Go Back   Forno Bravo Forum: The Wood-Fired Oven Community > Oven Management > Heat Management

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-10-2011, 10:01 PM
Tenorio74's Avatar
Laborer
 
Join Date: Jan 2011
Location: Peru
Posts: 78
Default Floor temperature drop-off rate vs. floor-brick saturation

Hi all,

It's been a couple of weeks since I fired, but last night I finally managed to light her up and do some pizza (only 8 to be precise).

Starting cold, I had my dome (51 in. diameter) clear in about 1:30-1:45 (didn't time it ), and my floor at 850 when I moved my fire to the side **mental note: I have to practice removing the ashes and unburnt coals from the start-up fire sooner (maybe at 1 hr), which were covering the whole center of the oven floor like a blanket.**

The floor got hot anyway, but I am wondering if there wasn't a true heat saturation throughout the floor bricks. I guess this is the main question....

After cooking my first four pizzas (leisurely, 'cause I was eating too ), the drop-off in temperature was quite noticable. If I wanted the underside done properly, the cheese on top was burnt "pizza hut" style, which isn't my thing because I'm going for almost neapolitan.

If I keep a nice big flame licking the middle of the dome from the side, I figure I can control the drop-off. But doing that, then the dome is too hot which will turn out 1:30-1:45 pies, bottom soggy / top nice.

Any comments from anyone futher down the road? I eventually will have to keep the oven hot in 4 hr shifts, producing, hopefully, many many pizzas in that time for paying customers.

How do we get the floor hotter that the dome?!? That would be the bomb.... Then I could just lift it up to get a proper finish. The pics are the floor being replaced (2" ceramic fiber board / 2.5" firebrick) after the oven was done. Nasty job, I don't recommend it especially with no help and a low dome!!
Attached Thumbnails
Floor temperature drop-off rate vs. floor-brick saturation-replacing-floor-1.jpg   Floor temperature drop-off rate vs. floor-brick saturation-replacing-floor-2.jpg  
Reply With Quote
  #2  
Old 02-11-2011, 04:07 AM
Il Pizzaiolo
 
Join Date: Nov 2006
Location: San Antonio
Posts: 1,719
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Ash is very insulating. Assuming your oven is dry and properly insulated, the hearth was not heat saturated. It appears your firing practice is building up too much ash on the floor too early in the process. I would suggest clearing the oven of ash after 45 minutes or so (push the bigger pieces to the side and simply clear the ash then rearrange the big pieces) and add more wood. Your problem is not too unusual and spreading coals back over the hearth for five minutes or so is a normal cure --- but your description suggests your hearth is seriously cold. What temp does it drop to? (And if you don't have an IR thermometer buy one!)

When you fire and keep the oven fired daily the problem should go away. And there is NO way to make the hearth hotter than the ceiling in a proper oven for heat rises. The hearth will always be 50 to 75 degrees F cooler than the dome. Besides, you don't want it hotter!
Reply With Quote
  #3  
Old 02-11-2011, 04:20 PM
Tenorio74's Avatar
Laborer
 
Join Date: Jan 2011
Location: Peru
Posts: 78
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Thanks Tex,

I just had a discussion with my business partner on the logistics of shovelling out ash twice a day, and what to do with it in the restaurant environment....

So you finish clearing the dome with the fire on the side? Your central floor still comes up to temp? At 45 mins I guess I'm about 50% clear.... Once I finish clearing the dome the soldier course clears pretty fast.

I need to make proper oven tools.... There aren't any to be bought down here... I'm using fireplace stuff. Help me out, I would need a log-handle:
shovel
rake (without teeth / flat)
rake (with teeth, to pull coals without pulling the ash?? Does this damage the floor?)
metal ash bin
oh a decent log mover or something
As soon as I uncover the ash/unburnt coals on the floor, the light up thanks to the fresh air.... If I take them out I guess they'll be red hot. Do you douse them or something? When you say bigger pieces, do you take out the little red coals aslo?

Man I hate the learning curve...
Reply With Quote
  #4  
Old 02-12-2011, 06:47 AM
dmun's Avatar
Moderator
 
Join Date: Jul 2005
Location: New Jersey USA
Posts: 4,216
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

In a home oven, the amount of wood needed to fire the oven burns down to a negligible amount of wood ash. Most often this is shoveled out later when it's cold. In a commercial environment there must be a way to separate ash from fire, but I don't know what it is.

When I need to shovel out a live fire for retained heat baking, I put the coals into a metal trash can. This is outside, so it doesn't matter if it stinks a little. You might want some kind of sealing container if you are working inside.
__________________
My geodesic oven project:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
,
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #5  
Old 02-12-2011, 08:21 AM
Il Pizzaiolo
 
Join Date: Nov 2006
Location: San Antonio
Posts: 1,719
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Hi Tenorio...

It sounds like you may not be fully charging your oven. And...why is your soldier course not clearing with the fire inside??? Sounds like you need to go longer - if 45 minutes as I think you indicate, perhaps 1 hr 15. Your oven is not really "ready" when it clears. The refractory is still absorbing a lot of heat. The temp at the surface is ONLY about 750 and that is on the dome. The hearth will almost always be cooler. Go longer. Get the oven significantly hotter than you want it. I am going to guess you are burning soft wood and that is contributing to your ash issue. Rereading your origninal post you are definitely NOT getting your oven hot enough.

You need to see an oven in a good operation. With a 51 inch oven you need a good size fire on one side of the oven. You can have a ton of ash on that side and it won't matter. But the side you are cooking on needs to be HOT! 750 to 850 on the hearth depending on flour, hydration, etc. IF you don't have an infrared thermometer the easiest way to guess the temp is throw some flour or semolina on the hearth. If the flour turns black in about 3 seconds (count one thousand one, one thousand two, etc.) the hearth is about the right temp . Your soggy pies are being cooked on a hearth that might NEVER turn the flour black. And...if the flour should turn black in one second it is way too hot and will burn the bottom of the pies. If the time gets much longer than 3 seconds, rake the coals out across the hearth to recharge the cooking area. Then push them back onto the fire side and clean the cooking surface and wait for it to cool some and start testing the temp again. Once you get to the soggy pie stage it may take half an hour to get the surface hot enough.

Good luck!
Jay
Reply With Quote
  #6  
Old 02-12-2011, 12:15 PM
Tenorio74's Avatar
Laborer
 
Join Date: Jan 2011
Location: Peru
Posts: 78
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Thanks Jay!

Just to clarify.... I do have an IR thermometer. Surface temp was about 825 when I moved the fire to the side. Flour blackened in 1 second.

I let it drop to about 800 and did my pie in about 1:30. But the top got way overdone, bubbling cheese (for some this is ok, I like my cheese just melted).

My dome clears fine, starts out in the middle then expands out. What I meant is that the soldier course is the last to clear, usually fast once the whole top is white.

I'd love to see an oven in full operation, but this type of pizzería does not exist down here, and I can't travel anywhere now to see. So I guess it'll just be trial and error.

OK, floor bricks aren't saturated enough.... I have a big floor. So I'll go longer once I clear the dome. My question is, do you finish clearing the dome with your center (initial) fire, or finish it once you've moved the fire to the side??

Thanks for your insight,
Tenorio
Reply With Quote
  #7  
Old 02-12-2011, 03:05 PM
lwood's Avatar
Master Builder
 
Join Date: Jul 2009
Location: philippines
Posts: 642
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Ten, I don't think you are saturated. Once the dome clears, the fire-brick is only 800F on the interior surface. The entire fire-brick needs to get to that temp. Your 51" floor will take longer to get totally saturated. I have a 60" oven and I take at least an extra hour, after clearing, to get it saturated.
__________________
Our Facebook Page:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #8  
Old 02-12-2011, 04:18 PM
Tenorio74's Avatar
Laborer
 
Join Date: Jan 2011
Location: Peru
Posts: 78
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Wow, an extra hour... Thanks for that Lwood. I'll keep it an hour more on the side - do you finish clearing your dome with the fire in the middle or off to the side?

Your 60" must consume A LOT of wood (jajaja that's the your nickname expanded - Lot of WOOD).... I think I underestimated my overhead wood costs...
Reply With Quote
  #9  
Old 02-13-2011, 05:03 AM
lwood's Avatar
Master Builder
 
Join Date: Jul 2009
Location: philippines
Posts: 642
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Not really that much wood....never thought of it that way...but the Lots-a-Wood handle would be kinda cool... The Lwood comes from the old Blues Brothers days. L is my middle initial and Wood is my last name. I can get my oven saturated with about 2 cubic ft of wood... and I'm not using anything special. Just what I find around the property. But I am finding that is not sustainable for a commercial application. I am going to install a gas burner.

I can get to 600F in your standard 45 minutes, but that's just barely getting warmed up. You need to keep a good hot fire going for another hour to be sure. Your 51" should take less time but you will see a big difference in the heat retention time if your get completely saturated.
__________________
Our Facebook Page:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Reply With Quote
  #10  
Old 02-13-2011, 08:22 AM
Tenorio74's Avatar
Laborer
 
Join Date: Jan 2011
Location: Peru
Posts: 78
Default Re: Floor temperature drop-off rate vs. floor-brick saturation

Next pizza trials I'm gonna fire 1:30 in the middle and 1:00hr more on the side..... We'll see how that helps out. I'm also gonna drop a percent or two on the water content in my dough, to combat the sogginess (and it'll help the pizza tossing!). That should be this week, I'll let you guys know.

Thanks a bunch,
Tenorio
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 09:27 AM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
© 2006/10 Forno Bravo, LLC