So after checking in on this thread a couple weeks ago, I was intrigued dwight's mention of the ceramic bricks for a grill. In the past I have tried to find inexpensive radiant tiles for my RK system without much luck. I was really excited to find a plethora of options available on Amazon for the grill tiles.
This is a shot of the inside of my RK setup. I've got all the back vents sealed up, as well as and seams or holes that could be closed off. I also have a couple of fire bricks in the bottom of the grill to help add some thermal mass. In the first pic you can see the stock heat spreaders that go over the burners. The second pic shows the inside with the heat spreaders removed:
I searched through what Amazon had to offer and finally settled on
these ceramic tiles. I chose that particular tile because it was thicker than most others (~5/8") and the dimensions of the tiles would cover the majority of the area over the burners, which was 17"x24" in my grill. I also purchased
this adjustable grate so that the tiles would have a nice plat spot on which to rest.
The rest was pretty easy. I sized the grate to fit over the area where the heat spreaders normally rest and then laid the ceramic tiles directly on top of the grate:
Couple of shots with the drum installed. The tiles covered probably 90% of the area of the grill. Couldn't ask for a better fit:
Next I plan to add some handles to the grate to allow me to remove the setup for cleaning. I also plan on securing the tiles to the grate so they don't fall off and break when removing them.
So how did it work? Not sure just yet. It certainly takes a bit longer to heat up, but it also seems to heat hotter at the same heat setting. Heat retention after opening the hood is much better. Unfortunately, the battery on my IR thermometer died, and I was not able to get temp reading from the tile itself. The only roasts I have done so far have been test roasts with old, junk beans in the drum, so I can not compare "tiled" roasts with "untiled" roasts. I plan on roasting 2 batches of the same coffee for comparison. Stay tuned.
Here are some more pics of the setup: