Author Topic: Firebricks Question  (Read 6460 times)

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Offline norma427

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Re: Firebricks Question
« Reply #25 on: May 28, 2010, 10:13:08 PM »
I have the tan/yellowish ones that are 4.5 x 9 x 1.25".  Each firebrick is 3 lbs 11.25 oz.

Tranman,

Yours sound almost exactly like me.  Wonder why yours is 1 1/4" thick and mine is 1 1/2" thick.  ::)  They must make them different thicknesses in different parts of country.

I will have to try different experiments with my BBQ grill and oven to see what happens.

Norma





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Re: Firebricks Question
« Reply #26 on: May 28, 2010, 10:47:34 PM »
Matt,

That is interesting to know that their are different grades of firebricks.  I just picked some up today.  Here is a picture of some of them. Are these the right kind?  If they aren't, I can take them back tomorrow.

Thanks,

Norma

They look exactly like the ones I have, and they don't insulate anything (someone mentioned they look like insulating bricks). They take the heat and radiate it very well.
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Offline norma427

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Re: Firebricks Question
« Reply #27 on: May 28, 2010, 11:00:51 PM »
They look exactly like the ones I have, and they don't insulate anything (someone mentioned they look like insulating bricks). They take the heat and radiate it very well.

Ronzo,

Thanks for letting me know they look like the ones you have and radiate heat very well.  This has been an interesting day, learning about firebricks.

Thanks for your info,  ;D

Norma

Offline carbon

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Re: Firebricks Question
« Reply #28 on: May 29, 2010, 01:34:05 PM »
I attached a photo of some white insulating bricks I'm using to create a thermal break in my oven project.  These bricks weigh only about a quarter of what the standard tan colored bricks weigh that I used in the dome.  Not only are these very light, they're brittle as well.

Offline norma427

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Re: Firebricks Question
« Reply #29 on: May 29, 2010, 01:38:27 PM »
I attached a photo of some white insulating bricks I'm using to create a thermal break in my oven project.  These bricks weigh only about a quarter of what the standard tan colored bricks weigh that I used in the dome.  Not only are these very light, they're brittle as well.

carbon,

Your oven project looks interesting.  :)  Since I don't much about insulating bricks, are they the same thing as firebricks or what should I ask for if I want to purchase some?

Thanks for your help,

Norma

Offline norma427

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Re: Firebricks Question
« Reply #30 on: June 13, 2010, 03:59:23 PM »
I was working on my BBQ grill oven today.  The firebricks are hard to cut.  In addition to the tools in this picture, I got many more tools out to try cutting the firebricks.  I did manage to get them all cut but one, and then it decided to have a shower.  If it stops raining, I will cut the last firebrick and test the oven tonight.  I did spit a few firebricks as can be seen in the pictures.

Norma

Offline Jackie Tran

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Re: Firebricks Question
« Reply #31 on: June 13, 2010, 04:18:08 PM »
Oven looks great.  Do you have a rotisserie burner to play with?  I gather not.  Without a rotisserie burner in the back or side & back air space for the heat to travel up, you may not get enough heat to brown the top.   I hope your bake goes well tonight.  Looking forward to your results. 


Norma, it looks like if you extend the side and back walls you can build the fire right inside and then push the coals to the side.  LOL.

I'm still tinkering with my MBE setup.  This pizza making is tricky business.

Tran
« Last Edit: June 13, 2010, 04:20:10 PM by Tranman »

Offline norma427

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Re: Firebricks Question
« Reply #32 on: June 13, 2010, 04:44:52 PM »
Tranman,

Thanks for saying the BBQ oven looks great.  I just finished cutting the last firebrick.  I donít have a rotisserie burner to play around with.  There is a gap in the back and sides of the firebricks.  There is also some vents in the back of my BBQ grill.  I do have some cherry wood bark and could try that to burn on the one side, but  just think I am going to try this out the way it is and see what happens.  I was thinking about cutting some steel sheet metal that was in the shed, but cutting these bricks were enough for me today. 

I agree that the pizza making business is tricky.  I will post the results, whether good or bad.  I am worried about loading the pie into the BBQ grill oven.  :-D

Best of luck in your MBE setup,  ;D

Norma

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Re: Firebricks Question
« Reply #33 on: June 13, 2010, 08:48:58 PM »
Wow Norma, cutting Firebricks with a hand saw?!?  :o Is the saw still intact?  ;D

Anyway, the setup looks pretty good. How big is the steel pan? 10 x 15? With a ceiling that doesn't cover the entire hearth, I don't think you'll have a choice but to turn the pie.  You might want to think about centering the pan on the two side supports rather than having it touch the back wall. If the hearth is 13.5" deep and the ceiling is 10", that's only 1.75" on the back and front, rather than a whopping 3.5" on the front.

The last time we talked, you were considering preheating the ceiling on it's own and then adding the hearth. Is that still your plan? If, so, I would blast the ceiling with all three burners for a while, seeing how hot you can get it.  Make sure you take the temp of the top bricks- that's the temp that really counts. The bricks are your heat storage. As you bake the pizza, the pan will draw heat from the bricks. If the top of the bricks is nice and hot (hopefully higher than 600), then they should have absorbed a decent quantity of heat and should stay hot for a while.


Offline Jackie Tran

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Re: Firebricks Question
« Reply #34 on: June 13, 2010, 09:07:30 PM »
Scott, if you preheat the ceiling first and then open the hood to build the hearth and walls, I would think once you close the hood again that the ceiling would start to lose heat to the other structures in the grill.  Wouldn't the heat strive to reach for equilibrium and readily give up it's heat to the non heated walls and floor.  How long do you think the ceiling would stay hotter than the floor heat?  What happens to pie #2 after a modest 5 min bake? Just wondering.  ???

Norma I'm getting hungry.  Where are those pies? :D

Offline norma427

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Re: Firebricks Question
« Reply #35 on: June 13, 2010, 09:31:41 PM »
scott123,

The steel pan is 12 Ĺ" by 17".  I only used two saws partially to see how they would fare.  I mostly used chisels, that I first scored the firebricks on both sides, kept using different chisels with a hammer, until the firebrick split to fit the hearth, sides and top steel pan.  My arms are aching now, from all that pounding. Even pounded my hand a couple of times. I didnít realize how hard firebricks are to cut.  I did ask the man where I purchased my firebricks how much they charge to cut them and he said 1.00 a brick.  I thought I would give a go myself. I also thought it was funny, when I told the owner what I was going to do with the firebricks and he said two other people had come in yesterday and were going to do the same thing with their BBQ grills. I said to him, they must be also looking at pizzamaking.com. He said it was unusual that people purchase them for their BBQ grills. It took longer than I thought it would to cut the firebricks. I could have also rented a water cutter from my local hardware store, but I like to do things by hand.

I didnít heat the top first today.  I just wanted to try this set-up to see what would happen.

Thanks for your advise.   :) I might be needing more as I try these different methods.

Norma

Tranman,

Here is the one and only pie I baked tonight.  It was getting dark and I had other things to do before I could get ready to bake this one and only pie.  ;D

Norma


I got to try making pizza for the first time tonight in the BBQ grill with the new set-up.  I let the BBQ grill with the firebricks heat for about 45 minutes.  I took the temperature of the hearth and top.  The temperature of the hearth was 610 degrees F and the temperature of the above firebricks on the pan was 565 degrees F.  The pizza baked a lot faster in this set-up.  I even let the pizza thicker. The pizza baked in 3 1/2 minutes. When I saw the bottom of the crust was starting to get dark, I took the pizza inside and put it under the broiler.  I just turned on the broiler when I got inside.  At least my kitchen didnít get hot. Even though the bottom crust looks dark, there was no burnt flavor. It just had a wonderful char flavor in my opinion. The pizza was 8 1/2"

Norma
« Last Edit: June 13, 2010, 09:45:25 PM by norma427 »

Offline norma427

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Re: Firebricks Question
« Reply #36 on: June 13, 2010, 09:33:01 PM »
more pictures

Norma

Offline norma427

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Re: Firebricks Question
« Reply #37 on: June 13, 2010, 09:34:00 PM »
more pictures

Norma

Offline norma427

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Re: Firebricks Question
« Reply #38 on: June 13, 2010, 09:36:07 PM »
last pictures

Thanks to everyone that helped me on this project and other posts on the forum about BBQ grill set-ups!   ;D  I never would have been able to do it without all your help,  :)

Norma

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Re: Firebricks Question
« Reply #39 on: June 13, 2010, 10:28:01 PM »
610 hearth 565 dome.... with a 45 minute preheat... interesting.

It's a little too much char for my tastes, but the puffiness/oven spring is impressive.

Do you have any charcoal?  I was thinking you might put a few coals on top of the firebrick ceiling. That might give you better ceiling heat with a quicker pre-heat. Charcoal should burn clean as well, as opposed to wood, which could gunk up the lid of the grill and eventually catch fire. Wood works in a WFO because it reaches hot enough temps to burn the tar away.

Btw, the next time you do this,  before the pizza goes in, could you take four temps?

Dome ext. (top of the firebricks)
Dome int. (middle of the steel pan)
Hearth int.
Hearth ext. (underneath the hearth, if possible)

I think that should give us a better picture of the thermodynamics.

Scott, if you preheat the ceiling first and then open the hood to build the hearth and walls, I would think once you close the hood again that the ceiling would start to lose heat to the other structures in the grill.  Wouldn't the heat strive to reach for equilibrium and readily give up it's heat to the non heated walls and floor.  How long do you think the ceiling would stay hotter than the floor heat?  What happens to pie #2 after a modest 5 min bake? Just wondering.  ???

Well, first of all, in my ceiling preheat scenario, the walls would already be place, so the hearth could be slide into place without having to handle hot bricks.

Secondly, firebrick's one slight flaw (low conductivity) is also one of it's strengths. It takes longer to heat up and doesn't transfer heat to the pizza as quickly (although, in this case, 610 firebrick transferred a surprisingly large amount of heat to Norma's pizza), BUT, it stays hot for a looooong time. If one were to heat firebrick to, say, 650, within a relatively closed system such as this, I would think it would stay pretty close to that for a while, especially with some heat (not a lot, but some) collecting in the head space with the lid closed. I couldn't guarantee that it would maintain that 650 indefinitely, but I think an hour or two (with the heat at full blast and the oven closed), would be no problem. Even if you turned off the gas completely but kept the lid closed, I would think the firebrick would cool very slowly. I'm totally guessing here, but I wouldn't be surprised if firebrick loses about 100 a degrees an hour in that scenario.

I heat my 1.25" soapstone to 550 and that's too hot to touch 3 hours later (with the door open) and soapstone is more conductive (loses heat quicker) than firebrick.

Offline norma427

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Re: Firebricks Question
« Reply #40 on: June 13, 2010, 10:51:52 PM »
scott123,

When I looked at the bottom crust, it did look like too much char for me too, but for some reason, it didnít have a burnt flavor.  I did have pizzas at my market stand that had to much char and they werenít even this dark.  I canít understand it, but it is something new to me. 

I donít have any charcoal at this time.  I have some kind of wood chips that are supposed to be used in a BBQ grill to give meats the smoky flavor, but have never opened the bag, so I donít know what to expect from them. 

I wanted to let the BBQ grill heat up longer to see how high I could get the temperature on the firebricks, but since it would soon be dark, I just made the pizza. 

I can take the temperatures you mentioned, but donít know how I would take the underneath the hearth temperature. 

I did take the temperature of the firebricks two hours after I turned off the BBQ grill with the lid open and the hearth temperature was 212 degrees F and the top firebricks were 168 degrees F. 

Thanks,

Norma

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Re: Firebricks Question
« Reply #41 on: June 13, 2010, 11:38:40 PM »
212 and 168... Lid open... Very interesting. I might have erred a little on the side of heat retention, but I think with the lid closed, we might be looking at a loss of 125 degrees per hour. That's not too terribly important, though.  The bottom line is that firebrick's poor conductivity causes it to hold it's heat for a while. Thanks for taking those temps.

Re; char.  I've noticed that when making Cajun roux, right before you burn it, there's a split second where it's black, but doesn't taste burnt. I think you hit that window.

For underneath the hearth, I don't want you to put yourself in a dangerous position, but if you can use a stick or something to tilt a brick up and shoot underneath it, that would be helpful.  It's not hugely important, though. I have a pretty strong feeling that the bottom of the brick will be considerably higher (700+) and it would be nice to confirm that, but it isn't essential. Basically, whatever temp you can achieve underneath- that's the temp you can get on the ceiling if the hearth were removed.


Offline norma427

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Re: Firebricks Question
« Reply #42 on: June 14, 2010, 12:19:43 AM »
scott123,

Next time I will let the lid closed and take the temperature over a two hour period, after the temperatures of the firebricks are up.

I just wonder what is the best temperature are to bake on the firebricks in my grill.  Guess I will find that out over time. 

As to the char, I was also surprised, I couldnít detect the burnt taste.  I really donít like a burnt taste to the crust, although some people do. 

I have some sheet metal and wonder if I cut it, bend it over on the edges on both sides of the exposed part of the grill grates and then have like a tunnel over the top of the firebricks if that would help to heat the top firebricks more.  Just trying to think of some ideas and donít really know how that would work.

I do have big barbeque turners and could lift one of the hearth stones to see what the bottom of the hearth temperature is.  That is what I used to rotate the pie today.  It would be interesting to see what that temperature is. 

Maybe if I have time this week, I will just take the bottom firebricks out and do a test on how hot the top firebricks get, before putting back the bottom firebricks to heat up.

Thanks,

Norma

Offline norma427

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Re: Firebricks Question
« Reply #43 on: June 14, 2010, 08:09:53 AM »
This morning, I decided to do a test of the BBQ grill set-up.  I moved the steel pan with bricks front more, so there is a gap in the back of the top, between the steel pan and back firebricks.  There is still a gap between the back firebricks and the back of the BBQ grill. I turned the BBQ grill on and will see how high the temperatures can get on the top and bottom firebricks.  I had commented earlier in this thread that my three burners were going crosswise.  That wasnít correct, I never looked, but thought they did.  Two of the burners run right under the ends of firebricks that are standing up.  The other middle burner is under the middle of the hearth. 

I took the piece of the galvanized steel out of the shed and have pounded the one end down. That was after I took this picture. Now I am still wondering if I cut the one end to fit and then pounded two ends over and put this on over the top position of the firebricks, if this will give them some more heat.  I will probably try that later in the week. 

I tried taking the bottom firebricks out to see how hard that would be in putting them back when the grill was hot and I donít think there is any way that I would be able to accomplish that while the grill is hot.  They are hard to slide into position, even when the grill is cold.

This is a picture of the BBQ chips I was commenting on.  They are supposed to be used in the grill for a smoky flavor. 

I also took a picture of how high the distance is from the hearth to the top of the steel pan with firebricks placed in the pan.  Another  picture of the side burner on the BBQ grill.  I donít know if there is someway to channel that heat into the opening on the side of the BBQ grill to also get the top firebricks hotter.  That opening is for a rotisserie.

Additional picture of front of BBQ grill. 

I will report back later on the temperatures of the firebricks.

Norma
« Last Edit: June 14, 2010, 08:13:09 AM by norma427 »

Offline norma427

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Re: Firebricks Question
« Reply #44 on: June 14, 2010, 08:11:58 AM »
last pictures

Norma

Offline norma427

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Re: Firebricks Question
« Reply #45 on: June 14, 2010, 10:10:36 AM »
In the last post I commented that my burners are crosswise.  I get crosswise and lengthwise mixed up, so to clarify this, I mean the burners are placed across the shortest distance.  I hope this clears up what I was trying to say.

I left the BBQ grill oven propane set-up on for 1 Ĺ hrs.  I took the temperature of the hearth and it was anywhere between 650-660 degree F, depending on where I aimed the infrared thermometer.
The top firebricks in the steel pan were anywhere between 520-539 degrees F.  I donít know since I moved the steel pan front, if that had something to do with the change in these temperatures.  Will have to do some more tests on that.  The bottom of the steel pan registered 632 degrees F.  The bottom temperature of the firebricks under the hearth measured 612, but that was the last temperature I took and the lid was open the whole time, while I was taking these temperatures, so there could be heat loss from keeping the lid open.  I just couldnít hold the lid up, hold the gun, and take pictures all at the same time, without the lid being open.  The heat was too intense for my hands.

I plan to take the temperatures again in one and two hour intervals, since the grill is turned off.

Norma

Offline norma427

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Re: Firebricks Question
« Reply #46 on: June 14, 2010, 11:59:20 AM »
These were the temperatures taken one and two hours after the BBQ grill was turned off.  After the first hour the hearth temperature was 324 degrees F and the top temperature with the firebricks in the pan was 301 degrees F. After two hours the hearth temperature was 187 degrees F and the top with the firebricks was 209 degrees F.  I really donít understand this, but know heat rises, but donít know if the firebricks that are in the steel pan kept their temperature higher in the 2nd hour because of the steel pan holding the firebricks or if the heat radiated from the bottom hearth.  These temperatures were all taken with the lid closed.

Pictured below are the two temperatures taken at hour two of the hearth and firebricks in the steel pan.

Norma


 

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