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fafrd

Ideal space between heat deflector and pizza stone?

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I did my first pizza cook with a 1-1/2" space between 13-3/4" heat deflector and 14" pizza stone and top of pizza stone positioned 1-1/4" above the felt line (7-3/4" below bottom surface of dome).

 

At that position, crusts cooked well at 800F but toppings lagged, so I'm planning to add a second, larger heat deflector and raise the pizza stone higher into the dome (I've read that 3-4" above felt line is apparently ideal).

 

In planning for this, I've also seen that 1-1/4" to 1-1/2" is apparently the spacing needed between deflector and stone but would appreciate to know what spacing others have had success with when raising the pizza stone higher into the dome (especially for 700-90F pizza cooking).  With a double-layer of heat deflectors and the pizza stone raised higher into the dome, I'm supposing the 1-1/4" to 1-1/2" spacing needed when the heat deflector is right above the firebox may no longer be as strictly required...

 

Especially for any experienced pizza-kamado chefs cooking with pizza stone raised 3-4" (or even higher) into the dome, I'd appreciate a summary of:

 

-spacing between heat deflector and pizza stone

-height between top of pizza stone and bottom of dome

-pizza cooking temperature

 

Thanks in advance!

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Hello Fafrd, 

 

I cook on this pizza set up and get results I am quite happy with

IMG_0409.thumb.jpeg.5df0300663c7bdd31101365318c1c427.jpeg

I use 14 " stones and the  kiln blocks I use as spacers give me a 1 5/8" air space. The top surface of my pizza stone when the set up in in my Egg is about 1/4 inch above the felt. Actually from my perspective, as long as the top surface of your pizza stone is anywhere above the felt It just makes it easier to get your peal under a pie. 700 to 900 degrees is pretty hot. Most dough recipes are designed to be used at a specific temperature. The dough recipe I use is Ken Forkish's 24 to 48 hour pizza and is designed for around 500 to 550 degrees, although I usually cook at about 600 and like the results that temp gives. I am guessing your crust cooked quicker than the toppings because of the high temp you cooked your pies at. Remember in a kamado the heat comes from beneath the stone whereas in a pizza oven the heat comes from above as the fire curves with the ovens dome. My pizza cooks improved a lot when I started using actual stone temp rather than just the temp off my dome thermometer. When I started using a laser temp robe to measure my stone temp, I instantly started getting better results. Have fun. Pizza for me is a seemingly never ending quest, as I have been messing with both my set up and my dough recipe for quite some time. 

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8 hours ago, keeperovdeflame said:

Hello Fafrd, 

 

I cook on this pizza set up and get results I am quite happy with

IMG_0409.thumb.jpeg.5df0300663c7bdd31101365318c1c427.jpeg

I use 14 " stones and the  kiln blocks I use as spacers give me a 1 5/8" air space. The top surface of my pizza stone when the set up in in my Egg is about 1/4 inch above the felt. Actually from my perspective, as long as the top surface of your pizza stone is anywhere above the felt It just makes it easier to get your peal under a pie. 700 to 900 degrees is pretty hot. Most dough recipes are designed to be used at a specific temperature. The dough recipe I use is Ken Forkish's 24 to 48 hour pizza and is designed for around 500 to 550 degrees, although I usually cook at about 600 and like the results that temp gives. I am guessing your crust cooked quicker than the toppings because of the high temp you cooked your pies at. Remember in a kamado the heat comes from beneath the stone whereas in a pizza oven the heat comes from above as the fire curves with the ovens dome. My pizza cooks improved a lot when I started using actual stone temp rather than just the temp off my dome thermometer. When I started using a laser temp robe to measure my stone temp, I instantly started getting better results. Have fun. Pizza for me is a seemingly never ending quest, as I have been messing with both my set up and my dough recipe for quite some time. 

 

Thanks for the response.  Is that metal grating under your head deflector a BGE accessory or aftermarket?

 

I used an IR thermometer to monitor all sorts of temps including center of pizza stone, outside of dome, outside of aluminum vent, and top inside of dome (less often due to heat loss).

 

So the center of my pizza stone was at 900F but I didn't think to also check temp closer to the outside edge.  Because my pizza stone ended up being 15-1/2" rather than 15" and my heat deflector was actually 14-1/2" rather than 14", I had a ~1/2" overhang and that probably means the outer edge of the pizza stone was getting sone direct heat and was likely higger than 900F.

 

Temp of the dome thermometer never got higher than 800F, so the crust was probably cooking closer to 1000F than 900F while the toppings were only cooking at 800F.

 

Your 1-5/8" space is close to the classic space most everyone uses, so I'm now thinking I'll also stick around the same ~1-1/2" spacing I used for my first cook.

 

At higher temps of 800-900F, others are telling me they have better luck pushing the pizza stone much higher into the dome than the 1-1/4" above felt line I used last time (or the 1/4" that you use).

 

One owner of the same LG24 grill that I have cooks at 900F with his puzza stone only 2" below the inside ceiling of the dome!  This is the reason I asked about your metal grating - to find ways to get higher into the dome.

 

Your grating looks much more solidly-built than the double grating that came with my Kamado.  I can use it to get very high into the dome but I'm nit wild about using my thin cooking grates over direct heat needed to reach 900F: 

 

 

 

63A6A933-A5C0-4CAA-9D70-38872C25B2C6.jpeg

 

A secondary benefit or getting the heat deflector well above the felt line at high temps is less wear on the gasket.  This second pic shows how the wide legs of my heat deflector protected my brand-new 1000F grey gasket and prevented the charring that effected the inside edge of the gasket everywhere else:

 

 

677B903E-DDA5-4E90-BA8E-8EB19C11C22F.jpeg

 

I was really happy about how easy it was to manipulate pizza on, off, and rotating it with my pizza stone only 1-1/4" above the felt line and I'm a bit nervous about it being more unweildy/complicated and losing more heat when the pizza stone is much higher into the dome and the dome needs to be opened completely to manipulate pizza.  So I may just try raising the pizza stone to 3-4" with ceramic spacers to start like this:

 

 

 

 

31519322-153E-4343-B673-ADFFBF80537C.jpeg

 

This is using my brand-spanning new 16-1/4” pizza stone as a second heat deflector to protect the 15-1/2” pizza stone and I can position anywhere from 2” into the dome to 5” into the dome using various-sized ceramic spacers between the stock heat deflector and the secondary 16-1/4” heat deflector.

 

All-ceramic and no metal (which I slightly prefer) but >900F hot air directly off of the burning lump will still be deflected onto the felt gasket so it will likely continue to char from 900F pizza cooks.

 

Any thoughts appreciated (especially from anyone else cooking Nepolitan with 60% hydration dough at 800-900F).

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34 minutes ago, fbov said:

Well, here's my set-up; stone on extension rack, deflectors on accessory rack.1316095694_PizzaConfiguration.thumb.jpg.ded655ba5adfb1d545675cd2d855f4f1.jpg

 

Nice!  Did that extension rack come with you Kamado or is it aftermarket?  It looks beefier than the dual-grate system that came with my LG24.  Is your pizza stone ending up about 6" above felt line?  What temps are you cooking pizza at?  Others have told me that having the pizza stone spaced more than 1-1/2" above the heat deflector is the same as having no deflector at all, but that is not your experience?  If you yanked out the deflector the pizza stone would get too hot from direct heat?  What is the space you have between too of pizza stone and inside ceiling of dome?

 

I guess one option to set up a rig similar to yours would be to pick up one of these 'Adjustable Racks' from the Ceramic Grill Store: https://ceramicgrillstore.com/collections/pit-boss-24-kamado-grill-costco/products/pit-boss-24-adjustable-rig-combo

 

It appears to be made out of beefier stainless like your extension rack, sits 6" above the firebowl / 3-1/4" above the felt-line.  From there I could place my 16" heat shield, 1-1/2" spacers, and my pizza stone to get 6" above felt-line...

 

Thanks for your post - examples of Kamado Pizza chefs who are defying conventional wisdom and having success with larger spacing between heat deflector and pizza stone is exactly why I started the thread :).

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7 hours ago, fafrd said:

Did that extension rack come with you Kamado or is it aftermarket? ... What temps are you cooking pizza at?  

Stock KJ extension rack. It's in backwards; the flat side should be toward the front, to provide temp probe clearance.  

 

I like to run it up to 850-900 F, then cook at more like 800-850. Last weekend, it peaked at 770 F, so I cooked lower, for more time. Every cook is unique in some respect. This one was "wet." Humidity's up, so 67% turned out more like 75% hydration. Still crisp, chewy and as interesting as the chef made it. Broccoli, bacon and cheddar worked well dry. 

 

Have fun,

Frank

 

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16 minutes ago, fbov said:

Stock KJ extension rack. It's in backwards; the flat side should be toward the front, to provide temp probe clearance.  

 

I like to run it up to 850-900 F, then cook at more like 800-850. Last weekend, it peaked at 770 F, so I cooked lower, for more time. Every cook is unique in some respect. This one was "wet." Humidity's up, so 67% turned out more like 75% hydration. Still crisp, chewy and as interesting as the chef made it. Broccoli, bacon and cheddar worked well dry. 

 

Have fun,

Frank

 

 

Nice!  I spoke to the guys at the Ceramic Grill Store and I think I am going to get their 'Adjustable Rack' to allow me to achieve in my LG24 what you are doing with your KJ Extension Rack.

 

For this weekend, I'm juat going to try using the stock LG24 double-grate to come as close as I can and after talking to Tom at CGS, once the pizza stone is high into the dome, there is no advantage to using any heat deflector at all and in fact a heat deflector can possibly cause uneven pizza stone temps (hotter towards the edges).

 

So based on that input, I've decided this is the 800-900F pizza cooking configuration I am going to try this weekend:

image.jpeg

 

The triple-stack effectively gives me a 1-7/8" thick pizza stone positioned 4-1/2" above the felt-line, 8" above the top of the firebowl, and 4-3/8" below the inside ceiling of the dome.

 

We'll see how it works!

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If you do this, put some sort of spacers between the ceramic disks. You need air circulation to even out temps and allow the stones to heat uniformly. 

Frank

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13 hours ago, fbov said:

If you do this, put some sort of spacers between the ceramic disks. You need air circulation to even out temps and allow the stones to heat uniformly. 

Frank

Turns out that is a very deep question, Frank.

 

Using a heat deflector and 1-1/2" spacers to the pizza stone is what I did on my first pizza cook.

 

The top surface of the pizza stone was 7/8" above the felt line and the result was good, but crust a bit more charred than we'd like and toppings that were never done (had to hold the pizza on the peel close to the dome for another 1-2 minutes to get the top properly done).

 

So now I want to try moving the pizza stone up much higher into the dome for our second attempt this weekend.

 

My original plan was to use the 1-1/2" spacers between heat deflector and pizza stone, as you suggest, but after seeing several Kamado owners here post that they cook pizza with the stone a mere 2-1/2" below the done and without any heat deflector at all, and also after speaking with Tom at CGS, I've decided to try the high-into-the-dome-direct-heat method.

 

Tom's argument is that if the hot air is coming straight up off of the lump and hitting the pizza stone high in the dome directly, you want that heat source to be unimpeded to maximize uniformity.  This also means using your vents to control the burn so that the hot air hitting the stone is ~900F and not higher.

 

So I'm going to give it a try with direct heat (and a very thick heat-mass / pizza stone which is effectively 1-7/8" thick).  Last time I'm pretty sure the edges of my pizza stone were closer to 1000F than 900F even though the center measured 900F because the pizza stone extended 1/2" beyond the heat deflector and the excessive charring was primarily near the outside edges (didn't occur to me to measure pizza stone temps near the edge).

 

This time, I'll measure puzza stone temps both at center and near the edge and my expectation is that if there is any hot spot, it will be at the center rather than near the edge.

 

We're planning to cook 12 pizzas this way and I'll let you know how it turns out.  Have you ever tried moving you heat deflector stone directly up under your pizza stone (no heat deflector and a pizza stone which is effectively twice as thick)?

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11 hours ago, fafrd said:

Turns out that is a very deep question, Frank.

Not really. I expect the middle stone of this sandwich to crack.  

 

11 hours ago, fafrd said:

Tom's argument is that if the hot air is coming straight up off of the lump and hitting the pizza stone high in the dome directly, you want that heat source to be unimpeded to maximize uniformity.

Tom's argument is missing something. Radiation. 

 

A heat deflector blocks a huge amount of IR radiation coming from the coals. Remember that the wood in a burning fire is over 1000F, even when cooking low-n-slow, and more like 1500-2000F if it gets a strong flow of fresh air. The gas coming off it mixes and cools quickly, but it's weak compared with IR radiation. Anything that's line-of-sight to the fire will be a lot hotter than the air around it. 

 

So try Tom's approach, but with your eyes open. 

 

have fun,

Frank

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12 hours ago, fbov said:

Not really. I expect the middle stone of this sandwich to crack.  

 

Tom's argument is missing something. Radiation. 

 

A heat deflector blocks a huge amount of IR radiation coming from the coals. Remember that the wood in a burning fire is over 1000F, even when cooking low-n-slow, and more like 1500-2000F if it gets a strong flow of fresh air. The gas coming off it mixes and cools quickly, but it's weak compared with IR radiation. Anything that's line-of-sight to the fire will be a lot hotter than the air around it. 

 

So try Tom's approach, but with your eyes open. 

 

have fun,

Frank

 

Thanks for the explanation.  I independently came to the conclusion that I want to keep the 1-1/2" spacer between 15" pizza stone and 16" heat deflector resting on the LG24 Place Setter.

 

Yesterday I did a little trial-run at lower temps and there was a greater heat differential between the pizza stone and the inside of the dime than I would like.  

 

Whether due to hot air coming off the lump or IR as you suspect, it is clear to me now that the heat deflector is the hottest part of ceramic within the upper half pf the Kamado and unless you want  the pizza stone significantly hotter than the dome, insulating the pizza stone from the direct heat of the heat deflector with spacers is important.

 

Between the radiant heat emitting from the top surface of the heat deflector and the lower level of radient heat emitting from the inside surface of the dome, I'm hoping spacers which get the pizza stone closer to midway in that heat-deflector-to-dome space will allow the pizza stone to settle at nearer the mid-point between those two temperature extremes (of deflector and dome).

 

What do you reckon is the gap you have between your pizza stone and the inside cieling of your dome?  With 1-1/2" spacers my pizza stone will be 2-7/8" below the center of the dome, 2-3/8" below the outside of the dome over the pizza crust, and 1-7/8" below the tip of the thermometer.

 

Here’s a picture of the final configuration I’m going with for this evening’s second attempt at Neopolitan pizza:

 

 

5A6DAA00-86C3-42DB-AA89-1796FAFB9838.jpeg

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12 hours ago, fbov said:

How'd it go?

 

Much happier with cooking far into the dome and the pizza came out very good.

 

Here are an example pic:

 

 

 

6143545F-60A0-4A95-8D5A-3BDF16DEC8BE.jpeg

 

One of the huge huge wins of cooking with a few inches of the vent is that you can watch the toppings cook and literally watch the leoparding on the edge of the crust form.  This pizza was actually cooked at a bit lower temp but has better charting on the crust because I’d figured out how to watch the crust to decide when the pizza was ‘done’

 

5C37316D-EF68-401A-B912-4301A529FC43.thumb.jpeg.3646cc4655eb04d1f8f237461ab07cbc.jpeg

 

The 1-1/2” spacers between heat deflector and pizza stone worked like a charm.  No heat gradient at all on pizza stone - edges identical temp to center.  Compared to the trial run I did at lower temps yesterday where there was a ~5% gradient in the pizza stone with center being hotter than edges with no spacers.  So I’m afraid Tom at CGS was incorrect and heat uniformity of the pizza stone is better using 1-1/2” spacers even when the pizza stone is raised far into the dome.

 

No undercooked tops, no overcharred bottoms, uniform/equal cook of top and bottom, ability to visually cook until desired leoparding develops on top crust - this would have been an A+ cook except for one thing:

 

Temps peaked at 750F and slowly dropped from there.  The first pizza you see above was cooked at over 700F and the second pizza (with better leoparding on the crust) was cooked at just over 600F.  The bottom crusts had no charring and while our guests all thought the pizza was excellent and it all got devoured, the 4 of us that cooked the over-charred pizza at 900F the weekend before all thought that was better pizza and missed that charred bottom crust flavor.

 

I’m pretty sure the primary reason this cook peaked at 750F and then started to decline while last weekends cook hit 900F and held there for over an hour was that I was unable to load as much fresh lump into the cooker.

 

With the metal grating resting right on the bowl yesterday versus the plate setter whose legs lifted the barrier a few inches above the top of the bowl last weekend, there was less volume available.  In addition, I thought I’d be smart and start the burn using the 1/4 bowl of leftover lump from last weekends cook with idea that it would burn down as the Kamado started heating up and I would be able to fill the bowl with fresh lump when the pizza stone reached 300F.

 

Moving the pizza stone out of the way at 300F to fill worked like a charm but the old lump was still occupying slot of volume, so I was only able to put about 1/2 the volume of fresh lump as I used last weekend.

 

Now that I know the ‘cook high in the dome with 1-1/2” spacers’ method works well but that the LG24’s stock grating is I’ll-suited to that configuration, I’m going to go ahead and get an Adjustable Rig from CGS.

 

Next weekend, I’ll fill the bowl with 100% fresh lump and go after the holy-grail of achieving a uniform Neopolitan cook in the 800-900F range with the bottom-crust charring we’ve come to prefer (pic from last weekend’s cook):

3F0EB9BD-FA4B-4CB2-A96E-3F6F01990329.jpeg

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On 8/11/2019 at 1:05 PM, fafrd said:

I’m pretty sure the primary reason this cook peaked at 750F and then started to decline while last weekends cook hit 900F and held there for over an hour was that I was unable to load as much fresh lump into the cooker.

 

... start the burn using the 1/4 bowl of leftover lump from last weekends cook ...

Heat comes from a lot of fuel getting a lot of air. 

 

I love using leftover charcoal, because the cheap stuff (RO) does light quick and disappear. The denser charcoals, and the larger lump coals do not do this. They become hard to light, for lack of surface area, and have given up a lot of energy. Plus, used fuel has little pieces that clog air vents. 

 

So, use new fuel, and put some big pieces on the bottom, so the vent holes aren't clogged by little stuff. Break apart any lumps bigger than your fist so they light easily. 

 

And if this kind of cook is is what you like, get an ash basket. It does take up some fuel room, but it lets air in much better, and makes it easy to dump spent fuel. I guess I ought to plan pizza again soon, to see if I can put my money where my mouth is. After all, my last cook only made 770F. 

 

Have fun,

Frank

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1 hour ago, fbov said:

Heat comes from a lot of fuel getting a lot of air. 

 

I love using leftover charcoal, because the cheap stuff (RO) does light quick and disappear. The denser charcoals, and the larger lump coals do not do this. They become hard to light, for lack of surface area, and have given up a lot of energy. Plus, used fuel has little pieces that clog air vents. 

 

So, use new fuel, and put some big pieces on the bottom, so the vent holes aren't clogged by little stuff. Break apart any lumps bigger than your fist so they light easily. 

 

And if this kind of cook is is what you like, get an ash basket. It does take up some fuel room, but it lets air in much better, and makes it easy to dump spent fuel. I guess I ought to plan pizza again soon, to see if I can put my money where my mouth is. After all, my last cook only made 770F. 

 

Have fun,

Frank

 

Yeah, I've been putting 2-3 softball+ -sized chunks of fresh lump right on the fire grate ay the lowest level of the firebowl, the putting layers of smaller and smaller lump up from there, with the smallest pieces on top.

 

I'm pretty happy with the ventilation I'm getting and how well the lump is burnibg and getting consumed.

 

The mai  issue with this last coom is that the old lump cotinued to consume volume past the point I thought it would have turned to ash and as a result, I was not able to load the volume of fresh lump I planned for.

 

When I finally opened the vents to get temps up to 900F, temps started to stall near the 750F and when I peeked in, it was clear all pf the fresh lump was largely consumed and I was not goi g to heat up any higher without adding additional fuel (which I am reluctant to do at 750F).

 

So I think the main lesson for me is: save old lump for burgers and direct grilling (especially if new fuel can be added).  And stick to 100% fresh (high-quality) lump for 800-900F pizza cooks...

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