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Post by oblertone on Jun 3, 2020 18:39:42 GMT
I used clay bricks in mine and it's shown no sign of degradation over the last five years; however, the bricks were 200yr old 'solids' from a neighbours dismantled chimney, if yours have frogs (indents) or holes through them then the advice would be not to use them. Solids can be found at reclamation yards and as you're going to split them anyway damaged ones are fine and may be cheaper.
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Post by oblertone on Jun 3, 2020 10:16:35 GMT
As you've discovered you need to insulate the cooking floor and there are a number of options; thermolight blocks laid on their sides will provide a 10cm insulating layer. Vermicrete is another option but needs to be left to dry out before covering, insulating board is thinner but very effective albeit more expensive. folk have also used wine bottles lain in mortar but i've no idea how efficient these are. I used 25mm thick vermiculite sheet but mine is in an enclosed tray.
Remember that cooking floor height is critical and should be at the elbow height of the main user, therefore your choice of underfloor insulation may be dictated by this.
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Post by oblertone on May 31, 2020 10:52:32 GMT
Calcium silicate insulation; seems to tick all the boxes, give it a go and let us know how you get on.
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Post by oblertone on May 31, 2020 10:49:27 GMT
A cheap gazebo from eBay provided welcome shade and kept me dry while working on mine.
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Post by oblertone on May 31, 2020 10:48:14 GMT
Have a quick measure because the rule of thumb is that the cooking floor should be around the same height as the elbow of the main user; use blocks to suit.
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Newbie
May 31, 2020 10:46:22 GMT
Post by oblertone on May 31, 2020 10:46:22 GMT
Build it yourself, study some of the archive builds on here, mostly done by complete beginners. Ask lots of questions too.
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Post by oblertone on May 27, 2020 17:49:08 GMT
Think about it logically, storage heater blocks are designed to store heat energy, not act as an insulator. Using two layers will mean your heat will migrate and you'll have to store twice the energy to get up to temperature, which is hard enough anyway. Use one layer, and insulate underneath it would be my advice. Thermolite building blocks are a cheap alternative to vermiculite board.
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Post by oblertone on May 25, 2020 19:44:54 GMT
I bought my vermiculite sheet from eBay but doubtless there are other sources, try a stove shop as that's what they cut firebricks from to reline stoves. Lime you can get from any builders merchant, clay can be more tricky but I ended up using a pottery supplier.
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Post by oblertone on May 24, 2020 17:19:48 GMT
Oven floor bricks should be laid loose in case you need to replace one, a scattering of sand underneath will help you get them level; the gaps will fill with ash after the first firing and no-one will notice. Between the floor bricks and the soldier course it is common to place a ring of cardboard to ensure an even gap and stop your mortar gripping the floor bricks. It is even more common to lay the soldiers first then cut the floor bricks to suit, but either way works.
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Post by oblertone on May 23, 2020 17:15:36 GMT
First, don't use fire cement, it's expensive and unecessary; use 'home-brew' which is Sand/Cement/Clay/Lime in the ratio 3-1-1-1. It is cheap, forgiving to work with and perfect for a WFO.
As to your base layers, your cooking floor should be about 2" thick, this needs isolating by an insulation layer (vermicrete) and this insulation should meet the insulation over the dome. What these two layers sit upon is largely material as it won't be used to store heat, con-blocks are commonly used. The cooking floor can be made of refractory bricks or even storage heater blocks, but it must be a layer capable of storing heat without degrading.
Having built the stand and allowed time for the vermicrete to dry out, then the floor bricks can be loose laid on a bed of sand for levelling, no mortar required.
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Post by oblertone on May 23, 2020 17:05:19 GMT
Welcome to the site, you'll be given all the advice you need if you just ask. Before you start cutting wood it's worth noting that the cooking floor of your WFO should be at the elbow height of the main user; that'll give you a rough idea how tall your form needs to be.
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Post by oblertone on May 23, 2020 17:02:36 GMT
Forget fire cement, it's meant for furnaces and kilns where temperatures exceed 900c, your WFO will only get to around 550c so fire cement is an expense you don't need. Instead, use 'home-brew' which is Sand/Cement/Clay/Lime in the ratio 3-1-1-1 by volume, cheap, easy to use and perfect for WFO.
The rest of your plan appears sound, the aim is encapsulate the oven in insulation, how you go about that varies from build to build but it's the goal you should strive for.
I used vermiculite sheet below a layer of heater blocks and it has worked well for me so far.
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Post by oblertone on May 22, 2020 8:59:19 GMT
... although it doesn't say which flour they used; this must surely rate as a gadget  |
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Post by oblertone on May 22, 2020 8:57:21 GMT
The dome of your oven may well exceed 300kgs, if you're comfortable with the thought of that collapsing then crack on, if not add support ! Paranoia rules but better safe than sorry ...
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Post by oblertone on May 19, 2020 16:54:51 GMT
I'm afraid to admit that all I've ever used is Allinsons 3kg bags of strong bread flour from Tesco and standard plain flour in the ratio 2-1, with a handful of fine semolina thrown in for a bit of crunch.
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