local oven or more and try baking in ovens before you build one. SFBI has a wood fired oven baking class that might be a good investment!

Good luck!
Jay