Pellet Powered Brick Pizza Oven


After reading about and then constructing several temporary brick pizza ovens over the course of a couple of years, I decided to build a permanent one this fall (2012). I had the idea that I could take a pellet grill mechanism and use it as the primary heat source. My feeling was using pellets would be more elegant than a straight firewood. It should be easy to temporarily or permanently convert the oven to a traditional firewood oven if it doesn't work out.

I should point out there were two books in particular which were very helpful for this project:

I ordered a SmokeDaddy Grill pellet mechanism from Pellet Pro Grills. The folks at Pellet Pro Grills were very helpful and supportive of my somewhat unorthodox use for their product! (Special thanks to Dennis for his help!)


(click on the pictures below for a larger image)

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Here is the spot off of my back porch where I'll locate the new oven.

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The first thing to do was clear the weeds, dig out the top soil and pour a 4 foot square concrete pad to support the oven.

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I started with a layer of no-mix fast curing concrete. I used 4 foot fencing pieces as the form.

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About half way through, I laid these pieces of rebar in to enhance the strength of the pad.

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I used crack resistent concrete mix, and dyed it brick-red for the top half of the pad.

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I pushed a large nail into the center of the wet concrete and used a string and stick to mark out a circle.

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When the pad was fully set, I stacked 16 cinderblocks inside the circle.

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The cinderblocks form the core support structure for the oven.

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I probably should have drawn the circle a couple of inches bigger.

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It worked just fine anyhow as a guide to help me center the blocks and later, to lay in the bricks.

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I had a bunch of salvaged bricks that were layed out as a sort of patio where I keep my trash cans.

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I had to clean all of the bricks off after prying them out of the ground..

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It was a nice day, and kind of fun.

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It took a long time though.

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Next, I stacked the bricks to make sure I had enough for the base.

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Yep, I had enough. It took 195 of them to build the base.

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I decided to color the mortar red.

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This was my first ever brick laying project. I learned quickly that one should wear gloves.
The lime-burns are no fun if you don't.

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I filled the base with 22 bags of all purpose sand.
I topped it off to make a solid, level shelf with a blend of inexpensive clay kitty litter and portland cement.

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Portland cement, by itself does not hold up to high heat very well.
I confirmed this in my earlier oven experiments.
My thought is adding the bentonite clay will make something closer to a refractory.
At the least, if the heat gets high enough to disintigrate the cement, it may counterbalance that by fusing the clay.

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Next I built the armature (inner forms) for the dome.
My dome radius was a little over 15 inches.
I used a yard stick to draw the base on a large cardboard box.

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I cut a bunch of cardboard half-circles (12 inch diameter) and a few wooden blocks to glue up a door frame.

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I cut a bunch more quartercircles with the same diameter as the base and make the dome.
I held the whole thing together mostly with (black duct) tape.

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I set firebrick in around where the pellet stove mechanism would be.
I found that the regular bricks I'd used in my earlier oven experiments were very brittle.
The firebrick was not as brittle after multiple firings, so I used it where I expected the oven to be the hottest.

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I topped off my base with a layer of brick.
Then I mortared in an outer ring of brick where the floor would be.

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Checked to make sure the armature fit nicely.

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Following the advice in the Russell Jeavons book, I decided to not mortar in the actual cooking floor.

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All of the bricks once the base was done were solid bricks.
The guys at Columbus Builder's Supply (where I bought them) called them "105's".

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This was actually one of the trickiest parts in this project. ... Fitting rectangular bricks into a round hole.

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They fit in there pretty tightly.

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I sanded them as smooth as I had patience for using files, and a 60 grit diamond sanding block.

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I had to cut the armature to fit over my firebrick.

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I mixed all the mortar for the upper half of the oven with kitty litter.
The kitty litter dissolves into a fine mud when you get it wet. I did not have to mechanically pulverize it.

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I cut a bunch of half-bricks to make the door.

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Then I started making the dome.

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I ran out of time for the day and had a bunch of mortar left, so I plastered the dome with it.

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I actually liked this look.

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I finished off the dome a few days later.

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I left a hole in the front, just behind the door for a chimney.

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I plastered it. The mortar was not a perfect color match.
I piled some bricks up so I could visualize how the chimney was going to work.

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There were lots of these little pill bugs in my brick pile.
Many of them were sadly sacrificed to the brick oven gods during this construction project.

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I set the second layer of bricks around the dome.

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I filled in every gap with bits of brick and lots of clay-enhanced mortar.

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I left a channel for the chimney across the top from front to back.

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The weather was 40 degrees F, and raining. Summer was definitely over.
I was freezing, the mortar was running in the rain.

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I capped the top of the dome flat.
My intention is to put a stone carving (dragon?) there.
I won't finish the carving until spring (at the soonest!).

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It finally stopped raining. I burned out the armature.

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There are about 250 bricks in the top half of the oven.

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I am using a few leftover firebricks as a door until I have time to make a nice one.

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I hope to have the time next spring or summer to carve some of the bricks on this oven.
I had pretty good luck with brick-carving experiments using diamond bits in a rotary carving tool.

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The chimney is stacked for now. It is too cold to mortar in more bricks.
Plus I'm about 10 bricks short. I need to get a few more before spring so I can finish the chimney.

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I made a wooden stand for the pellet stove mechanism.

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I bolted the stand to a stepping stone.
Here is the SmokeDaddy unit from Pellet Pro in place behind the oven.

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Just like you season a cast iron pan, I thought I'd season the bricks.
I've been coating them in a layer of vegetable oil before lighting the oven.

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They are forming a beautiful non-stick surface now.

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Fire!

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Flatbreads!

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Me! Baking bread.

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Bread!

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The pellet stove flame spits a lot of sparks.
I'm trying a steel screen in front of the flame to try to minimize the sparks that get on the food.
The screen shown (typically used to keep debris out of household gutters) is too coarse to be as effective as I'd like. I need to find one for fireplaces.

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One of the challenges with this pellet powered oven is that it takes a really long time to heat up with just the pellet burner.
I can get it to heat up faster by building a temporary stick fire, but I'm trying to avoid that messy process.

I upgraded the auger motor from the default 1.5RPM to 2.0RPM.
Feeding the pellets in a little faster makes it burn a little hotter.
Unfortunately, after 5 hours, the floor is still barely 450°F. (I'd like to get it to 600°F, and preferably in 3 hours.)
It still makes great pizza, but it would be better if it were hotter, and hotter faster.

Thanks for letting me share my big project for this past fall with you! I'll post updates as the oven evolves over the new few months and years. Check back again sometime!

Some of the to-do's:

  • Finish the chimney
  • Add a stone sculpture to the top
  • Carve some of the bricks
  • I've identified several spots where the insulation in the oven could use improvement. I need to work on that.
  • Investigate ways to pre-heat the air for the blower, perhaps a loop back from the chimney?
  • Investigate other brands of pellet fuel. Perhaps some burn hotter than others?
  • I'll post recipes on our recipe blog when I come up good ones.