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Author Topic: Traeger pellet grill with GMG attachment  (Read 15876 times)

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Offline PelletPizzaJoe

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Traeger pellet grill with GMG attachment
« on: June 22, 2017, 10:23:13 PM »
Green Mountain Grills makes a pizza making oven  attachment that fits in their own pellet grills.  Well I decided to see if it would fit and work in a  Traeger Texas pellet grill I have that's been collecting dust.

Well it fits...  gets up to 970F when running the grill on high.

 I think the heat is a bít too heavily biased toward the bottom,  but I've only cooked on it once so far and really tried to cook an American style pizza at too high of a temperature  ( 720F ), I burnt the bottom.

Anyway it shows some promise

Offline 02ebz06

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Re: Traeger pellet grill with GMG attachment
« Reply #1 on: June 23, 2017, 11:03:16 AM »
Glad it worked in your grill.
There is a long thread about those on the PelletHeads site.

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #2 on: June 23, 2017, 11:58:13 AM »
Glad it worked in your grill.
There is a long thread about those on the PelletHeads site.

Yeah, I've read the thread... just added a bit to it.   There are only spotty bits of information about how to best use it.   Now, my first pizza on it , that I showed above... was admittedly cooked at too high of a temperature for that type of pizza.  I normally do them at closer to 620F , rather that the 720F the stone was reading last night. I typically bake for about 6.5 minutes at 620F, and last night I went about 5 minutes at 720F... the bottom was REALLY charred... ( still ate it though ).  My daughter remarked that I should make pizza like that more often, cause she liked the different sort of flavor and texture that it had.   Even so, IMHO it was definitely over cooked on the bottom.

   I've two more dough balls in the fridge now, hopefully tonight I'll be able to do better.  I know for sure this thing has a lot of promise, just not a lot of user base with good pizza skills that have shared a whole lot yet from what I've seen.

   Meanwhile, knowing that I can get the stone up to 970F, now I have notions of doing a neapolitan pizza... probably going to have to get my Caputo 00 out and learn some new skills.

Offline old_alex

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Re: Traeger pellet grill with GMG attachment
« Reply #3 on: June 27, 2017, 01:41:15 PM »
When the bottom is done, you could dome the pizza (use your peel to raise the pizza high in the oven so that the heat at the top of the oven cooks the top). I do it sometimes on my blackstone when it is not cooking even.

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #4 on: June 27, 2017, 03:25:18 PM »
One of the things I have done... is to cook the pizza for about half the total time, maybe a little more then half, then put it on a pizza screen and slide it back in, the screen keeps the crust off the stone and allows the top to keep cooking, this worked reasonably well....

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Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #5 on: June 27, 2017, 03:31:56 PM »
However I've already started to modify this, by adding another stone in the top. This gives me some radiant heat from the upper stone.

I'm still tweaking the upper stone attachment scheme,  but early testing has me optimistic.

Offline 02ebz06

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Re: Traeger pellet grill with GMG attachment
« Reply #6 on: June 27, 2017, 03:35:13 PM »
Looks like a great mod Joe.

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #7 on: June 27, 2017, 08:06:27 PM »
850F , 2 minutes or so, this with my dual stone modification. Still a little hotter on the bottom. But this was a darn good pizza.

Offline Jackie Tran

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Re: Traeger pellet grill with GMG attachment
« Reply #8 on: June 27, 2017, 09:48:10 PM »
Very cool!  Thank you for posting this info. I may need a pellet grill sooner than later.   Any guesses if this will work in just about any pellet grill?  I could see myself getting a camp chef or firecraft grill

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #9 on: June 28, 2017, 07:40:39 AM »
It might work on the Camp Chef, I'll look into that a bit more...   It for sure will not work on the Firecraft Q450.

  It will really only work on pellet grills that have the firepot centered , and that are a minimum of 20x20...  It was designed for the GMG Daniel Boone and the Jim Bowie grills, and sill likely works best in those grills because of the shape of their body, their bodies extend straight upward before turning in toward the top, this yields more height near the front and the back of the grill, allowing you to fully close the lid with one of these inside. On your typical 20" barrel shaped design, the lid on the grill won't quite shut all the way, because the height of the pizza oven attachment is a tiny bit too high. 

    So,the firepot in the Camp Chef is basically centered, so that is not a issue... what might be a issue on the Camp Chef, is the lid.  The lid on the Camp Chef slopes downward at a odd radius , so I'm not sure just how well the pizza oven attachment will fit inside with the lid closed. You don't absolutely have to have the lid closed to use the device though... in fact , if there was a door on the front of the pizza attachment, closing the lid on the grill would be more or less irrelevant.   Either way, I may try to find a local place that sells the Camp Chef and do a measurement...  If it fits well, it may actually be the ideal grill to use this in, because of the way the ash dump feature is on the Camp Chef. Right now, on the GMG, or most any other pellet grill, you will have to completely remove the GMG Pizza Oven attachment to be able to clean out the ash from the firepot.  On some grills this doesn't need to happen every single cook, but every other cook or so is necessary.    Bottom line, I'll get back with you on the Camp Chef.  ( sometimes you can find a Camp Chef SE for under $300, Walmart at times has had them on 'clearance' for $200 and sometimes even less ).

   It's a shame someone doesn't build a pellet grill with part of the design intended to be used for a oven attachment like this.  GMG has a pretty cool idea and it does work, however there are some things that could be improved upon.   I'm seriously considering finding a local fabricator to help me build my own custom pellet fired  pizza grill... Not like the Uni... but a real full blown forced air pellet grill, one that would be capable of 1000F on a regular basis with ease and run for hours and hours without any significant human attention...  I think if there is one flaw with the GMG, it's that the nature of it is, that the bottom stone is always going to be hotter then the air above it...  If someone could figure out how to get more of the heat around the sides and up across some mass at the top, and distribute the heat better, it'd make a wonderful oven, similar to a brick oven... well in fact, I don't really understand why someone doesn't make a brick style oven with wood pellet grill firepot design, rather than real wood.

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Offline Jackie Tran

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Re: Traeger pellet grill with GMG attachment
« Reply #10 on: June 29, 2017, 07:23:00 AM »
Great detailed post.  Sorry if I missed it earlier.  How long does it take to heat up to 650F?   I can do a lot with 600-700f. 

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #11 on: June 29, 2017, 08:10:02 AM »
Great detailed post.  Sorry if I missed it earlier.  How long does it take to heat up to 650F?   I can do a lot with 600-700f.

  No, you didn't miss it earlier...  but it just so happens I have a good bit of information on how long it takes to heat up...   I may have to go through some of it to present it better, or even gather some more... For now, I'll show you how long it took for my modified version of this to heat up.   I think the data would be more or less valid, for a unmodified version of this device too, but I need to go back and look at other data I collected.

   Before I go further...  Several GMG grill owners report that they their Pizza Oven attachements get up to temperature in 20 to 30 minutes.  This measured with a IR gun pointing at the surface of the stone.   I myself , have seen IR gun readings hit 600F in as little as 20 minutes, so I don't question those numbers at all.  However, my data and experience with other pizza making tells me that it takes a bit longer to really saturate the stone with heat.

   So,  this graph shows some data I collected with my modified version of the device...  What I see when I look at this, is that the stone and/or air temperature near the surface of the stone will get up to about 550F in as little as 30 minutes, but then the fact that that temperature reading continues to slowly climb up to where it peaks out around 625F after about a hour, tells me that the materials are indeed still continuing to gather more heat during the first hour.  Realistically I can say that the grill attachment is fully saturated with heat in about an hour.

   


Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #12 on: June 29, 2017, 08:23:48 AM »
Here's a slightly different view of that same data, and a bit more information about how it was gathered...

 I have a device called a Fireboard, that allows data collection of temperatures using up to 6 different probes.  I own 6 ambient probes, and two food probes... but anyway for this data collection , I used 4 probes, one placed near the sensor the grill uses to control temperature, if you look at that sensor data, that sensor only saw roughly 285F temperatures... I had two other probes that were sitting on top of the main oven attachment stone, both placed near the center of the stone, front to back, and then each of the two were roughly 4 inches from the sides of the stone ( stone is 16" wide, 14" deep ).  I'm unclear why there is a difference between the temperatures on the right vs left side here,  but to some degree I don't care about that.  The fourth measurement was taken with a probe sitting on top of upper stone, this area is more or less isolated from any direct flame or heat that comes from flames, it's all heat that is coming off the top of a 3/4" thick 'Pizza Grourmet' pizza stone ( 25 year old stone, you can't buy any more )... so anyway, if you watch that last reading, It gives you some idea of when that particular stone REALLY became saturated with heat.

The very beginning of this graph is roughly 8:05AM
« Last Edit: June 29, 2017, 08:31:58 AM by PelletPizzaJoe »

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #13 on: June 29, 2017, 09:01:04 AM »
Here's a bit more data that I collected on the first day I had the GMG pizza attachment...   So, this was before I had added the upper stone.   Don't pay too much attention to the 'near grill  probe' temperatures, when I did this test, that probe wasn't really close to the grill's probe, I think I was running the grill set to a temperature of roughly 250F, but I can't remember for sure.    I do know that eventually, IR gun reading on the stone hit just over 500F during this testing.

 By the way... in this test, I was purposely trying to keep the temperatures of this device around 500F, it was new to me , and I did not want to try and immediately hit it's maximum capability. I can assure you this device can easily hit 700F, in fact I've seen stone readings taken with IR gun hit 920F in my grill.

  The first 5 minutes of this graph, are as the pellet grill is starting up... it takes a while before the pellets catch on fire, however you can see in this graph that the temperatures seen inside this pizza attachment rapidly climb to over 450F, that first initial point where the reading from the top of the stone hits 480F, that occurs at 4:39, just ten minutes into this , and only about 5 minutes after the fire really got going in this grill. That same temperature sensor read 510F at 5:15PM and never read much higher throughout the remainder of this test.

  In this particular test, the 'on stone' probe was placed dead center of the stone.  The probe labeled top of attachment, was also at the center of this grill attachment, but was stuck through a hole in the top of the stainless steel dome ( where the handle is supposed to attach ). 

   What I see when I look at this data is...  this attachment rapidly gets up to solid 450F temperatures, when running under these particular conditions... to get the last 50F temperatures once again takes roughly 45 minutes to a hour.  It's not unreasonable to assume that the true saturation of the stone and such , takes in the neighborhood of 1 hour.  However, I'm confident you could actually cook a pretty darn good pizza in as little as 30 minutes with this setup.    I still feel that this device, like virtually every other device which uses a heat source that comes from bellow the stone, will pretty much always have temperatures on the bottom of your pizza being hotter than the top... however, I don't think this device would be any worse than any other device on the market, and may very well be as good or better than most. 

   
« Last Edit: June 29, 2017, 09:04:34 AM by PelletPizzaJoe »

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #14 on: June 29, 2017, 09:22:24 AM »
And here is the last bit of data for now... pretty much gets directly to the heart of Jackie Tran's question...   How long does it take to get up to 600~700F

Well first let me say, my temperature probes have a maximum temperature rating of 752F, and I know this grill attachment will easily go above 752F, so I was being somewhat conservative while collecting this data, and in fact near the end of what is shown here, I purposely turned the grill down a little , because i could see that I was going to hit the upper limits of my measuring capabilities. If I had ran this grill at full bore, it would have hit these temperatures a little quicker then it did... and went well beyond the 700F or so I was shooting for.  But once again, I believe that realistically it will take about 45 minutes to a hour to really saturate the stone with heat in one of these.

  Oh, and for the record... I estimate it used about 3 pounds or less of wood pellets to get up to this temperature, I'll have to do a more detailed test to figure out exactly how many pellets I use.  I have a source of pellets that cost me about $0.13/lb , so the cost for me is really not that bad.  ALso... I have some pellets that are part wood and part charcoal... I could run this grill even hotter than I am, if I desire. :) but I won't be able to accurately measure just how hot it can get with these temperature probes. I predict I can get this attachment to heat up the stones to over 1000F.



« Last Edit: June 29, 2017, 09:25:25 AM by PelletPizzaJoe »

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Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #15 on: June 29, 2017, 09:50:41 AM »
OK, so I realized that some of you may not understand the nature of a pellet grill,  how they work, and how it may relate to the question of 'how fast can you get to 700F'...

  OK, so realize that pellet grills are traditionally designed to operate at temperatures between 150F and say 350F,  and to hold the temperature for a long period of time, so you can cook meat( mostly meat). Their controllers intentionally adjust how many wood pellets get fed into the firepot.   If you set the grill up such that it runs at full speed, it will reach higher temperatures and do it rather quickly. Just how quickly depends on the grill's design... basically the larger the firepot and the faster the auger is capable of running, the hotter the grill's maximum temperature can be..   

  Also, with regard to this pizza oven attachment, you must realize that pellet grills traditionally take the heat from a single firepot and try to distribute that heat over a large area, as evenly as possible. There are many methods to accomplish that...   So anyway... In the grill I'm using this attachment in, the standard cooking surface covers roughly 20x34" ( 680 square inches ), in it's stock configuration the Traeger Texas will hit a maximum temperature of about 450F.    Meanwhile this Green Mountain Grills Pizza oven attachment, actually uses a metal box that fits above the firepot, and concentrates the heat coming off the firepot into a area that is roughly 285 square inches, and then puts a lid on top of that to reduce the total volume greatly... this is how this attachment is capable of producing temperatures up toward 1000F, they are basically concentrating the entire output of the firepot into an area that's probably less then 33% of the grill's total volume ( the grill the attachment sits in ). 

   But anyway... with most of the the testing I just showed you, the grill is really only feeding pellets into the firepot at a rate of about half of what it's maximum feed rate is.  The reason I mention this now, is because if you run at 100% from the very start, you can heat this thing up much faster... but eventually you'd need to turn it down, unless you really were trying to use it close to 1000F.  Just keep that in mind when you look at those graphs above.

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #16 on: June 29, 2017, 08:10:25 PM »
I collected some more data tonight, I ran my Traeger Texas at full speed from start to finish.  Measured how many pellets were used too...   

3 pounds of pellets were used during my testing tonight, which lasted just over a hour, the grill was running at maximum feed rate during this entire time. ( or until just after I finished baking my pizza at roughly 7:00.

Forgive, me but I got the labels on the 'On Stone Right' and 'On Top of Top Stone'  swapped, and at this point I haven't found a easy way to fix the labels.

I had to pull the temperature probe from the right side of the stone when it hit 725F, so that I didn't damage that probe.  when I removed that probe, my IR gun was reading 660F when I pointed at the lower stone...  A short time later the probe on the left side also reached 725F and I had to pull that one too... I checked with IR gun again, and it was reading 770F.   I continued to let this attachment heat up as I prepared a pizza... I had to pull the probe that was on top of the top stone to get my pizza in the oven, my IR gun was reading 900F on the stone at that time.   

   I continue to burn the bottom of my pizzas, perhaps due to my dough formulation, or whatever...   but anyway, I am very new to trying to cook pizza at 900F+ anyway, so I'm not ready to blame this on the device... mostly at this point I'm trying to share what I've been learning about this device, not to show you how great a pizza it can or can not make.

  At some point this weekend, I will take my stone out of the top of this attachment and do some testing with it in the stock configuration.



« Last Edit: June 29, 2017, 09:00:25 PM by PelletPizzaJoe »

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #17 on: June 29, 2017, 08:24:45 PM »
Pizza tonight was nothing to brag about.  Trying to do pizza at 900F+ is all new to me...

My daughter loved this pizza though. Toppings were ham and leftover bratwurst , apparently my daughter really loved the bratwurst, first time I ever put it on a pizza. 

180 grams Caputo 00
112 grams water
3.6 grams salt
1.8 grams sugar
0.7 grams IDY

Baked about two minutes,  bottom burnt, top not bad... should have got it up off the stone after the first minute.

« Last Edit: June 29, 2017, 08:36:49 PM by PelletPizzaJoe »

Offline barryvabeach

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Re: Traeger pellet grill with GMG attachment
« Reply #18 on: June 30, 2017, 06:57:27 AM »
Nice presentation of data.  I haven't seen that device, but in general, it is pretty hard to cook a pizza with a stone at 900 degrees, it just results  in a burnt bottom, unless you have a stone that has a very low conductivity, like the saputo stone that is an option for the pizza party.  I use a blackstone, and find anything much over 750 F is too high for me

Offline PelletPizzaJoe

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Re: Traeger pellet grill with GMG attachment
« Reply #19 on: June 30, 2017, 08:24:43 AM »
Nice presentation of data.  I haven't seen that device, but in general, it is pretty hard to cook a pizza with a stone at 900 degrees, it just results  in a burnt bottom, unless you have a stone that has a very low conductivity, like the saputo stone that is an option for the pizza party.  I use a blackstone, and find anything much over 750 F is too high for me

   Yeah, well at this point my best pizza's off this have come at temperatures between 600F and 700F, but then I haven't yet cooked any crust that had zero sugar in it, so I'm still wondering what results that might yield. 

   But yes, your right in that at this point it seems one solution would be to find a stone for the bottom that does not conduct heat so well, and I also think that having a dome made out of some material ( possibly cold rolled steel ) , that will reflect and/or radiate heat really well, might be helpful.

    One way or another, I'm confident that I can find a way to make decent use of this device in my old Traeger.  However, it's also gotten my mind spinning about how much better something could be if it were actually designed more like a wood fired oven, where the firepot were offset from the baking area and in horizontally inline with the baking area...   I'm seriously considering building myself something, but most likely I won't find time to do it this summer.

   I will be looking into trying to find a stone for the bottom that has lower conductivity.  Thanks for your comments Barryvabeach.

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