What is wrong??

[Filthymutt]

Ok, Curing fires are done. Are done. Its ten days since I closed my dome and I'd lit several small fires during the process, ALL WITHOUT INSULATION to check for cracks/leaks, etc.

So I had a fire going at 625C (1150F) today. Oven is not going white, and things aren't that hot. What I mean is I measured the temp of the bricks a foot away from the edge of the fire and they are only hitting 75C ! The wones 1/2 a foot away are hitting maybe 125C. Even the top of the dome is only 3-400C

So, whats up? Am I measuring the heat of the fire wrong? Cause it was not a scary fire as I've heard the term bantered about. I used the laser thermometer and got that temp from the center bottom of the burn.

Is the heat not spreading because of lack of insulation? Shouldn't be because I felt the outside of the dome with my hands, in many different spots and it wasn't hot or even warm an hour into the burn.

I'd about 3 logs going. What is wrong? I need to burn like 6 or 7 big pieces of wood or what?

Thanks all.

Frustrated Bob

[stonecutter]

Re: What is wrong??

Ok, Curing fires are done. Are done. Its ten days since I closed my dome and I'd lit several small fires during the process, ALL WITHOUT INSULATION to check for cracks/leaks, etc.

So I had a fire going at 625C (1150F) today. Oven is not going white, and things aren't that hot. What I mean is I measured the temp of the bricks a foot away from the edge of the fire and they are only hitting 75C ! The wones 1/2 a foot away are hitting maybe 125C. Even the top of the dome is only 3-400C

So, whats up? Am I measuring the heat of the fire wrong? Cause it was not a scary fire as I've heard the term bantered about. I used the laser thermometer and got that temp from the center bottom of the burn.

Is the heat not spreading because of lack of insulation? Shouldn't be because I felt the outside of the dome with my hands, in many different spots and it wasn't hot or even warm an hour into the burn.

I'd about 3 logs going. What is wrong? I need to burn like 6 or 7 big pieces of wood or what?

Thanks all.

Frustrated Bob

How long was the fire going when you felt it with your hand? Is there cladding on the oven? Are you sure that it is cured? Is the oven protected by the weather?

If anything, insulation help distribute the heat within the masonry a lot faster. It sounds like you still have a wet oven .

[thickstrings]

Re: What is wrong??

Don't know what kind of wood you are using, or how long the fire is burning, but, I use 7-8 pieces of dry oak,12-16", from wrist to bicept size and a handfull of kindling. It will take about 1-1 1/2 hrs to get to white in a 39" insulated oven..I think that you need more wood...if your dome is dry. I would insulate, soon. Really hot fire in a uninsulated dome will get the top hotter, much hotter than the rest....insulation will "temper" the heat and help to distribute, unifiy the heat minimizing temp. differences......and cracking... And what Stonecutter said above...it may still be wet....the insulation will help move the heat and drive out the moisture...

[boerwarrior]

Re: What is wrong??

when you say the fire is at 625C (1150F) where are you measuring that?

If you are pointing your heat gun at the coals then that is not a very hot fire. When my fire is burning I can get the roof of the dome up to 1100 degrees F and my heat gun (which maxes at 1400 degrees F) cannot measure the heat of the coals...

[deejayoh]

Re: What is wrong??

takes 90-120 minutes for a cured oven to clear. Your new oven will take longer and probably more wood. Just keep stoking the fire. And 3 logs is not many. My 39" takes 4-5 logs going to clear

[Filthymutt]

Re: What is wrong??

Thanks all, Yup, once I get the enclosure done and insulation in (can't get a blanket here gong to fill the enclosure with loose vermiculite) then I will go much hotter.
I was measuring at the coals 625C after 3 pieces of wood.
And was not waiting long enough.
Impatience, is always my downfall

I'll burn today but I won't try going too hot until the insulation is all in.

[mrchipster]

Re: What is wrong??

Measuring the temp of the coals will always give you a high reading it has nothing to do with the brick.temps,

[Les]

Re: What is wrong??

Is the heat not spreading because of lack of insulation?

The heat isn't spreading because fire brick is a crapy conductor of heat. You can get the oven incredibly hot without the insulation, it just won't retain the heat. BTW, 3 pieces of wood is weak. Get that sucker going with the fires of hell - flames jumping out the top and the entry (very cool to watch).

[brickie in oz]

Re: What is wrong??

BTW, 3 pieces of wood is weak. Get that sucker going with the fires of hell - flames jumping out the top and the entry (very cool to watch).

Thats the way......

Sounds like the oven is still wet.

[Filthymutt]

Re: What is wrong??

Success! Finally got hold of Calcium Silicate blanket and went overkill on it with 150 sq.ft. worth. Fired up the oven at least a dozen logs worth. Cleared the dome! But I'm still wondering about temps. The heart of the fire, in the coals is only about 630C (1166F) and my hearth bricks adjacent to the fire top out at 300C (572F).
Is that as high as it should get?
I burned and kept it stoked for four hours. Closed the door on the coals about 9:00pm. This morning made Blueberry muffins in there. Closed the door again and reheated leftover pizza tonight 26 hours after the original firing without a relight. Amazing heat retention.

Bob

[mrchipster]

Re: What is wrong??

It will even get better overtime with a good insulated door. The heart of the fire is not important, the temp of the bricks is, and once you get the oven fully dry you may see even longer heat retention.

Mine is still 106 F today and I cooked twice since I had fire, once for some chicken and once to bake bread, fire was 8 days ago and average ambient has been about 55F - 40's at night and 70's in the daytime.

[Filthymutt]

Re: What is wrong??

It will even get better overtime with a good insulated door. The heart of the fire is not important, the temp of the bricks is, and once you get the oven fully dry you may see even longer heat retention.

Mine is still 106 F today and I cooked twice since I had fire, once for some chicken and once to bake bread, fire was 8 days ago and average ambient has been about 55F - 40's at night and 70's in the daytime.

Wow, 8 days ! Amazing!

Can you tell me how hot the floor bricks should be getting optimally ?

Well thus far I have made a rudimentary door cut from a leftover sheet of calcium silicate board. And I left a gap at the bottom for a little air flow. The gap is an inch high/ten wide. The door to sheets thick, so less than an inch. I'm going to remake the door, double thick plus a wooden outer skin. With a thermometer. But what of the gap, necessary ?

Bob

[boerwarrior]

Re: What is wrong??

My floor bricks right next to the fire get to about 800 degrees. That is too hot to cook pizza on so I push all the coals to the side and normally wait about 30 minutes before cooking. I suspect your oven is still a bit damp which is why the floor is not getting any hotter yet. If you are clearing your dome then the roof and wall temperatures are correct.

Well done! Keep at it - I'm sure you will get your floor temperature up with time.

[oasiscdm]

Re: What is wrong??

Hey chipster

That's amazing cooking 8 days after a firing.


No top up firing required.

[mrchipster]

Re: What is wrong??

Hey chipster

That's amazing cooking 8 days after a firing.


No top up firing required.

Not sure i can find anything that will cook at 108F but I guess I could be dehydrating something.

I could be doing some smoking, I guess, but it would need to be something safe like cheese or nuts, I do not think I would want meat in at that temp.