Just talked to masonary guy about building fireplace/bread oven. Questions and advice needed please.
The wife wants a fireplace and I want a bread/pizza oven which leads me to many questions.
I just talked to local masonary/brick guy about this. He states that he can build a fireplace that looks like one we want, however I question he knows how or what is required of a WFO. Therefore, I need some advice on what I need to describe to him about how the interior construction should be.
First off, here is a picture of the fireplace the wife wants. Questions will be below the picture.
Can a fireplace like in the picture be modified to bake bread or pizza in it with out making it look like an oven in our backyard. (wife is hugh on aesthetics and does not want something that looks like an oven in the backyard.)
What "must" the interior of the fireplace be consturcted of to withstand the heat? Must it be those fire bricks I see alot of in these forums? Do the firebricks need to encompass the entire walls and ceiling of the oven, or just the floor?
Last question..for now: what is the difference between a duel level WFO vs. a single layer. I presume that with a duel layer, the fire is on the bottom layer and the radiating heat is used to heat the top oven area? Is this better than a single layer where you build the fire directly in the oven?
Well although I don't know anything about WFOs, I live in Ipswich MA which predates the U.S. by a century and a half and still has some very old houses. Some of those very old houses still have cooking or baking fireplaces, which seemingly provide some useful ideas. (Such ovens though were used exclusively for baking; the colonials had never heard of "pizza". I have a feeling those ovens don't ever really get hot enough to make pizza properly - some adjustments will probably be necessary.)
The baking ones I've seen are all brick, are massive, and have the fireplace part and the oven part side-by-side. (I also suspect there are some invisible channels inside the masonry to help distribute the heat from the fire to the oven, as just waiting for conduction of heat through the massive masonry could take many hours. They typically had thick hinged metal doors.
As a modification for higher temperatures, one possibility is to consider a "black" oven: in other words put coals in the oven to get it good and hot, then rake the coals out and otherwise clean up the hot black mess as best you can so you can stick in your pizza. If you do this, think hard about constructing the oven for "reasonable" operation: both oven and door large enough to accomodate your broom and handle, some sort of channel or holding area for the hot ashes so they don't fly all over your house, and shallow depressions around the edges you can push stubborn ashes into to at least rake the center of the oven fairly clean.
My guess (but either knowledgeable folks or the mason may advise differently:-) is that fieldstone is sufficiently difficult to build sucn a complex mass with that something else is needed. So what I'd do is build the whole inside with brick, then face it with fieldstone. It will look the same, but folks won't go nuts trying to fit the right kind of fieldstones together to form an oven.
My guess would be that all the bricks used in contruction would have to resist high temperatures, and so pretty much everything would be some grade of firebrick. (It doesn't take anything more to stand up to being an oven wall than it does to stand up to being licked with fire flames.) (Of course I'd not be too surprised if a mason told me that these days "standard practice" was to use firebricks on all surfaces [the firebox, the oven chamber, all the channels] but a lower grade of brick in other places:-)
The knowledge of how to build these things to get the "right temperature" in the oven seems to have been lost. So insist on some sort of "damper" that controls how much of flue gasses from the fire wrap around the oven. By opening and closing such a damper externally, you should be able to somewhat control the temperature in the oven even while a fire is burning.
Something else the colonials didn't have but which I'd suggest is a high temperature thermometer on the oven door (and myabe a second one somewhere nearby). It would be real nice to not have to guess about things like "is the oven hot enough yet?" and "does this damper need to be closed a little when burning this type of wood?".
I'd guess that -despite good motivation and eagerness- the vast majority of masons have never done anything remotely like this. So, in Reagan's words: "trust, but verify". In other words in parallel with your mason do your own thorough research with all the recent books and pamphlets you can find and several websites, and insist your mason draw very detailed plans for you to look over before ordering any materials or otherwise starting to do anything. (Getting all the childrens' books you can find and looking at all the illustrations for "Hansel and Gretel" may be helpful too:-)
that you get a copy of "The Bread Builders" by Scott and Wing and read up on building a wood fired oven before having ongoing discussions with an inexperienced oven builder.
I've seen a lot of wood fired ovens and even the old style mentioned above need to have certain characteristics (such as an oven floor high enough off the ground, an opening with certain porportions to the size of the oven, and on and on) that will lend them an air of "oven" when viewed. (The ones that are mentioned above usually shared the flue and the hearth area with the large cooking fireplace and generally a fire was built in the oven area itself and then raked out prior to baking.)
They can certainly be made to be attractive, but will not look the same as a fireplace. I'm pretty big on esthetics, but I'm a baker and a miller - so I think ovens and my grain mill are beautiful - so the "eye of the beholder" definitely applies.
But seriously, spend the money on the above mentioned book Alan Scott was a famous builder of wood fired ovens (and his children are continuing his business)and the book will tell you all the technical details that you should know before you get too deeply into such a project.
Good Luck!
Based on articles/pictures/etc, combination fireplace-ovens (which also serve as large masonry heaters) are still common in the Scandanavian countries, so you should be able to get some design information and plans. However, I would strongly suggest engaging a local architect with experience in that type of design (and who has an HVAC engineer on call) since you will undoubtedly run into both local code issues and just plain safety concerns. Not to say it can't be done, but I wouldn't recommend trying it on an offhand basis.
Another good source of plans and general building information is:
http://www.traditionaloven.com/
For a few dollars Rado will ship you a CD with several sets of plans, material lists, and hundreds of pictures.
Good luck!
sPh
One such is Tulikivi, a Finnish manufacturer who has a number of dealerships in the U.S. They appear to offer models made of either ceramic or soapstone.
If you google "fireplace oven", without the quotes, you'll probably come with other possibilities, too. Even if you aren't interested in purchasing from one of the sources you find, you'll probably come up with some ideas for your own installation.
Paul
Maine Wood Heat also seems to offer some innovative designs that incorporate both of your wishes. It's worth a look anyway.
http://mainewoodheat.com/
A fireplace is designed to radiate heat into a room (or, in your case, a patio). This means a big, open face, and a flue in the firebox. A WFO is more like a Franklin stove -- it's designed to heat the unit itself with little regard to how cozy the fire looks. A WFO has the additional requirement that the flue be outside the firebox. Further, a fireplace hearth is typically low, near the floor, whereas a WFO is just above waist height. Asking a typical fireplace mason to build a WFO is like asking a car mechanic to build a watch. Sure, they both use gears, but . . . .
If you do design and build a "hybrid", you'll have something that functions well as neither a fireplace nor a WFO.
That said, on a recent visit to Paul Revere's house, I took some time to closely examine the "Colonial style" fireplace/oven. (See below.) The methodology used here, and I assume in other colonial kitchens, was to have a huge fireplace with the oven built into the back wall, inside the essentially walk-in fireplace. (It had a cast iron door, IIRC -- but I may be confusing this one with others I have seen.) The fireplace flue, therefore, could serve both the fireplace and the oven. The fire in the fireplace did not heat the oven. Rather (per the docent), coals or burning wood was taken from the main fire and loaded into the oven to heat it like a conventional WFO. Obviously, this required a fireplace opening much larger than that shown in the picture -- in the neighborhood of six fee wide and maybe five feet tall, with the fire laid off to the side without the oven. This also provided hearth space for traditional hearth cooking, dutch oven cooking and spit cooking. But again, this was not really a combo fireplace/oven. It was an oven built into the chimney beside the fireplace with the two sharing the flue.
ClimbHi
Pittsburgh, PA
> My advice: forget it! (sorta)
Respectfully I will disagre here, on two grounds.
First, as I noted above these types of large-scale masonry fireplaces/heaters/ovens are popular, and being built today, in Scandanavia. So there must be sources of plans, engineering, advice, etc out there somewhere. Admittedly the OP may discover that if he doesn't live in a region with the same (low!) average temperature as much of Scandanavia the concept won't work out (potential to add too much heat to the house during the summer), but it is doable.
Second, even in colonial times it was recognized that the type of fireplace/cooking setup you describe was inefficient even in a land of seemingly inexhaustable wood. Hence Franklin's work on the Franklin stove, and many similar inventions here and in Europe. Since the 1700s our knowledge of thermodynamics, material science, heat transfer, the properties of refractories, and the architect/engineering necessary to tie all that together has advanced tremendously and in my humble opinion as an engineer it should be quite possible to design a usable, efficient combo system. Might not be cheap though!
sPh
Then again, my type of engineering tends to involve slightly larger scale use of energy...
Just some additional thoughts.
Sure the scandanadian stoves serve as room/house heaters and ovens, but they aren't your typical fireplaces. They are more like Franklin stoves made out of soapstone. They are also designed to be pretty much continuously hot. It takes a tremendous amount of fuel to initially heat these things up. Hey, it's just physics -- more mass = more fuel required, and Tulikivis are composed of literally tons of carefully fitted soapstone. Although the Tulikivis say they need a 2-hour burn cycle, that means 2 hours every day.
Tulikivi stoves work on a really cool concept. They circulate the hot flue gasses in a circuitous path down, up and around, through pathways in the soapstone masonry (probably the best material for absorbing and slowly radiating heat), extracting a very high amount of the heat from the combustion gasses. This requires some pretty careful design and fitting and careful consideration of the effects of flue temps on the combustion byproducts. (Without careful design, the gass pathways would quickly soot up and the unit would need to be disassembled to clean.) So while it's certainly do-able, they are primarily furnaces, not fireplaces or ovens.
So, I'm not disagreeing with you -- I'm just saying that if you try to make a combo anything, you almost always sacrifice some of the utility of each of the elements. And I wouldn't expect the average fireplace mason to be able to design and build a properly functioning Tulikivi-type unit. It would be far easier, and more efficient, to build something more along the lines of a unit having a seperate fireplace and an oven, where the oven did not draw its heat from the fireplace.
Admittedly, I've never used a Tulikivi, but I'm guessing that they are nowhere near as versatile as a typical WFO since, for example, you wouldn't have the ability to have a bright fire rolling over the dome while doing a killer pizza. For me, that's one of the principle differences between baking in a WFO and a nice kitchen stove -- you get fire, and even smoke, in the baking chamber when you need/want it. That would be missing from the fireplace/oven combo. I also doubt you could get the combo unit up to the kinds of high temps you can get in a traditional WFO.
An oven heated by an external heat source is known as a "white oven" - as opposed to a "black oven" that's heated by fire directly in the baking chamber. Black ovens are generally better suited to occasional use due to the fact that they are easier to heat and require less fuel, since you're only heating the baking chamber. And while I've never baked in a fireplace/oven combo, it seems to me that controlling the oven temps would be more problematic and determanitive of how you would burn the fireplace fire. Having to douse the fireplace when the oven reached baking temps would seem to defeat the purpose.
So, not impossible, but highly subject to compromise and, IMHO, not worth the headache for a backyard feature. For backyard use, keep 'em seperate and, at most, share a flue. Just my $.02. ;-)
ClimbHi
Pittsburgh, PA
Fast-forward a hundred years or more, past the "walk-in" fireplace. At that time brick fireplaces that included an oven on one side that opened into the room (not into the fireplace area) did exist. It appears those ovens were heated by the fire itself. So such things did exist. The idea of getting plans from other countries that use such things today sounds like a good one.
(At first glance it looks to me like the side-by-side arrangement is used for bread and other baking, but pizza requires a top-and-bottom arrangement instead. But likely I'm just imagining it...)
Also, speaking of Franklin Stoves, a Google Image search for "fireplace oven" turned up a couple metal inserts that include an oven chamber!
(Believe it or not the "walk-in" fireplace was actually an improvement on what came before. The fireplaces at the recreated Plimoth Plantation are truly awful. Their chimney openings at the top were big enough for a calf! With anything other than a huge fire, they caused a net loss of heat because of the draft. The fire that heats the Indian dwelling in another part of the park is much much better. It was hard to not conclude the Pilgrims lack of experience "roughing it" made them effectively idiots in this strange land.)
My husband and I built a WFO about two years ago. I'm not sure how you would make your project dual purpose (fireplace and oven), but I can tell you that the outer bricks can be any kind of brick or stone. In ours, only the actual oven is firebrick. (floor, side walls and ceiling arches and dome.)
The cost to build a WFO depends on a lot of factors - the most important one probably the size. I was told that the materials only for an Alan Scott style oven the size of the one he describes in his book (I think it's 24x36?) would be just under $2,000. BUT, that will also depend on your location and the availability of suppliers for the materials.
If you haven't done so already, read "Bread Builders" by Alan Scott to get a more accurate picture of what's involved. You could then make a list of materials and call around to get a closer estimate.
Stephan
In confronting an oven build the kind of oven you decide to build is reasonably significant. Barrel vault ovens are very heavy, more traditional bread ovens designed primarily for cooking with the fire and ashes removed and the oven sealed. Pizza ovens are lighter and focused more on cooking with a fire in the oven. That said, either can function as the other but there are compromises.
Barrel vault ovens take longer to heat (typically 3-4 hours) while pizza ovens can typically be heated to pizza temps in an hour or so and heat loaded enough for one batch of bread in about 1 1/2 to 2 hours.
Bread Builders is a good book to start with and provides plans for a good barrel vault oven. Forno Bravo is has free plans and lots of great info on building ovens as well as oven kits and complete ovens for sale. An important factor from my experience is that the Bread Builders plans would benefit from more insulation. The FB plans are very heavily insulated.
A key factor to consider is how much bread you want to bake. Conventional pizza ovens are fine for one batch of bread and maybe a second - or even better a slow pot roast or pie or something that benefits from a cooler oven. The barrel vault ovens are typically good for three batches of bread. If you don't plan to make more than 15 pounds of bread at a time, the pizza oven will use less fuel (wood) and IMO be more versatile.
Don't get confused by the hearth design insulation differences between the two! I did and I have a slightly "leaky" hearth. Build one or the other (though you can put more insulation ala FB under a barrel vault hearth.
Good Luck!
Jay