|
|
Post by thebogman on Aug 1, 2020 13:10:26 GMT
Thank you for this amazing forum, I've spent night reading about and and looking at the amazing builds. The word inspirational gets bandied about but this forum is. Not ready to build yet but I have a cracking site on a disused solid concrete water tank and a supplier, Dineen Refractories, 40km/25 miles away.
There's a vast, vast amount I don't know and the scarier bit is the unknown unknowns because I'm utterly virgin ignorant.
So far I've gathered:
⭐ Hollow base, drier and very handy wood storage
⭐ Insulation, Insulation, Insulation!
⭐ Flue at 63% of dome height. That's dome top to oven floor? Irrespective of maybe two straight layers of bricks before the beehive shaping?
If I build the inside from firebricks does that look after the thermal mass?
What's an "IT pivot"?
I'll need to create an insulated door too, not letting all that heat go to waste but should there be some kind of flue stop in the chimney for that to?
Is chimney height an issue? (I like the ovens where the flue doubles back over the dome and there's a central chimney!)
Paddy
|
|
|
|
Post by thebogman on Aug 2, 2020 21:34:10 GMT
Duh! IT = Indispensable Tool!
|
|
|
|
Post by thebogman on Aug 2, 2020 22:53:43 GMT
Tinfoil over the ceramic blanket? If it was pierced to allow steam out? Tinfoil behind radiators increases efficiency by around 6%. Probably can't put it underneath the blanket because it might melt but above, before the vermcrete layer? I'm going to be planning this for a long time!
|
|
|
|
Post by downunderdave on Aug 3, 2020 1:03:59 GMT
When you say tin foil I presume you mean aluminium foil. Melting point of aluminium is 660C so no worries there, but it does act as a vapour barrier if not perforated. Also, as aluminium is highly conductive it is useless to prevent conductive heat loss if sitting against conductive refractory, brick or the outer cement shell.
|
|
|
|
Post by thebogman on Aug 3, 2020 1:51:04 GMT
Sorry, yes, aluminium foil,reverting to its name in my childhood!. I only want it to reflect heat, planning on using ceramic blanket and vermcrete to deal with conduction. 660 would mean I could use it under the blanket.Not a big cost so worth trying I think.
|
|
|
|
Post by downunderdave on Aug 3, 2020 6:36:57 GMT
Sorry, yes, aluminium foil,reverting to its name in my childhood!. I only want it to reflect heat, planning on using ceramic blanket and vermcrete to deal with conduction. 660 would mean I could use it under the blanket.Not a big cost so worth trying I think. As you wish, but pretty useless under the blanket against the dense inner dome. If it’s not already perforated put plenty of holes in it. |
|
|
|
Post by thebogman on Aug 3, 2020 9:11:59 GMT
No point if it's useless!
|
|
|
|
Post by downunderdave on Aug 3, 2020 20:08:50 GMT
No point if it's useless! When I built my oven 12 years ago I covered the vermicrete layer with foil thinking it would prevent moisture being sucked away from the outer rendered layer applied over it. before applying the render I thought it may be a problem holding moisture in so I perforated the foil in two places about 8 sq in in each area, one at the top of the dome and another about 3/4 up from the base. Now when I fire the oven after prolonged rain or even after a couple of weeks of humid weather without rain (we live in the tropics) The outer shell in those places gets quite hot while the rest of the dome is barely warm. What must be happening is steam is finding its way through those perforations. This is interesting, but would also make the drying of the insulation slower. Therefore I no longer use foil in subsequent ovens I build. Now, to hold moisture in the outer rendered shell to enhance strength, I wrap the whole oven in cling wrap and leave it for a week. This is a pretty good solution and has been working well for me for years. |
|
