Ronald McLaughing

Ok. In a few weeks it's probably time to rebuild the burn section of this stove. I have studied ianto evans book a little bit and contemplated a bit about the situation here.

We have a system of 4 23/32 inch heat transfer tubing over 31 ft long with four 90 degree bends, two of them probably very turbulatory (is that a word?, you know what i mean though...). Ideally, from a functional standpoint, we should dig up the heat transfer tubing and replace it with 8", but the work and cost of doing that leads me into the following idea:

First, scaling down the 8" example from ianto's book. Even though we have a 4 23/32 inch (120mm) heat transfer system in place, to be a bit safer because couplings can possibly have bit smaller cross-section area and so forth, build as if it were 4 21/64 inch (110 mm). That means almost halfing the sizes of the example of the book.

The burn tunnel would be fire brick, 90x90 mm (3 35/64 x 3 35/64 inch), the heat riser slightly bigger along with the rest of the cross section areas which are important. However, the book says that the taller the heat riser, the more drag. So my idea is to make the heat riser as tall as possible to create enough force to push through the hundreds of miles of duct pipes. How tall can I make it without creating other problems?

Also, The barrel would be a standard 55 gallon so there is plenty of space for insulation around the new fire brick heat riser. Could that cause any functional problems?

Furthermore, from any people having experience with any kind of similar build, would you tweak the dimensions of the feed tube and burn tunnel lengths otherwise than scaling it from ianto's 8" to 4 21/64" ?

Thanks.

Hey all.

Thank you so much for the reflections and explanations on this.

It seems to be a necessity to rebuild the whole head of this dragon. Maybe we will get time to do this during the coming spring. I will update this thread when we reach the next step.


Thanks for your time

/Ronald

Hi. I am new here, and want to share the project I and a friend has going on. It is primarily experimental but intended to be used to heat a specific indoor area in the future. The build is not complete, but complete enough for testing.

The material we built it with is as follows: Common bricks for the outer shell , vermiculite as insulation, fireproof brick for the feed/fire chamber, stainless steel tube for burn tunnel and inside of heat riser, vermiculite/clay mixture forr heat riser insulation with refractory mortar as a rounded top layer. Stainless steel tube the first two meters in the actual heat mass, the rest is galvanized duct tubing. The actual heat mass and mortar for the bricks consists of clay from the nearby ground, sand and water apart from several big rocks to reduce the amount of mixing needed. The end of the duct piping concists of insulated duct pipe going 4 meters up and through the wall.

We still have about 10 cm of heat mass we still need to put on the top of the heat bed and the final cosmetic plastering and so forth is still to be done. That's where we are at now.

While we built the construction we put the ducts together and insulated the with mineral wool just to try it out. It worked pretty good and I remember we could, after some trixing and smoking-in incidents, have the fire going for hours and hours.

The session we had after that we put in the heat storage material around the duct pipes, waited for a couple of months for it to dry a bit before we decided to test it out thoroughly. We have a construction with an access door used both for cleaning/inspection and priming. After priming with some wooden sticks and paper there we get the mass heater going pretty good. It's not doing any intense rocket sounds o anything but burns calmly and stable. But, after 20-30 minutes approximately it starts to smoke in. There is no way of getting the stove to burn in the right direction again without priming again in the priming chamber.

I really would like some experienced RMH bulders ideas of why that is and how it might be fixed. Below follows a diagram with measurements and some photos.











I held the camera in the chamber after the heat riser pointing back. what you see is the lower part of the heat riser and the inside of the barrel.