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trenchn 01-17-2008 01:45 PM

WFO Progressing Nicely, but Help Needed.
Hi Everyone,
My oven is coming on a treat, a brief history.
Brick and timber supported platform. 50mm paving slabs covering a 1.8m x 1.8m base.
900mm internal diameter oven. Fire bircks cut into a 900mm diameter circle.
Half bricks used to form walls and dome. Doorway sorted.
Pictures will follow if anyone is interested.
A glimmer of hope for "Oveneers" on a tight budget.
My WFO is built entirely from reclaimed materials. My first expense will be a bag of cement that is being delivered tomorrow. Approx 4.00 Sterling. The bricks were gathered from various people that had some left over from projects. The fire bricks came from old night storage heaters. Paving slabs from someone in the village that had just had a new patio laid. Timber, reclaimed fence posts saved from when my fence blew down. Sand and first bag of cement saved from when I built a small extension. So far total cost 4.00.
Now my question. I have built the inner skin of the oven and now want to put an outer skin around it to insulate and improve the looks. I have space to put some insulation between the two brick skins. Is it worth it or is approx 8 inches of brick good enough insulation?
If it is worth it what should I use for best effect?
thanks for your help.

arevalo53anos 01-17-2008 02:03 PM

Re: WFO Progressing Nicely, but Help Needed.
Bricks = heat mass.
More bricks, more energy to sink, more fire. More fire, more wood, more time to get the oven hot.
No isolation over and under the oven, heat running out top and down. Less time to bake without fire in oven.

You do need an isolation between bricks and under the oven hearth!!!


jeff 01-17-2008 03:58 PM

Re: WFO Progressing Nicely, but Help Needed.
Good to see you giving new life to materials.
Give serious thought to splashing out on 25mm ceramic blanket. A 7600x610 roll cost A$200 delivered here, but you should be able to do much better in a civilised land. Get a couple of bags of vermiculite to fill any spaces.
You won't regret it, and you can't add it later.
Cheers eh,
Luddite Jeff.

dmun 01-18-2008 05:24 AM

Re: WFO Progressing Nicely, but Help Needed.
An airspace between the two brick layers is just not enough insulation. Skimping on a couple bags of agricultural vermiculite or perlite will mean that you will be burning at least twice as much wood as you need, and in the UK, firewood isn't cheap.

And yes, we want to see picutres!

trenchn 01-18-2008 10:22 AM

Re: WFO Progressing Nicely, but Help Needed.
Thanks to all that replied.
I will purchase vermicelli, or whatever it's called, and investigate insulation blanket. I was considering the insulation used in lofts. It's fire retardent and obviously insulates well. Any thoughts?
Pictures will follow when it stops raining long enough to take some photos.

dmun 01-18-2008 01:43 PM

Re: WFO Progressing Nicely, but Help Needed.
I once used blow in insulation in an old house, it was celulose fiber that was treated for fire resistance. I hope this isn't what you are talking about because you need something that will withstand repeated exposure to high heat, like vermiculite, perlite, or volcanic pumice. Weren't all those night storage heaters you took apart insulated with something like that?

trenchn 01-19-2008 08:49 AM

Re: WFO Progressing Nicely, but Help Needed.
Photo's now uploaded in "Dome and Floor" section.
Insulation wise I am thinking a rigid polyeurothane for under the floor. Celotex or similar. This is heat and fire proof and has extremely good insulation properties.
For the upright part of the wall a similar product or vermiculite and for the dome vermiculite as thick as I can. Does anyone know how I work out how much Vermiculite I need. I can get 100ltrs for about 18.00. Does that sound about right?

Frances 01-19-2008 09:21 AM

Re: WFO Progressing Nicely, but Help Needed.
Hi Nick,

Lovely pics, thank you for posting. Its always nice to see a new dome, and I really like the look of those red bricks. Very cool!

...I'll let someone with more experience give advice on the insulation questions. :)

Acoma 01-19-2008 03:32 PM

Re: WFO Progressing Nicely, but Help Needed.
Are you planning on a chimney? If not, plan on smoke out the front. What about a door too? Which method will you use for curing, old or new per James?

jeff 01-20-2008 05:37 AM

Re: WFO Progressing Nicely, but Help Needed.
Vermiculite is just a big word for Kitty Litter. (Possible joke there, eh; but they do look similar. [I think.]) Long time since our last live-in kitty.
Mate, I'm a Newbie. Captain Ignorant to you, Sir.
These ovens are serious shit: first cousins to potter's kilns, which, in turn, are first cousins to blast furnaces. So no, fire-retarded house insulation is not really a viable option.(IMHO)
Mate, for ceramic blanket, check out your local pottery suppliers.
And I stand corrected: my roll of 25mm blanket was A$145, plus $35 freight.And a double layer would not be money ill-spent.
(What part of the UK do you call 'home'? Our Daughter is in London now. Bizarre.)
Good hunting eh.
Ludd the Jeffite

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