Building RMH in NH

[mannytheseacow]

That's looking great, Ray! I like the bigger opening of the 8" systems. I wish I could facilitate a system that size. I noticed a lot of ash in my first couple of burns too, but like you I was burning some punky wood with some bark left on. By comparison, though, the ash was no where near what my traditional wood stove produced.

Good Work! I'm excited to see your progress throughout your build!

[matt walker]

Ray, it sounds to me like you may be burning wood with a high moisture content. These things are really sensitive to the MC of the fuel. It's really important for regular use to have well seasoned wood, just like any wood stove. You also are probably still pulling some moisture out of the walls of the firebox, and the non insulated riser is not allowing the burn to continue into the riser which will go a long ways towards keeping overall temps high and smoke down. But yeah, depending on fuel type and MC you will see varying degrees of ash. That's one of the largest variables, different wood types and MC can completely change the character of a stove. Keep playing with it, you'll learn what works for you in that stove and what doesn't.

[rjdudley]

Let me say at the outset of this post how grateful I am that both of you, Matt and Manny, reply to my posts. I have been sooooooo hesitant to build this heater due to plain fear of screwing this up.
I bought Ianto's book last year and have read it twice. I've been to other "permaculture" websites that discuss these, I've seen the videos on youtube and YET there's been something that really sort of scared me. And I think it was the feeling that even though others have built these I had this feeling of being alone going forward. You know, no ones brain to pick, no one to ask questions of, etc.
So reading your posts and getting replies to my posts has been monumental in moving me forward. Thanks again.
Now, Matt, I think you're correct about the moisture issue. Several pieces I had put to burn had pitch/sap boiling out the end of them during the burn. AND, the stack isn't insulated AND, like you, I believe the chamber isn't fully cured. Good call.
Manny, what can I say. My wife and I have look and re-looked at the great photos of your build. We've enlarged them to check every nuance we could just to glean as much as we could. Keep it up, I'm learning a lot.
Ray

[mannytheseacow]

That's awesome Ray! I'm really stoked to be part of the community here. I've learned so much from everyone here and I'm glad I have something that someone else is learning from.

I first started hearing about RMHs several years ago but they seemed sketchy. All the progress that has taken place in recent years by all these great people has made them much more doable, though it wasn't until I started seeing Matt's videos that I was like "okay, this is something I can do and I won't burn my house down".

I'm really motivated by seeing your progress, too!

[matt walker]

Yeah guys, I've been in the same boat. If you go back to my first posts in my "Home" RMH build, you can see I had as much or more trepidation. I'm as glad for this place and our nice spirit of community as anyone, and all deserve to share the credit for that. It is so cool to see your builds, if I were closer I'd be right there mixing mud with you.

[rjdudley]

Ok, so now I have a new issue.
I didn't make my mold completely flat on top and so now I'm going to have to grind/sand that refractory cement on top so I can place my stack. Right now it's very wavy and uneven. Think that stuff grinds down alright?
I'm also going to have a bit of overhang since my burn chamber is only two inches thick vs your cob 4 inch thickness. The 8" pipe should fit fine but the 14" will be overhanging a bit. Guess this is where we put cob to work?
I have to say that I'm loving that refractory, no shrinkage, tremendous insulating value. I can keep my hand right on top of it while it's burning and it barely feels warm.
If I use it in my stack I think I'll find the same result which should provide for great burns.
Ray

[matt walker]

Ray, you could also build up a little flat landing for the riser with either cob or just fireclay, then do the same for the barrel landing so the heights are correct. You should only have to gain an inch or two, and yep, form that riser landing and transition with cob. You'll be just fine.

That refractory is great stuff, I have to have it trucked in since I'm 3+ hours away from any supplier, but it sure is nice to work with.

[rjdudley]

I know the feeling about having it trucked in. We had to make a decision as to whether or not to have it shipped to us. We decided that since my wife was on vacation we'd use the time as a sort of "day date" and we drove 4 hours each way (8 round trip, not including stopping for lunch). It would have cost about $85 to have it shipped (BTW we paid $62 for each 55# bag). A little expensive, but, if we ever have to do it again we'll have it shipped.
Ray

[rjdudley]

Ok, so it's finally stopped raining here in NH and I wanted to get another crack at getting a good burn in the chamber. Here are the results. I tried to use drier wood (from wood pallets) and I wanted to really get it hot. Check out the photos:








So, uh, yeah I've got some questions. Does these look like anything anyone here expected to see? Is this normal and that's why we use cob to surround it? Does anyone think it's still safe to put in the house? Do I need to re-pour a new one?
Anyone? Matt? Manny?
Thanks
Ray

[matt walker]

It looks totally normal Ray, actually you did a great job pouring it. There are very few voids. The Hardiboard is going to come out of there, that's normal. It's a temporary mold at best. As for the wood charring, yep, these things are incredibly hot and even with insulating refractory it's going to pass on that heat eventually. And yep, that's why we wrap it with cob and why it's a "core" and not a "stove." It looks perfect man, one of the best I've seen. Don't sweat it, just plan to encapsulate it completely in cob. You'll want insulated cob, or clay/sand/perlite, all around that burn chamber to as thick as you can get it. Then the whole thing can be wrapped in regular cob or whatever you are intending to use as finish. Manny's brick enclosure is really nice in my opinion.