Firebrick from Tractorsupply

I have been looking around trying to find local firebrick and found these at the local tractor supply. They are onsale for $2.39 each

US Stove firebrick at tractor supply

They say good up to 2000F. Anyone have thoughts on how well they will work in a RMH burn chamber?

Those are known as splits, half the thickness of regular heavy firebrick. $2.39 each is a good price. Ideally you would use them for building  the riser. In the feed tube  you would use regular full thickness fire brick. For your burn tunnel you would use insulated full thickness fire brick.  
You could use the ones you have located,  but they will not be stable during construction being only 1.25" thick
You haven't told us your general location but any larger city area will have a masonry supply house. That is the kind of place to locate fire brick of both thicknesses, also 50# sacks of fire clay will be there as well.

I'm in northern Utah about hour north of Salt Lake. The stove I am designing won't have a classic J tube. I'm hoping for a batch box with a burn chamber/ heat riser located above the box. I would love to build the batch box out of firebrick with a fireclay monolithic above it for the burn chamber and the heat riser.

I have been researching for over a year now on this project and still have lots of questions. I have been lurking here for a long time and have learned allot.

Hey Mike;  The Salt lake / Pocatello area certainly has a masonry supply house. Look in the yellow pages or on line locally for a mason offering to build fireplaces , call him up and ask where he sources his firebrick & fireclay. Have you looked at the shippable premade batch box kits that permies member Brian James is selling ? Ceramic fiber boards seem to me to be the newest, possibly best insulating material to use.

I find that horendously expensive for splits.

Markets differ, Max Around here (upstate New York), $2.39 would be a good price for splits. Hardware stores sell boxes of six for $18 or sometimes more. Full firebrick are often less expensive than splits (bought new). You can find them used for much less, but seldom used splits.

How usable is a 2000F brick? That's what they are rated for. Would they work in the batch box for holding the fuel?

Well, I'm still not sure if I can use these for a batch box burn chamber. I picked some up anyway since they are still on sale and they were being put in storage at Tractor Supply for the season. They where setting up law mowers getting ready for spring...

I ended up buying 30 of them. I have another project for a wood fired mini oven if I can't use them on my heater build.

-Mike