Date: Sun, 27 Jan 2013
Subject: Humble Bread oven
To: Norbert Senf <mheat(at)heatkit.com>
Here are some pictures of a 6x10ft bread oven we built September 2011 in the Prince Edward County. I will put a complete article on my web site at some point, but here is some info to share.
My design decisions were inspired by low-vault ovens built by John Fisher in Sweden http://www.fishermureri.se and also influenced in part by what I have seen on pictures of French traditional guilard-style ovens Antoine Guerlain brought from his trip to France with Dave Bauer http://farmandsparrow.com/ . One of the main features isÂ that the oven was designed for use of canvas bread loaders (a device enabling baker to load and unload several rows of bread at once in matter of seconds with very little effort – something that every production bread oven I design and build will be equipped with from now on). The doors system for the oven was designed and built for this purpose byÂ William Davenport of Turtlerock Masonry Heat http://www.turtlerockheat.com/.
The oven is direct-fired and features:
-Â Â Â Â Â Â Â Â Â a very low low-rise vault of 12″ maximum height and no reduction into a single exit, but instead two main exits: one in each back corner right in the vault (natural reduction of about 2″ due to vault rise).
-Â Â Â Â Â Â Â Â Â a firing door at the back of the oven. We have decided that keeping all wood dirt out of the bakery is a good idea and bakery plan allowed it. I made another exit above the firing door simply to have firing door as high as possible while avoiding spillage when loading wood.
This central exit has a dropped in stainless pipe (a-la bagel oven chimney exit) to be flush with top of the firing door just to avoid venting the hottest gases out when firing. This way there is no spillage, but the hottest gases do not escape. Each of three exits has a dedicated sliding damper just above, right on top of the vault. The exits, therefore, are only shallow niches in the vault, so no large space of an open smoke chamber above. All exits come into a single smoke chamber that can potentially have additional chimney damper at the base of the chimney to avoid circulation in the chimney, but it was not installed in this case. With two main exits, plus central exit, with separate dampers, there is ability to control draft and firing and have some control over direction of the gas flow inside.
-Â Â Â Â Â Â Â Â Â a triple layer jack arch with a reinforced bond beam over the 6ft-wide loading door opening. I think the strongest solution possible…
-Â Â Â Â Â Â Â Â Â a continuous expansion joint John Fisherâ€™s style with staggered side joints in walls and in the vault at the middle, plus expansion joint in the upper brick layer in the vault at the ends of the vault.
-Â Â Â Â Â Â Â Â Â Thickness of oven walls and vault is 9â€,Â hearth is 10″.
-Â Â Â Â Â Â Â Â Â The oven sits on total of 6″ of insulation boards – super-insulated.
-Â Â Â Â Â Â Â Â Â Very strong I-beam harness with side supports.
-Â Â Â Â Â Â Â Â Â The oven is insulated with ceramic wool/mineral wool/aluminum foil in multiple layers to the total of 11â€.
-Â Â Â Â Â Â Â Â Â Brick facing on front, cement board over metal studs everywhere else.
-Â Â Â Â Â Â Â Â Â Shallow and deep mass thermocouples in the hearth and the vault connected to a reader.
The last attached picture is with the owners: Henry Willis (baker) and his wife NatalieÂ Normand. Our masons who worked with me on construction of this oven, Sergei Kouznetsov (right) and Matthew Froud (left) are also on this picture.
Henry’s feedback on the oven performance has been very good. The oven keeps heat for a very long time and with proper planning can bake over 800 loaves from one firing. Henry has found that our goal to avoid necessity for steaming with the oven design was achieved – he gets great results without introducing additional steam – all moisture comes from the dough.
Henry is very comfortable baking with high percentage rye and his bread, and any kind I have tried is very good. All organic flour, natural levain, no commercial yeast. Pictures of several varieties of his bread are attached.
Orangeville, ON Canada