I am assuming you want the clay to fix your bricks together, the standard grey potters clay will be more than adequate as it is normally around 25-28% alumina and fired to around 2200f in a standard kiln.
I mix mine with 50% silica sand and water to make a nice mix, the thing about clay is it doesn't really stick anything together very well at all!
When it is wet the clay will offer a pretty good strong bond but when it drys out you can just break the seal very easily so you dont actually need a high quality, high alumina fire clay to bed bricks together.
Basically the higher the alumina content the higher temp it will take before it turns into a brick!
So the brown ‘earthenware ’ clay is fired to around 1700f and standard grey potters clay is fired to around 2000-2300f
So most folk building a rocket stove, use the clay to seal and stabilise the bricks together, to fill gaps and level out courses.
However once it has been heated and full dried, you can quite easily dismantle what ever you have built and clean up the bricks.
Personally I am not a big fan of using clay because it is very messy and can mark the brick face making your work look scruffy! ( i build pizza ovens for a living)
If I am using new clean fire brick then I use fire cement in a tube fitted in a mastic gun, if I am using red clay brick I use what is called ‘home brew’ that is a mix of lime, cement, sand and powdered clay.
Home brew is very easy to use but has an upper limit of around 600c .
If you are not really bothered about very neat brickwork joints then virtually any clay will do but, if you want super neat brickwork then the mix is more important.
Good ideas Fox, I got some of the fire cement in a tube myself mainly to set the bench so it’d have a seal between pieces. Just finished at 0300 even with feeling crummy most of the week and the frustration including lack of communication from the guy selling cores. Gotta get back on the road today, hopefully later morning, but the family has a RMH for main heat for the winter in the new sort of finished icf house! Lol
Thanks, hopefully we’ll be moving in around the day before Thanksgiving. Still need the driveway gráveles, earth moved around the house, electric brought in and sewer ran out to the lagoon which needs built, plus water ran inside and black pipe for the stove… supposed to all get done this week!
Also I need to teach the wife and kids how to light the RMH. My buddy was super impressed with how well it draws, even cold. Looking forward to teaching and being able to play more with it in a few days.
Maybe an odd question for you Thomas, or anyone else if they know… due to finances, the ceiling is dry walled, but don’t really have the money to blow in insulation right now. With the insulated slab, ICF walls, and if we burn the RMH every day or two, do you think the house may stay reasonably comfortable with the un insulated attic? Sounds like that May run another $1-2k that I really don’t have right now, since I am catching up on paying for dirt work, water and sewer, etc.
I wasn’t sure how much (hopefully less) heat loss with radiant heat versus convective through the ceiling which is just trusses and drywall for now.
My answer is yes. I think you can heat it for a while with the attic uninsulated.
You can burn that rocket all day long if you like depending on the weather.
If you still feel cold cover the attic floor with old blankets and plastic over that.
Old blankets and plastic? Good tips, I’m sure we should have some of that house wrap that goes under the siding, not sure how many old blankets… have to ask the wife. The center third (great room/dining area/kitchen) that has the vaulted ceiling has insulation batts around that, along with strips of the wrap covering cracks that I saw the Amish had used so insulation wouldn’t filter down through them. I’d assume that helps some, too.
If needed will start with over bedrooms, and leave the pantry for last since we want that to stay cooler. Thanks again, Thomas. I’ll look forward to posting our experiences with this heater over the winter… also, if I can help any of the Amish build one at their place, one sounds interested in one for his shop but not sure about the main house until he really sees ours in action!