Fire Brick Heat Riser

Has anyone asked about how the torus is affected if the heat riser is built from fire brick? I was wondering if the efficiency would be adversely affected with a square "burn tube" made from brick. I have no experience with building an RMH other than the one out in the yard which was just for testing. I used a 6 ft. piece of 6" pipe just to test the horizontal burn. It seems to me that fire brick would last much longer than a metal heat riser. I am pretty good at laying bricks so they are plumb but doing a round tube that small with bricks isn't very practical.

Dave fire brick is what you use for a permanent stove that you dont plan to tinker with... Ever. The other types of heat riser where developed to make building easy, make cast-able heat risers, and or make something that could be fiddled with. brick heat risers work fine and will make an indoor stove perform better in some ways. the torus is not affected much that i can tell.

Ernie Wisner wrote:Dave fire brick is what you use for a permanent stove that you dont plan to tinker with... Ever. The other types of heat riser where developed to make building easy, make cast-able heat risers, and or make something that could be fiddled with. brick heat risers work fine and will make an indoor stove perform better in some ways. the torus is not affected much that i can tell.

Thanks Ernie. I guess I had better get started preparing the spot in my place where I intend to build my RMH. I don't plan to take it with me but rather make it a selling point when I put this place up for sale.

I am building a SIP house and hope to never move from it and I'm trying to understand the critical concepts behind a RMH. I just to the Podcast that came out this week and will try not to anger Ernie with my questions Yes I am one of "those people" that haven't tried to build one yet and am already thinking about changes.

Does a fire brick heat riser still have to be insulated or do the bricks provide enough insulation?

Is it important for the next layer outside on the heat riser be metal? Or put another way is the choice of a steel drum functional or mainly for cost savings? Is the cooling/heat transfer of metal required for this system to work?

I did notice from the podcast that some of the choices you make are due to needing to teach a workshop for people that are not masons. While my brick laying experience is low, I have access to people that do it for a living. Of course trial runs will be conducted outside or maybe in a metal pole barn on a concrete slab.

the brick needs to be insulated if you are using perlite and full sized bricks this will mean you have to use a 30 gal or 55 gal drum for the bell. with half bricks you can still get away with a 120 lb grease can.

no need to metal in the heat riser at all; and i recommend brick if it can be gotten. RMH's are designed to use the waste stream as much as possible; sometimes you cant get bricks, sometimes you cant get ducting, so we develop the stove to use other materials if we can.

As i said in the pod cast just build one by the numbers first and fire it a couple times. at least get a base line to make changes from. i dont have a problem of folks thinking of changes its making them before they have any experience at all.

I am using a 30 gallon drum. 55 gallon is too large for this space. I have a brick wholesaler here that caters to the trade so I have access to fire brick. There is a good size stack of fire brick out in the yard. This project has been on going since last year. I buy a couple dozen fire bricks at a time every other month or so until I have enough for my needs. I am not a stone mason per se but have enough experience working with those types of materials. I used to install wood stoves as an income stream. Laying the brick for heat shield included. I never laid actually did a brick chimney other than a very short one in a BBQ.