Heat Drops fast!

[dimitrisbizakis]

Re: Heat Drops fast!

If you had used dense firebrick for your floor and dome, after a two hour burn the oven temperature would be in the region of 400 C

What do you mean if?
I'm not the guy with insulation firebricks m8
I have build my dome with solid red clay bricks and floor with firebricks.
At firing the temps rise up to 500 c, perhaps moister is still there and I have to be quicker with the coals racking out...
When is the perfect time to remove the coals without losing to much heat?

[david s]

Re: Heat Drops fast!

Sorry, I got you mixed up with Tonybaker's oven. Have you got insulation under your floor? A new oven contains a lot more moisture than you would think and it takes a lot longer to drive it out than you would think. If you've only had two fires in it then that is insufficient to remove all the water. Keep firing and cook some stuff in the oven like roasts and bread, forget pizzas for now. You should start to notice an improvement in the ovens performance, ie. less smoke, quicker temp rise and more even heat distribution. It sounds like the top of your oven may be dry while the bottom and floor is still moist.

[dimitrisbizakis]

Re: Heat Drops fast!

Sorry, I got you mixed up with Tonybaker's oven. Have you got insulation under your floor? A new oven contains a lot more moisture than you would think and it takes a lot longer to drive it out than you would think. If you've only had two fires in it then that is insufficient to remove all the water. Keep firing and cook some stuff in the oven like roasts and bread, forget pizzas for now. You should start to notice an improvement in the ovens performance, ie. less smoke, quicker temp rise and more even heat distribution. It sounds like the top of your oven may be dry while the bottom and floor is still moist.

Today, after 7 hours, the oven was at 100c, that is without embers inside and with the door on.
Em i supposed to leave the door on?
I have a thought that the moister would not have a way out.
And another question, do you wait for all the wood turn in to embers and the you rack them out?
I'm saying that because after i throw 2 pieces of 4 cm of olive wood on each side of the oven, they ignite of course but after a while the just stopped burning.Fearing that the heat will start dropping because the fire went off, i remove them so the embers and closed the door.

[brickie in oz]

Re: Heat Drops fast!

they ignite of course but after a while the just stopped burning.

The ovens wet.

[david s]

Re: Heat Drops fast!

Today, after 7 hours, the oven was at 100c, that is without embers inside and with the door on.
Em i supposed to leave the door on?
I have a thought that the moister would not have a way out.
And another question, do you wait for all the wood turn in to embers and the you rack them out?
I'm saying that because after i throw 2 pieces of 4 cm of olive wood on each side of the oven, they ignite of course but after a while the just stopped burning.Fearing that the heat will start dropping because the fire went off, i remove them so the embers and closed the door.

It sounds like the cause of your issue is the 30 cm of vermicrete under the floor, which is probably still wet. As the base of the dome and the insulation under the floor are the hardest to dry out, try spreading the fire to the base of the dome and just keep feeding it all day if possible. If it's wet down there you will probably notice a persistent ring of black soot which is also an indicator that the oven is still wet there.
If you are trying dry the oven leave the door off and the coals in.

[dimitrisbizakis]

Re: Heat Drops fast!

The ovens wet.

...damn!Curing fires are so boring...

[dimitrisbizakis]

Re: Heat Drops fast!

It sounds like the cause of your issue is the 30 cm of vermicrete under the floor, which is probably still wet. As the base of the dome and the insulation under the floor are the hardest to dry out, try spreading the fire to the base of the dome and just keep feeding it all day if possible. If it's wet down there you will probably notice a persistent ring of black soot which is also an indicator that the oven is still wet there.
If you are trying dry the oven leave the door off and the coals in.

I will try your advice my friend, thank you for your help.

[Laurentius]

Re: Heat Drops fast!

...damn!Curing fires are so boring...

Then, cook something while you're curing!

[MAVANO]

Re: Heat Drops fast!

excuse me dimitri you used red clay bricks for dome , is that not going to spall in high heat

I was under the impression that red clay bricks spall under high heat, I told someone this and they said no they will not can someone explain? plus he is using bricklayer's mortar, which is portland sand lime mix could this work?

[dimitrisbizakis]

Re: Heat Drops fast!

Then, cook something while you're curing!

I have a problem retaining the heat to cooking temps because of hydration.
Untill all moister is out i just look the oven as a fireplace!!!

[cobblerdave]

Re: Heat Drops fast!

excuse me dimitri you used red clay bricks for dome , is that not going to spall in high heat

I was under the impression that red clay bricks spall under high heat, I told someone this and they said no they will not can someone explain? plus he is using bricklayer's mortar, which is portland sand lime mix could this work?

Gudday
Good quality pressed clay commons and pavers are suitable for WFO there's a lot out there particularly in aust. If you cant find firebrick or its unaffordable they are the next choice.
With the mortar mix the Portland cement tends to fail at over 300C but serves the purpose of Holding the mix together at the start. The lime sets over time with the heat and provides the long term higher heat "glue" in the mix.
Regards dave

[dimitrisbizakis]

Re: Heat Drops fast!

excuse me dimitri you used red clay bricks for dome , is that not going to spall in high heat
I was under the impression that red clay bricks spall under high heat, I told someone this and they said no they will not can someone explain? plus he is using bricklayer's mortar, which is Portland sand lime mix could this work?

When you say high heat, what temps do you think the oven will get, assuming that you will make good use of fuel, and in what temps pure clay is kilned?
Of course the bricks are solid without holes and without concrete addition.
Here in Greece we have 130 years old oven that was built with red clay roof tiles and clay mortar or lime with sand.
After a successfully build Cob Oven(that is clay and sand) with at least 300 fires that some times reached 500 c and no spall at all, i was convinced that there will be no problem with plain red clay bricks for the dome of the oven.
Of course i have used firebricks on the hearth only because are more durable than red clay bricks.
Using bricklayers mortar is not so weird to me because concrete mortars in wood oven suffer from high heat only on the face of the mortar that looks directly to the fire.
I have used the poor man's refractory mortar 3 fine sand, 2 lime putty, 1 Portland cement and 1 clay and so far i haven seen and problem.
Keep in mind that the price of the red clay bricks is the 1/7th of the firebrick.
I have bought 0,20 a piece and the same dimensions firebricks costs 1,5 euro.
The downside is the low thermal mass, dense firebricks keeps for longer the heat but until now, without fully cured oven and two firing's in two days, the third day and after 12 hours with the coals removed and the door shut, the oven is at 150 c!
So i thing we're good!!!

[brickie in oz]

Re: Heat Drops fast!

I have a problem retaining the heat to cooking temps because of hydration.
Untill all moister is out i just look the oven as a fireplace!!!

So steam something in it.....

[brickie in oz]

Re: Heat Drops fast!

When you say high heat, what temps do you think the oven will get, assuming that you will make good use of fuel, and in what temps pure clay is kilned?

I get my oven to at about 600c prior to a pizza night, Ive had it to 800c, clay bricks are fired to about 1200c, so clay bricks are good for ovens.

Ive laid some dry pressed red clay bricks that weight 4kgs each so density shouldnt be a problem.

[dimitrisbizakis]

Re: Heat Drops fast!

So steam something in it.....

Hahahaha...steam bath time!