Sooty Dome

[nick2013]

I'm on about my 4th firing, cooked some pizzas (very nice), the temp reaches about 250 -300

I don't seem to be able to get the fire hot enough to burn off the soot and get the dome white hot, any tips \ advice

I'm I getting ahead of myself, is it still drying out ? Time of year ??

Thanks

[muddy4x4]

I have a modular oven that didn't need drying out, but from my experience, the dryness of the wood you are using makes a very big difference. Get some good kiln dried wood and have another go. I had some seasoned wood a while back, burnt well, but struggled to get much over 300, as soon as I got some good kiln dried, up to nearly 500.
As silly as this may sound, wind direction can also make a difference, or it does to my oven !
Good luck !
Muddy

[bookemdanno]

There are many factors to take into consideration here Nick.

There will be moisture within the structure, this could slow things down and cause heat loss.
The oven will only take on heat at its own rate, you could have a massive fire in there and it'll all go up the chimney. You might need to have a longer burn to your fire. You didn't mention how long your burn was.
I couldn't see how much insulation was applied to your oven also from the build blog, this could also be a factor. Along with what Muddy said too, the wood quality makes a difference.
An oven will take several fires to get to full performance, and a damp winter with no use will mean that you'll be back to square one again too. Come the spring, you'll need to drive out the damp and cold.
Its a relationship that you'll now have to build, and get to know your new friend in the garden. Keep going, and don't forget that you don't need to pay extra for kiln dried wood, as you have the perfect tool right there. Just fill your oven with wood after each firing, when the oven has cooled a bit.

[nick2013]

Thanks, I'm maybe getting a bit ahead of myself with the drying out process, here's a run down on insulation:

Under the dome: 25 mm calsil board, with fire bricks directly on top.

Modular dome (70mm thick), sealed with fireclay, 25 mm insulation blanket, 30 mm vermicrete, rendered finish.

The last two firings were over a period of 5/6 hrs.

[cannyfradock]

Nick

Here's my twopenneth worth......

It sounds like you have the correct insulation under...and over the oven for it to function well. You should be getting more heat from the oven....and (especially if it's a professional modular oven)...you should see, by now after your curing fires, the soot start to clear from the top of the dome after no more than 30 or minutes. (I know that with my modular oven (mobile oven from Dingley Dell) after about 30 or 40 minutes you can clearly see the line of soot descend down the wall of the dome. When it reaches about 6 inches from the bottom, I then spread the cinders over the whole base for about 15 minutes then push them to the side. I then usually have to wait a further 20 minutes or so for the oven to cool enough before I put the first pizza in.

Apart from the previous comments (dry hardwood etc) the culprit could be the position of the vent. A lot of the modular ovens from the continent have the vent on the inside of the oven, but most of the imports have a damper system on the chimney. ( a sliding plate which blocks off the chimney and keeps the heat inside the oven).....if your's hasn't got one, you may have to create one....it's not the best design, but as they sell an awful lot of these ovens to the UK market......they should work regardless.

Had to look back over your oven build to see what type of oven you had built....and love the finish you made to your oven. Really hope it comes right for you.

Terry

[Tom B]

Nick
I fully agree with the comments about the quality of the wood and how it should be properly seasoned and dried. It took me about 3 weeks to fully cure my IF oven with small fires using just kindling to start with (half a kilo) and gradually building up the amount of wood used until I went for the full burn, and the soot cleared for the first time after about an hour. The second full burn and the soot cleared after about 40 minutes, and stayed that way. And you do have to slightly cure again after cold and wet winters. Stick with it - once you have a good fire going get the wood to the back or side of the oven and let the intense flame play over the roof of the oven.

[nick2013]

Thanks for all your comments, I'm certainly taking them on board, I have a small fire burning at the moment and some wood drying on the other side, for the next burn.

It's been quite wet here and very still, so not much draw for the fire, I have had some good pizzas so far, but looking forward to getting this oven full blast, I shall stick with it !

[nick2013]

Good News and Bad News ....

Good news being the dome went white and the temperature increased, so I'm on the right path, I've noticed some cracks round the chimney. Bit of an issue here as I didn't put in a fire break, so thinking of digging the chimney out and either replacing with a twin lined flue or using a chimney pot with the flue inside it ?? What do you think ?

The bad news, I managed to hit the base of my thumb with an axe, while chopping up kindling, so a trip to A&E was needed, glue and stitches, two hours later was back home. Worst thing was that everyone got a lovely pizza out of the oven, apart from me, when I got back the fire had died down, so my pizza was cook conventionally indoors !

[moonhead]

So I'm not the only one knocking my thumb with the axe! Luckily I had a pair of leather gloves on so damage was limited to loosing a chunk of skin. When I'm chopping larger pieces I place the axe where I want to cut and hit that with a 3lb hammer - the axe not my thumb! much safer. Lesson learned for next time.
Bad news about your pizza though, I bet that hurt even more.

[cannyfradock]

Nick

Sorry to hear about the missing digit.....still, you,ve got another 9 so no need to worry....only joking...hope the flesh wound heals up nicely.

Nice to hear that the oven is firing up as it should. You've probably....through your previous firings and party's managed to push ALL the moisture out of your oven.

It would be a good idea to make a "chase" around the chimney where the render is directly against it. A small gap can be filled with fire-cement or fire-mastic. If you open a larger area when trying to do this, then you could fill with vermercrete. Cracking around the chimney won't affect the performance of the oven but ...once the oven has cooled after use, try to cover this area to protect from water penetration until you get round to doing a "fix"

Terry

[bookemdanno]

When splitting kindling, hold the piece of wood you're wanting to split by taking a piece of timber in the free (non-hatchet) hand and catch the top edge of the piece to be split when its standing up. Pick up the hatchet and split away, knowing that all digits are at least 6" from a sharp edge.

If you're splitting logs, get an old tyre, lay it on its side on your block, fill with logs and split away!
All the logs stay inside the tyre, no flying timber, and all fingers are a long way away!