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-   -   What is wrong?? (http://www.fornobravo.com/forum/f16/what-wrong-19925.html)

Filthymutt 09-12-2013 05:52 AM

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:confused:

stonecutter 09-12-2013 06:30 AM

Re: What is wrong??
 
Quote:

Originally Posted by Filthymutt (Post 161674)
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:confused:

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 09-12-2013 06:36 AM

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 09-12-2013 07:54 AM

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 09-12-2013 10:12 AM

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 09-12-2013 05:42 PM

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 :rolleyes:

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

mrchipster 09-12-2013 06:48 PM

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 09-12-2013 07:35 PM

Re: What is wrong??
 
Quote:

Originally Posted by Filthymutt (Post 161674)

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). :eek:

brickie in oz 09-13-2013 12:27 AM

Re: What is wrong??
 
Quote:

Originally Posted by Les (Post 161718)
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). :eek:

Thats the way......:D

Sounds like the oven is still wet.

Filthymutt 09-21-2013 10:39 AM

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


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