Aussie Oven Upgrade

[juddy]

Greetings from South East Australia.

I have been lurking around this site and others for years now, however this is my first post. My interest in Wood Fired Ovens first started around 7 years ago when I was inspired by the Russell Jeavons book, "Your Brick Oven" to build an oven to his design. What resulted was an oven built of recycled red clay bricks on an uninsulated slab supported by Pine stumps. The dome of the oven was very lightly insulated and would get to hot to touch. For all the 'errors' I made with this oven it still worked a treat and resulted in about 6 years of pizzas, roasts and bread. And whats more, It didn't collapse and the pizzas weren't full of mortar! I was so taken by this little oven that I also helped around 5 friends and relatives build theirs!

The Wood Fired bug had well and truely bitten though and deep down I wanted to try and build a higher spec, bigger and more efficient oven. I was greatly impressed by the Rado Hand ovens of traditionaloven.com and ordered his DVD. Before i knew it the location had been cleared, the ground slab was poured (all by hand), and the concrete block supports for the insulated hearth slab were laid and concrete filled. The form work for the hearth slab was constructed and the insulation set before the concrete hearth slab was poured (again by hand).
More to come...

Juddy

[juddy]

Re: Aussie Oven Upgrade

Greetings again.

The next step was the oven wall and vault construction. I had acquired the firebricks for the dome at less than ? the price that most retailers were quoting. It pays to ring around. I needed around 230 firebricks and had been quoted up to $4.40AUD per unit!!! Calcium Aluminate Cement was used for the bonding of the firebricks. The firebricks were a joy for a novice brickie like me to work with. They were relatively ?true?, and before long the rear and sidewalls were completed. The firebrick walls were then supported from the inside of the oven (by formwork) and the concrete cladding was poured for the sides of the oven. This in turn gave me the base to start building the vaulted roof of the oven.

The oven has a vault height of 480mm, width of 860mm. There were 4 full brick width arches, and one ? brick width arch. Each arch was made up of 14 bricks. The oven entry arch was built out of 9 50mm splits resulting in an entry height of around 300mm.

There?s still more?

Juddy

[brickie in oz]

Re: Aussie Oven Upgrade

I think you must have had the plan upside down, the insulation is supposed to between the oven hearth and the concrete slab.

[chidding]

Re: Aussie Oven Upgrade

I think you must have had the plan upside down, the insulation is supposed to between the oven hearth and the concrete slab.

Agreed..

i really think you should read the pompeii plans available on the forno store (free)..

Surely it makes logical sense though right? insulation next to the hot part?

[juddy]

Re: Aussie Oven Upgrade

Howdy

Interesting comments that sent me scrambling for my DVD of oven plans. The DVD contains images of 2 types of vault ovens being built. Both a very similar in design. I then read and re read the instructions that are on the disc. It would appear that I have placed the insulation in the right place. These ovens would appear to be on the high side of the thermal mass scale. So the idea was that the vermiculite would insulate the large mass of the fire brick base, and the concrete hearth slab from the void below. The entire oven has the same wall/floor thickness i.e half a fire brick then either concrete cladding/hearth slab, and finally this entire thickness is insulated. If the insulation was between the fire brick base and the hearth slab wouldn't I miss out on all the thermal mass of the hearth slab?

Cheers

Juddy

[brickie in oz]

Re: Aussie Oven Upgrade

Unfortunately most of the heat will leak out of the oven via the concrete slab and down through the slab support.

[juddy]

Re: Aussie Oven Upgrade

Hey Doug

That makes sense to me. I still have the original oven, and it will be great for pizza nights where you want a quick fire up. The Rado oven will be used for mainly baking bread. Part of the fun of this new oven was to build an oven that is at the other end of the spectrum to the original. One is a dome, one a vault. One secondhand clay bricks, one firebricks. One poorly inslulated, one highly insulated...

Once the oven is finished curing I will be able to compare the two effectively side by side.

After a curing fire the other night the dome temp in the new oven was around 170 degrees C. 48hrs later and the dome temp was around 90 degrees C. So I am hopeful that the greater thermal mass and increased insulation will create a great baking oven.

Cheers

Juddy

[juddy]

Re: Aussie Oven Upgrade

Hello again.

Once the oven vault and entry was complete I could clad the exterior of the oven in concrete. The forms were built out of melamine and concrete reinforcing was used throughout. Again all the concrete was hand mixed and poured. Once this was finished the brickwork surrounds could begin.

Now a brickie I am not! I found this part of the job extremely hard, and its fair to say that I?m a little disappointed with the results. All along the exterior of the oven was going to be finished in a ?rustic? style and thank god for that. Because now some of my dodgy bricklaying skills can be passed off as an attempt to create that ?rustic? appearance!

Still more?

Juddy

[brickie in oz]

Re: Aussie Oven Upgrade

Al, not quite true the insulation under the hearth is to stop the cooling via the void under the slab,

I had a similar set up on my old oven and ppl used to hug the sides of the oven to keep warn on cold nights, it stayed at 60 c so obviously was losing heat through the sides.

[chidding]

Re: Aussie Oven Upgrade

Was the oven insulated ontop ? or is that just cement?

[juddy]

Re: Aussie Oven Upgrade

Hey Chidding

The oven as shown in the last post is unfinished. I have been away for a few days so I couldn't quite finish posting the construction pictures. The oven itself is surrounded by a brick facia, and the void between the 2 filled with masses of insulation. I detail that below...

It was now time to start thinking of the insulation for the oven. I had started the curing process and the small fires showed that the oven drew beautifully and the fires burned well. The area between the concrete blocks and the brick surround was filled with compacted earth up to the base of the slab. From there the whole oven is encased in vermiculite insulation, and the area between the vermiculite and the roof filled with R3.5 woolen insulation bats.

Cheers

Juddy

[juddy]

Re: Aussie Oven Upgrade

Greetings.

The final stages involved the fitting of the corrugated iron roof and flashings. And painting of the dodgy brickwork. The curing fires are continuing, and so far there is no cracking. The oven would appear to hold its temp exceptionally well and I look forward to testing this further once the curing is complete. The oven door is built of solid Mountain Ash and fits snuggly in the oven opening, keeping moisture and nasties out when not in use, and heat in when baking. So I look forward to hitting the cooking zone in the next few weeks, and will be sure to pass on the results.

Cheers

Juddy

[juddy]

Re: Aussie Oven Upgrade

Hey Doug

Thanks for the kind words. The original oven still stands in the middle of the rear yard, and it is surrounded by veggie gardens, and a chook shed at the rear. It will stay on as a bit of a relic in the yard. When we moved into the new house it was the first thing I built in the rear yard, and truth be known it was not in a good spot! To far from the house, and no protection from the elements! Still had plenty of good nights with it though, and it cost me next to nothing. I've included some photo's of the oven and I have plenty more to show if anyone is interested. It's a little sad to see it looking down the yard to the new oven but I'll still probably use it occasionally!

Cheers

Juddy

[Onefella]

Re: Aussie Oven Upgrade

Hi Juddy, nice looking oven mate. I see the "pompeii-or-nothing" crowd got on your case pretty quickly. I had a similar response when I first posted about my vault oven.

My Alan Scott vault works amazingly well, and has done ever since we started using it. I originally wanted a bread oven, and that's what it excels at. I can do three full loads of bread on one firing.

Of course it smokes, does pizza, roasts and cakes just fine too.

[juddy]

Re: Aussie Oven Upgrade

Hey Onefella

I guess I'm lucky enough to have one foot in each camp now.

I found that my Pompeii style oven was awesome for pizza, but lousy for bread and baking. That had little to do with the oven shape but more to do with the way I built it. i.e not enough thermal mass, and not enough insulation.
I have cooked a roast and pizza in the new oven and its great to use. I would describe the new oven as being more stable. It is predictable to fire to a desired temp, and equally as predictable to maintain and bake in. Which is exactly the characteristics I was after.
I found that the older dome oven with its thinner walls and insufficient insulation was very temperamental and things such as wind direction, drafts and ambient temp had quite an effect on its performance. Nothing new in that I guess.
Today I am going to fire the new oven for a pizza dinner, and then hopefully tomorrow I will bake my first load of bread. Cant wait...

Cheers

Juddy