fire brick for riser

I have doing a lot of reading here on heat risers. Before I found this forum,I was going to use a piece of 6" Sched 10 steel pipe and an 8"piece of sched 10 with perlite or vermiculite for insulation between the two,sealed with refractory cement. ( i work in the fire protection industry,so parts are free) After all the reading, it seems that this set up is doomed to fail.  Is fire brick pretty much the best way to go?......Larry

Larry, similar to using fire brick.... because I have an unused  fireplace,  couldn't I build a rocket cook stove,
or mini mass heater, with the exhaust firebrick built into the existing back corner of the chimney. Seems like
it would be lots of mass and safe venting.  Just pondering...

Larry Bock wrote:I have doing a lot of reading here on heat risers. Before I found this forum,I was going to use a piece of 6" Sched 10 steel pipe and an 8"piece of sched 10 with perlite or vermiculite for insulation between the two,sealed with refractory cement. ( i work in the fire protection industry,so parts are free) After all the reading, it seems that this set up is doomed to fail.  Is fire brick pretty much the best way to go?......Larry

Larry, a mixture of refractory cement and perlite can work well. You just have to remove the inner tube, as it will break your cast, due to faster expansion rate than refractories.

J. Burkheimer wrote:Larry, similar to using fire brick.... because I have an unused  fireplace,  couldn't I build a rocket cook stove,
or mini mass heater, with the exhaust firebrick built into the existing back corner of the chimney. Seems like
it would be lots of mass and safe venting.  Just pondering...

J there's possibilities. I have a few drawings here, of chimneys with plunger tubes. You will have to search. There's a thread with old thirties photos.

I have helped two guys do things along those lines.

http://donkey32.proboards.com/thread/2076/fireplace-batch-box-conversion

http://donkey32.proboards.com/post/13115/thread

A pic of your fireplace would be welcome.

Im a newbie here. It seems that from a safety stand point , I'm better off with fire brick. And to think how much of it I ran across on job sites when I didn't need it. Lol... Larry

Larry Bock wrote:Im a newbie here. It seems that from a safety stand point , I'm better off with fire brick. And to think how much of it I ran across on job sites when I didn't need it. Lol... Larry

Larry, the advantage of firebricks, is that they are foolproof, and failproof.

I have no problem using firebricks but it seems that I read they will eventually break down. I'm just looking for a permanent solution. Maybe just build it so it's serviceable.

Well, as with any wood fired appliance,  being serviceable is a good idea.

Nothing lasts forever, but firebrick will last longer than any other available material. Its lifespan in a home RMH will likely be measured in decades.

Jeffrey Sullivan wrote:I have no problem using firebricks but it seems that I read they will eventually break down. I'm just looking for a permanent solution. Maybe just build it so it's serviceable.

I WILL eventually break down. LOL.  All I need is to have one of our resident experts say.   " go buy the fire bricks"and you will be fine.  The burn tube seems to be the critical component from what I have read. I am sitting in a Home Depot parking lot as I post this.   Larry

Ps how many will I need if I want to do a standard 24" riser?

Hi guys, I have read many threads, as many as I could find in the forum on rocket stoves, cob ovens etc. I have also read the thread about the metal heat risers and I am glad I did. The question I couldn't quiet get a clear perspective on is how firebreak compares to cob in heat rises. I understand there are many different recipes for cob and qualities, But assuming a very good cob mixture, How do you Think it compares to firebrick regarding longevity and insulative qualities? On top of that I wonder, If used in a Black oven situation, Can you imagine a difference in odor and flavour coming from firebrick vs cob?

Salut Brian.

Well, firebricks, if full firebricks, take a long time to heat, so a heat riser made of firebricks usually smokes a bit more at startup, thought, this is depending on what's opposed to it. Like highly insulative cob, against cob with stones in it. Best bricks to use, are insulating firebricks. Cob longevity, in the highly insulative range, is usually not that durable. Compared to bricks.