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Author Topic: My overclocked Roccbox oven  (Read 6564 times)

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Offline overdo-everything

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My overclocked Roccbox oven
« on: May 02, 2018, 03:22:54 AM »
I was satisfied with the temperature I could reach with my stock Roccbox, but I wanted to decrease the warmup time (for my oven, about one hour in its stock configuration), and experiment with bake temperatures at the upper end of what might work. I speculate that the most elegant way to modify the oven would be to replace or modify parts in the burner assembly to make it burn more fuel at the standard propane pressure of 11" W.C. (about 1/2 psi). But the Roccbox burner assembly is a custom item, and the enclosure is riveted shut. So I left the burner alone and replaced the regulator with one that would allow me to use higher than standard pressure. Details below.

I've experimented with propane pressures throughout the range 1/2 psi to 2 psi. I currently run at 2 psi, although after you see what I'm sharing here, you might reasonably believe that 2 psi is a bit higher than ideal for this oven. At 2 psi, the oven is definitely ready to bake pizza after 15 minutes of warmup, although it is not fully heat soaked and at maximum temperature until a while later. With this configuration, I can achieve a 50-second bake. These have been my best pizzas -- at about the 50 second bake time. Higher temperatures, supporting even shorter bakes, are possible, but I personally have difficulty getting good results when managing an even more compressed time frame.

The Roccbox burner design creates a long, yellow flame, indicative of incomplete combustion, and in a sense, incorrect fuel-air mixture. But this seems to be by design. I do not understand why this is the correct design, but they all work this way, and it does work. Running at pressures between 1/2 psi and 2 psi, the stock burner maintains this flame profile.

At 2 psi, the oven delivers more than a rolling flame over the floor. The flame doesn't fit inside the oven. It just pours out the front. I've included photos of that, and a time vs. temperature graph. The graph ends at the 35 minute mark because I can't measure the temperature beyond that time. At 40 minutes, the stone surface temperature was too high for my infrared thermometer to read it, and the Roccbox's built-in thermometer, reading under the stone, registered slightly over its maximum indication of 500 C. By 60 minutes, the Roccbox's dial thermometer had wrapped around, and pointed closer to 0 than to 500.

I let it get this hot only for the fun of the photograph. In practice, I run the oven full blast until the stone top surface temperature reaches about 500 C, measured by IR, and then I turn the Roccbox's flame control down to its lowest setting. At 2 psi, the visual appearance of the flame at the oven's lowest setting is similar to the flame at the stock Roccbox's maximum setting. To cook a pizza, I turn the flame back up to maximum and then immediately launch the pie. This seems to be the key to getting hot bakes without burning the bottom. By letting the oven idle on low, and then blasting the fire at the time I launch the pizza, I get the top cooked in time before the bottom burns. I will return to the subject of heat balance momentarily.

I want to share more about the selection of a regulator. Most regulators that are adjustable are high-pressure regulators. The lowest-range regulator that I could find that is built in the style typical of regulators for outdoor cooking equipment is 0-5 psi. I have not tried that regulator. It might work just fine. But I would guess that, in supporting such a wide range, the degree of control it would offer in the lower end of its range -- in the region just above the standard pressure of 1/2 psi -- would be unsatisfying.

I wanted a regulator that was nominally 1/2 psi, or 1 psi, or 2 psi, with a small but precise range for adjustment around the nominal setting. I found what I was looking for in the format of regulators intended for whole houses, or very large appliances. These are gross overkill in flow capability for the Roccbox, which is a low-flow device. But they provide fine resolution of adjustment in the range of interest, and they are exceptionally stable (they stay at the pressure you set). The regulator I settled on is the Emerson-Fisher R232E-BBH. I created a shopping list at Amazon ( https://www.amazon.com/hz/wishlist/ls/3R5JKLH21Z1O2), to help anyone who might want to put together the parts to build this setup. I used a quick-release fitting on the oven-side of the hose, so that I can easily move the oven about without the awkwardness of dragging a hose and regulator along.

Now let's return to the subject of heat balance. The Roccbox is supplied with a cordierite baking stone. From reading this forum, I've learned that cordierite is not the ideal baking surface at Neapolitan temperatures, owing to its high thermal conductivity. I was hoping that I could improve my heat balance by replacing the stock stone with one of lower thermal conductivity. I purchased a FibraMent stone from www.bakingstone.com, custom cut to the size needed for the Roccbox (13 13/16" X 13 1/16" X 3/4"). To swap stones, I had to drill out the rivets that hold the front of the oven on. With the rivets gone, the front face of the oven easily pops off. The new stone easily slides in, and the front piece can be replaced. I have not used any mechanical fasteners to hold the front piece of the oven on. The friction fit seems entirely sufficient.

FibraMent is reported to have a significantly lower thermal conductivity than cordierite. I was hoping for a dramatic improvement in heat balance, in the direction of less heat entering the bottom of the pizza. In actuality, I think I can tell the difference. I think the FibraMent stone is better. But it's not a huge difference. Not like what people report going from cordierite to biscotto saputo.

Offline HansB

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Re: My overclocked Roccbox oven
« Reply #1 on: May 02, 2018, 04:07:59 AM »
Have you found a source for Biscotto Saputo tile to fit the RB?
Hans

Offline barryvabeach

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Re: My overclocked Roccbox oven
« Reply #2 on: May 02, 2018, 07:14:14 AM »
Thanks for the detailed writeup.  I don't have a Roccobox, but I am sure other owners will find your experiments enlightening. Saputo would be ideal, though it is hard to find.

Offline TXCraig1

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Re: My overclocked Roccbox oven
« Reply #3 on: May 02, 2018, 08:30:43 AM »
That's very cool, but for what you ended up spending, why not get a Pizza Party oven instead?

I doubt that roccbox floor is cordierite. I bet it's some sort of firebrick. Cordierite is WAY too conductive for Neapolitan which is why people see such a big change when moving to other deck materials.

Approximate thermal conductivities:

Cordierite  3.0 W/mK
Firebrick  1.0 - 1.1
Light duty fire brick  0.7-0.8
Fibrament  0.7
Biscotto Saputo or Sorrento  0.3-0.5*

*not published data. My estimate from having cooked on all of these.
« Last Edit: May 02, 2018, 06:17:31 PM by TXCraig1 »
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Offline HansB

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Re: My overclocked Roccbox oven
« Reply #4 on: May 02, 2018, 06:15:12 PM »
Guess I had it backwards, I could use a bit more bottom heat in my Roccbox.
Hans

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Offline overdo-everything

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Re: My overclocked Roccbox oven
« Reply #5 on: May 02, 2018, 07:00:33 PM »
That's very cool, but for what you ended up spending, why not get a Pizza Party oven instead?

I do see a Pizza Party oven in my future. At the time I ordered my Roccbox, Pizza Party did not yet have the gas option. From that starting point, the low incremental cost to tinker with what I had, and my inclination to tinker, led me down the path I took.

I doubt that roccbox floor is cordierite. I bet it's some sort of firebrick. Cordierite is WAY too conductive for Neapolitan which is why people see such a big change when moving to other deck materials.

I got the "Roccbox uses cordierite" from the Roccbox web site. But it makes more sense that you are correct and the website is just wrong. That would explain why I didn't see a big difference going to FibraMent, and why the stock oven is viable at all at Neapolitan temperatures.

I corresponded with Simone of Pizza Party about buying a slab of Biscotto Saputo that I could fit into my Roccbox. He seemed willing, but was out of stock at the time I asked. It would have been up to me to cut it to size. It would have been a complex fitment also because the thickness of the saputo is greater than the thickness of the stock stone. In the end I decided it probably wasn't worth the trouble, and I'd rather give Simone an order for a whole oven with the deck I need. That hasn't happened yet, but I'm holding on to the idea.

Guess I had it backwards, I could use a bit more bottom heat in my Roccbox.

That is interesting. I've seen that when I've cooked a pizza early in the warmup cycle, when the stone might read a high surface temperature, but has less energy stored throughout its thickness. Do you need more bottom heat even after the oven has reached equilibrium?

Chris

Offline HansB

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Re: My overclocked Roccbox oven
« Reply #6 on: May 02, 2018, 07:10:20 PM »

That is interesting. I've seen that when I've cooked a pizza early in the warmup cycle, when the stone might read a high surface temperature, but has less energy stored throughout its thickness. Do you need more bottom heat even after the oven has reached equilibrium?

Chris

Last time I preheated for about 40 minutes and would have like more bottom heat. I guess I'll turn the flame down a bit next time.
Hans

Offline stiks47

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Re: My overclocked Roccbox oven
« Reply #7 on: May 31, 2018, 01:23:17 AM »
That's very cool, but for what you ended up spending, why not get a Pizza Party oven instead?

I looked at the Pizza Party oven but the gas burner out the front is not aesthically pleasing. Cost wise, the Roccbox is half the price. And I have a homemade wood burning oven. I have to say, not having to deal with fire management makes pizza parties much more enjoyable. If I was more interested in wood fire, I may have leaned towards Pizza Party as it seems to do both gas and wood well. The roccbox is quite difficult to get to temp on wood.

Offline ccgus

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Re: My overclocked Roccbox oven
« Reply #8 on: May 31, 2018, 01:01:48 PM »
The roccbox is quite difficult to get to temp on wood.

So one thing I've been doing for the past couple of weeks, is throwing a little 6" sliver of apple wood in the back of my Roccbox a minute or so before a bake. It adds a nice rolling flame and alters the flavor of the pizza just a tiny bit. Bakes happen a little bit faster as well, and things aren't underdone in the middle.

It's a nice little compromise if you still want to use wood in some way.

Offline stiks47

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Re: My overclocked Roccbox oven
« Reply #9 on: June 01, 2018, 12:27:23 AM »
So one thing I've been doing for the past couple of weeks, is throwing a little 6" sliver of apple wood in the back of my Roccbox a minute or so before a bake. It adds a nice rolling flame and alters the flavor of the pizza just a tiny bit. Bakes happen a little bit faster as well, and things aren't underdone in the middle.

It's a nice little compromise if you still want to use wood in some way.

Yes, I sometimes do the same. It is nice to get that wood burning scent. I haven't tried with a piece that big but will give it a go.

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Offline lelferreira

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Re: My overclocked Roccbox oven
« Reply #10 on: June 01, 2018, 02:43:17 PM »
Nice!!!

Could show us some pictures of your pizza with the fibrament? specially the bottom.

I got a pizza peel, so I can rotate it faster inside the oven but still getting some slightly burn bottoms around the rim. I would love to put a biscotto saputo in it

Offline bfr

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Re: My overclocked Roccbox oven
« Reply #11 on: September 08, 2018, 02:59:26 AM »
Roccbox stones are cordierite...or probably more specifically cordierite mullite ceramic.  A much simpler conversion of the regulator is possible with either the 0-5psi GasPro or 0-10psi GasSaf adjustable regulators available on Amazon. The 0-10psi is a simple swap: unscrew the 3/8" flare from the Roccbox burner and screw the new hose on.  The 0-10psi does suffer somewhat from a lack of fine adjustability but still is totally workable.  You are only using about 3/4 of a turn of the adjustable dial to go from off to a point that you probably don't really want to exceed. It is easiest to have the Roccbox knob on full, then set your adjustable regulator to a point that maxes the flame at the highest level you'd like it during baking.  Then in between pizzas you can turn the Roccbox knob down to keep from overheating your stone.  The 0-5psi is my preferred regulator however it does not come with the 3/8" flare fitting.  It was simple enough to cut it off and put one on. I agree that ideally you'd have about a 0-2psi adjustable regulator that is made for a low flow appliance but I have not found anything like that.  Realistically, the 0-5psi works great and for about $15 and 15 minutes of modification, you can't beat it.  Here is the 0-10psi in action before I switched to the 0-5psi: 

Offline bfr

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Re: My overclocked Roccbox oven
« Reply #12 on: September 08, 2018, 03:04:26 AM »
Here is the cutaway design image from Roccbox where it notes the stone is cordierite.  They also refer to it in their materials list as engineered stone.

Offline bfr

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Re: My overclocked Roccbox oven
« Reply #13 on: September 08, 2018, 03:22:09 AM »
It is also a piece of cake if you want to alter the burner orifice to change the gas flow rate.  Three 2.5mm hex head screws are all that need to be removed to access the inner guts of the burner.  From there a long socket can undo the supplied 1mm jet for those in 37mbar markets.  In the markets that get the 50mbar regulator the supplied jet is an .8mm.  The orifices/jets are M6 x .75, 8mm long and are removed with a 7mm hex socket.  You can buy them on Amazon with a .5mm opening...and then using engineers drills make them whatever size you desire.  This mod can also be used to convert your Roccbox to burning natural gas.

Offline Meatsweats86

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Re: My overclocked Roccbox oven
« Reply #14 on: October 26, 2018, 03:09:15 PM »
Great video and explanation on the regulator bfr. I am considering the Roccbox, but I live in MN and it gets below negative temps during the winter. I'm guessing if I go with the roccbox, the different regulator will be needed in order to achieve the 900+ degrees in the middle of winter.

Has adding that regulator caused any issued to the unit yet?

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Offline Meatsweats86

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Re: My overclocked Roccbox oven
« Reply #15 on: October 26, 2018, 03:19:02 PM »
Great video and explanation on the regulator bfr. I am considering the Roccbox, but I live in MN and it gets below negative temps during the winter. I'm guessing if I go with the roccbox, the different regulator will be needed in order to achieve the 900+ degrees in the middle of winter.

Has adding that regulator caused any issues to the unit yet?

Offline mux

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Re: My overclocked Roccbox oven
« Reply #16 on: February 19, 2019, 11:53:10 AM »
Question: was it ever resolved if the Roccbox stone is cordierite  or not? It doesn't seem plausible that it is cordierite, but bfr suggest otherwise.

Is there some special coorderite blend I am not aware of (cordierete mullite) and if so where can such a stone be purchased.

Offline HansB

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Re: My overclocked Roccbox oven
« Reply #17 on: February 19, 2019, 12:02:32 PM »
From their website:

Dense Stone

The thick porous stone floor creates the ultra dry environment necessary to bake from below, imperative for avoiding a soggy pizza, whilst the rolling flame bakes from above.

And:

Cooking floor
Engineered stone
Hans

Offline mux

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Re: My overclocked Roccbox oven
« Reply #18 on: February 19, 2019, 12:07:18 PM »
Thanks HansB, so the updated the website and this new description suggests it's some  firebrick/blend/mix, if I am not mistaken, but definitely not cordierite !

Offline stiks47

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Re: My overclocked Roccbox oven
« Reply #19 on: February 22, 2019, 12:31:07 AM »
Great video and explanation on the regulator bfr. I am considering the Roccbox, but I live in MN and it gets below negative temps during the winter. I'm guessing if I go with the roccbox, the different regulator will be needed in order to achieve the 900+ degrees in the middle of winter.

Has adding that regulator caused any issues to the unit yet?

I think it will work from factory just take longer to heat up. I think wind may have a stronger affect than the outdoor temp. Another thing you can do is buy an adjustable regulator. There is a 0-5 regulator on amazon you can use to get a bigger flame but be warned, you dont need to open it more than a quarter to a half to get a big ol flame.

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