Mk2 Questions about Barrel build

[awalker]

Hi All

I currently have a clay/cob wood fired oven in the garden. Built it three years ago, with a lot of help.
Its being going really well although, there are a lot of things wrong with it. As it was not as fully researched as I thought.

Down sides are its not water proof and its at the wrong end of the garden. Especially in winter, drudging down there in the mud. So it limits the use a little, which I am hoping to change. The current wood fired oven is mainly used for pizza, bread, roasts and slow overnight cooking.

To make life easy and because I have some time constraints I was looking to use the barrel oven kit from kilnlinnings.

I have a few questions about it.

1. Will it have sufficient thermal mass if insulated from the base and vermiculate over the top, for long slow cooking? If not what is best way to add mass?

2. Not sure of the chimney being in the main body, I thought they are normally in the door way section for a reason i.e. not loosing heat

3. Its not cheap so think it would be cheaper to buy the arches and separate bits from kilnlinnings.

Any help would be appreciated

[moonhead]

Hi,
I looked at the Kiln Linings barrel kit too when deciding on my build. Like you I wasn't sure how a chimney in the main body of the oven would work so opted for the individual arch kits 4@ 710mm to form the chamber. Then used firebrick to create the entrance & chimney.
There is plenty of thermal mass for slow cooking, I have 50mm of blanket and 75mm vermicrete over the oven and 50mm cal sil board under.
As for cost I think it work out pretty similar for me taking into account the additional firebricks for the entrance / chimney and the back of the oven. Below is a link to my build, hope this helps.

ukwoodfiredovenforum.proboards.com/index.cgi?board=7&action=display&thread=1112

You can check out other builds in the Barrel / Vault oven section on the forum too.

Good luck
Rick

[awalker]

Thanks for the reply moonhead.
A very nice build you have there, have followed it but did not click its the kilnlinnings arches!

Think that sounds like a good plan for the chimmney. Need to sort out the order and get on with it in the new year.

[purrcat]

I have built a modular Kiln linings oven and you can view it here:

ukwoodfiredovenforum.proboards.com/thread/2293/modular-oven-surrey

Having finished the oven at a bad time its quite difficult to dry it out - but progress is being made.

My feeling about the Kiln linings product is that it is quite well thought out and not bad value for money. In my case, much as I had time to build the plinth, the thought of shaping all of the individual dome bricks and cementing them together was simply too much. Consequently, I bought the kit and did it that way. The refractory stone work is pretty massive and, once dried out, should hold a huge amount of thermal mass for ages. IMHO it really is worth also properly insulating the oven. The thermal blanket, plus the chicken wire and aluminium foil and then a liberal coating of the Kiln linings version of vermicrete and then (my addition) a double coating of K-rend do a pretty good job of keeping the heat in. I get a certain amount of warming about an inch or so around the flue and a little bit where the arch touches the dome. These are the places where heat can find a way through because they are interfaces. I also decided to isolate the arch from lining by adding a fire rope insulator. Plus, obviously, the hearth bricks are isolated from the base with Calsil. The concrete base has a huge potential to loose thermal mass and the Calsil seems to do a pretty decent job.

With regard to the chimney. I share your concern. I honestly don't know the answer to that one. I agree that most of the heat will be retained by the lining and by providing some thermal isolation between the flue and the dome (using fire cement) it isolates the flue from the K-rend and stops heat leaking. It also does a very important job in that it absorbs expansion from the flue which could otherwise crack the render.

Ask me in a year or so if the method really does retain heat.I'm keeping my fingers crossed that it will.