Clydebank Build

[nixie]

Your chimney dimensions should be between 5 and 6 inches.

think I might have gone overboard for a 32" oven then!

[swatson]

Thanks Terry, I'm gonae do a bit of scavenging to see what I can find if fruitless will just make a shaped hole of oven mud with a slightly raised lip between oven and arch.

[swatson]

Thanks for the link info seems to be working now!

PS
For the insulation layer any idea what weight I need to buy of straw/sawdust, on a very tight budget and don't want any extra if possible?

[swatson]

It's been a busy few weeks so haven't been able to keep posting progress so here's a few pics of what I've been doing!

[swatson]

Dried out oven using progressively bigger fires!

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[swatson]

I decided that I wanted a brick archway to help protect the opening, so built a sand former and covered with newspaper. Then built an archway over the sand former using some oven mud mix as mortar and driveway mono blocks that one of my neighbours had left over. I used a sheet of plywood and a brush handle proped against my decking to keep the sand former firmly in place.

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[swatson]

Once I was sure the bricks were firmly set I removed the plywood support. This pic shows the archway with the sand former still in place.

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[swatson]

And the completed archway!

Pretty happy with the finished article, though I must have applied some downwards pressure on the top as the two uppermost bricks are slightly out of line with the rest of the arch!

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[swatson]

I have left a 5" hole between the arch and the dome as I intend to add a chimney over the next week or two.

I fired the oven up for its first cook last week and found it took well over 2 hours to get to a decent temp and even that only allowed 5 min cooks. I'm hoping the insulation layer will allow it to retain much more heat resulting in quicker start ups and longer retention of heat once cooking commences. Would a firing door also help?

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[nixie]

Looking good. Hows the firing going, any cracking?

[swatson]

Firing has been good with only minimal cosmetic cracks that only showed up on my first bake, you can see them on the final pic above where the chimney will be, this was when I loaded the oven with wood to the point the oven roof was reading 'high' on the infared which has a max temp of about 1050!

[nixie]

Do those open up at all under load?

[swatson]

No they they remain as they are throughout, or at least I haven't noticed any changes during a firing/cooling cycle.

[bookemdanno]

You'll need several good fires before you get full performance. There's a lot of retained moisture that needs driving out, and then after each winter (if you don't use it) you'll need to season the oven again to drive out any damp. The moisture means that the heat doesn't hold as the water acts as a medium to draw the heat out.
It'll get better the more you use it.

[swatson]

Bookemdanno,

Once I put on a 3-4" insulation layer of clay and sawdust how much more heat is retained? It takes over two hours at present to get up to heat how much would that reduce by?