batchbox insulation questions

My husband and I have been studying dozens of batchbox rocket stove builds. We've noticed that some of them insulate the batchbox, others don't. It's raised some questions.

1) What is the advantage to insulating the batchbox? Is there an advantage not to? Disadvantages either way?

2) What is the best insulation material? We see a lot of rock wool used, but some other materials as well.

Hi Leah;
I am a proponent of using insulation around your Batchbox.
It keeps the heat in the core, to quickly develop the high temperatures needed for complete combustion.
Is insulation required?  No, it is not. Your core will come up to full heat no matter what, but it will get there faster and burn cleaner if it is insulated.
I prefer the #8 density Superwool as the insulator of choice.  Rock wool is itchy, and it is much cheaper, but it will do the job.  

Leigh Tate wrote:1) What is the advantage to insulating the batchbox? Is there an advantage not to? Disadvantages either way?

Insulating the firebox itself can be done but it won't add much. The riser however, being the afterburner device, do make quite a difference when it's insulated. This afterburner function will kick in sooner, helped also by less mass in the riser.

Leigh Tate wrote:2) What is the best insulation material? We see a lot of rock wool used, but some other materials as well.

Best insulation material to date is Morgan thermal ceramics superwool, in my opinion. Rockwool will work, but tend to disintegrate above 500 ºC (932 ºF). The binder of rockwool is burning away much sooner, though.

Thank you Thomas and Peter!

We are actually thinking about the DSR design, so no riser. Will the same guidelines about insulation apply to it as well?

Leigh Tate wrote:We are actually thinking about the DSR design, so no riser. Will the same guidelines about insulation apply to it as well?

In general, yes. The DSR2 and DSR3 are very different though, which one are you planning to build?

So far, I think we've only seen sketchups for the DSR2, so that's what we're looking at. I've seen threads discussing the DSR3, but photos are somewhat random and I can't visualize it.

Leigh Tate wrote:So far, I think we've only seen sketchups for the DSR2, so that's what we're looking at. I've seen threads discussing the DSR3, but photos are somewhat random and I can't visualize it.

OK, a DSR2 then. As all batchrockets are very specific, this one isn't an exception. The core will run clean on its own with just a 3-foot piece of larger stove pipe on top. Insulation around the entire core is easy because it is errhhmm... just a double shoebox.