David Von Mills

I couldn't find a specific thread for this topic so i will just post here. Does anyone have experience with metal roofing suffering from the RMH exhaust? 16 years with a woodstove and i didn't notice this. Not even halfway through my first year with the RMH and i'm noticing rusting of screwheads and the metal roof being impacted around the chimney exit. Any input would be highly appreciated.

Thomas-you earned the kudos-you're welcome! I checked your link to Paul's 7" batchbox and i'm glad to see my old (new!) door off the streets and out of trouble. I am in the (slow) process of cleaning the stone front of the stove but when i am through i will snap a few pics and upload. Thanks again for everything Thomas!

I am in the first winter using my RMH. I had a Woodstock soapstone woodstove for the previous 16 years i lived in my house. This house is 900 sq.ft. I averaged about 2&1/2 cords /year over that time. I am carefully measuring my wood usage this year and, so far, it looks like i will be using appx. 1&1/4-1&1/2 cords for a rather mild (so far) winter for my area of south-central Colorado (San Luis Valley). My build is a 7" system using clay and stone. My house is warm and i love the look of the stone in my living room. I also cook most of my meals on top of the barrel-something i could not do on the soapstone stove-BONUS! That being said, my main motivation for partaking in this endeavor was the reputed lack of creosote build-up in the chimney pipe and i have yet to know as i will check at the end of burning season. The reason this was my main motivation was that i had to get up on my roof every year to clean the chimney and a few years ago i was up there and the wind blew my ladder over and i had to jump off the roof. At 50 years old that wasn't too big of an issue. I'm now 63 with two wrecked knees (took my football a bit too serious back in the day) and i can see myself blowing a hip if i have to do that again. So, if the creosote issue is not a real problem then the only issue left is what i see happening to my metal roof. Whatever is coming out of the chimney seems to be degrading the painted metal and rusting the screws adjacent to the pipe. I'm not sure but i think this would be mostly water vaper due to the high temperatures of the burn. I'm wondering if this vapor is acidic in any way. Any thoughts or suggestions would be greatly appreciated! By the way-i want to give a huge shout out to Thomas Rubino at Dragon tech for his generosity and technical advice-just a stellar dude.

Thank you again Gerry for your reply. I don't remember where i heard that info either-but i did hear it. I believe the theory is that if you create an exhaust path that goes from hot to cooler back to warmer (combustion core/riser-exposed uninsulated barrel-insulated manifold) that there could be a sort of thermo-lock that could back up smoke into the combustion unit. I personally do not know this to be true but i guess that is why i'm here-to learn from those that know more than i. If no one else has heard of a problem with an insulated half-barrel manifold then i would love to insulate it as i have the ceramic fiber blanket material (2" thick) and that would take care of my expansion joint issue! Thank you for the info-take the best of care.

Thank you Gerry for your reply. I intend to use ceramic fiber blanket material around the combustion core/riser but i have heard that it is not wise to use this around the barrel manifold so as not to offset the thermodynamics of the exhaust path. I am open to new info if available and welcome this if you can share.

As Glenn stated in the post below yours, these were just clay blobs to see if the clay would be useable for the mass infill part of the stove. I will pour my own refractory cement combustion core and riser. I will also do a stone facing integrated with the mass infill and will also use stone as part of the infill. My question still remains-should i be concerned about the apparent alkali content of the clay-in particular around the barrel and stovepipe? Also Thomas, thank you very much for the advice concerning your pop-in door and secondary air channel!

Dear folks, I am getting set to build a rocket mass heater and i have a question about the clay. I made a couple of small test bricks to see if my earth is good for building and it looks promising-very sticky and is drying hard and strong. My issue is that, after forming the wet bricks and putting them on a plate to dry, i woke up the next morning to find what looked like two crystal-meth chia-pets! I am assuming this is alkali but i don't know if this is cause for concern when using this for the build. The bricks seem strong and solid but would there be any issues around the barrels and stovepipe? Any feedback is much appreciated. Thank you!