Rocket Mass Heater for my home

[thickstrings]

Matt , Cool! Are you going to put the angled trough in the fire box floor? Your riser goes to the floor, right? I am still not clear on what advantage the glass top will give, other than viewing. I have seen the thing that P berg made with the sheet of glass over the top....unique...I wonder about durability in everyday use. Any air channels other than the P channel?

[matt walker]

Wiley, you can come eat bread with me anytime. I promise I'll bake it with a rocket, maybe before you wake up. Just ask Manny!

TS, I probably won't put the bevel in the fire box floor. I have a little ash shovel that fits the flat floor perfectly, so I'll leave it flat to facilitate cleaning. The glass should hold up just fine, it's in a much cooler location than in my outdoor fire box. I think Manny is referring to the trouble folks have spanning the firebox ceiling when building with brick. I've never had a problem when casting them, but the glass on top allows easy fuel monitoring and is pretty cool to look at. Yep, got the idea in Montana. The boys and I were hanging around the mock up Peter and I built outdoors late one night, drinking some adult beverages. Peter had gone to bed, and you know what they say about the cat and the mice. We found E&E's demo glass and put it on there in a stroke of, uh, inspiration! Yeah, that's it. Anyway, it is a cool deal. Air will be standard for Peter's design, 20% of CSA primary and 5% P-channel. Oh, riser goes to the firebox floor, not the room floor. Overall riser height is around 42" or so, which should be fine. I'm a little concerned about the top gap being too tight, but we'll see. I can't remember what I did there, and no doubt it's changed with ash build up and barrel deflection. I expect to have the barrel off at some point in this conversion, although I wouldn't complain if that doesn't need to happen. I'm using 6" measurements even though my ducting is 8". Don't copy this size mismatch, I'm just working with what I have and accepting the flaws.

[mannytheseacow]

The misses was just saying the other day that we never did have any of that bread....

Next thread derailment- I'd like to see more about how you join the glass in. I remember asking about it once but can't find the answer. I think maybe you said you use that fireproof rope, but maybe I imagined that.

It seems like this would be a good opportunity to show some photos of how you do that. Also, I'd like to see more details about how you formed the port and p-channel in. And since you're taking orders, I'd like a ham on rye, too.

[mannytheseacow]

Oh, and yet another thread derailment.... I didn't notice until you posted the demo photos, Matt, but dang your feed was super deep! What led to that? I might try that to keep this dense hardwood from smoking back during long hot burns.

So that deeper feed is just cob, right? You didn't cast your feed that deep?

[matt walker]

Crap, I know! We totally forgot to eat that bread, or I forgot to offer it. Sorry man, I was having such a good time talking and showing you around....oops.

Too late on the window, the thing is on fire behind me right now. I got going with the door and p-channel fabrication and next thing you know I was all muddy and then it was on fire. Windows are easy, just place them against an opening that is a little smaller than they are. Maybe use some fiberglass rope or tape on the core side, but just let it set against the core, don't capture it. Then I cob it in, overlapping about an inch or so all around. If you have fancy materials you can use ceramic board insulation to hold it against the core, but in this case I just used cob.

Yep, the feed was cast 12" deep as usual, then I built up that surround with insulating cob. I think it just grew as I was patching it, I don't think it was intentional. Worked really well though.

Forming the port is just a small box glued on to the bigger firebox mold, you can see it in one of those pics I posted above. I usually cut the hole for the p-channel after I cast the core, using masonry drill bits and a cold chisel. Kinda sketchy, but I found trying to cast a hole for the channel was more of a pain than just bashing one in afterwards.

[wileythenord]

What are you using for glass? Any experience with Mica? I was searching for refractory cement and a guy on permies.com put up a thread a million years ago about sources, which led me to amazon, which led me to this:


I'm not doing anything exotic like viewing windows for a while, but it seemed interesting to me.

[matt walker]

Mica is interesting, but only available/affordable in small pieces. I'm using ceramic glass which you can find on ebay as stove replacement glass. Not terribly expensive, and available in any size you want.

[matt walker]

Got a run in with the Testo before I left for the workshop in New Hampshire. It's stable, and pretty good on CO considering things were still drying out and will most likely improve. It's a small load of wood, so the time of peak burn is shorter than it would be if I stuffed it, but man, this thing puts the barrel right up to max temps so I'm thinking I'll probably be running half loads all the time. This is about 6 pounds of mixed hard and soft wood, CO is just under 20ppm at peak burn and stable there until the fuel starts coaling. Not a bad early run....

[matt walker]

Okay, I'm thinking I'm going to tear into my bench and add two barrel halves which will extend the long side by 68" or so. I'm having a hard time getting motivated to destroy the thing when it's ready for winter, but.....here goes. Oh man, I'm gonna make a dusty mess of my living space. Ugh.

Now that I've posted it, I've got to do it, right?

[pa_friendly_guy]

Right !!!