6" to 8" Conversion at the seacow

[mannytheseacow]

[Oddmar]

Wrists are fine. The other day we stopped at the local Sears and picked up a small trailer-load of pallets.

When i had the RMH down the hill in my cabin i was burning mostly scrap lumber. Nothing bigger than 2x2. Minimal smoke and ash, a ton of heat. When i rebuilt it up in the new shop, it has been producing alot of ash and smoke, and not getting as hot as when it was down the hill.

Glen has been feeding it with deadwood from the property, splitting it and burning it right away, no drying time. He rarely splits the wood finer than the thickness of a closed fist. And he cuts it long. So before it can burn through and fall down flame is creeping up out of the feed and smoking up the room. I CANNOT convince him he is doing it wrong.

The pallet wood is nice and dry, and thin enough it falls down properly. It is burning ALOT hotter and is overheating the shop even with minimal insulation and 12' ceilings. No splitting required, i just have to knock the boards apart with my BFH. He cuts them to length with my miter saw.

I will be glad when i can afford to move into my own place. No one to argue with but myself.

[ByronC]

Manny, I've been admiring the brickwork of your RMH. Very nice indeed, and I'm going that route for my RMH also. I'm courious to know what you did for insulation under the bench, i.e. to keep from heating its foundation or whatever is directly below it?

[mannytheseacow]

Hi Byron,

I might be inclined to say go with the 8" if you can, though I've only built 6"s....

I didn't do anything under my bench. It's coupled directly to the floor. I don't know if this sucks heat into the slab or makes no difference? Curious what other's think. I just posted to Adam this morning that the brick seems to be highly insulative compared to rock or cob. Rock might be a better route if you have access to it. I seem to recall that you might have some limestone down there, and maybe some schist. Schist might be worse than brink.... depends on your specific setup, I guess.

[ByronC]

Hi Manny,

I've been following the MHA guys for some 15 years, and studying their masonry heater construction projects in detail. You know, those BIG beautiful Russian heaters and contraflow fireplace style heaters with glass fire viewing doors, constructed of dense firebrick cores and then standard brick for the skins, or faced with stone. Really cool stuff, but way to labor intensive for my kind of DIY heater project.

Yeah, building an RMH directly on a concrete slab will suck some heat out of it for sure, though on a large RMH there is possibly the benefit of added thermal mass. Most RMH construction plans and documented projects I've seen, and that's not a lot by any means, where the heater is built directly on a concrete slab, will include either an air gap or several inches of insulation between the RMH and slab, to help the bench heat up quickly and retain its warmth longer.

[mannytheseacow]

Not sure to post this here or in the hangout. I helped a friend demo a house this weekend and salvaged the HVAC from it.

Behold my craigslist score of the week: 60' of 8" duct along with elbows and misc. bits. Way more than enough for the conversion; I'm picturing an outsider lounge in my future.

[Lollykoko]

What a great haul! An outside lounge area would increase the time you could spend outdoors quite a bit in the transition seasons, Manny. Sounds like a winner to me.

[matt walker]

Dang, that is a fantastic score! Nice work man. It's amazing how much having heat outside changes things. I fired up my outdoor system yesterday for the first time since November and smoked a shoulder for pulled pork. It was so nice hanging out out there. Outside heated seating area should be at the top of the list.

[mannytheseacow]

I've been putting this off for a long time and I went out today to pick up the last of the materials I need to buy to do this project. The mold has been staring at me since March and I know that once I start there will be no stopping until it's done.

I got home after the long trip and I'm looking at it and I wonder, "just what am I getting myself into here?" So I take a pick and take a couple swings. Seriously, in no more than 15 minutes I'm down to the heat tubes in the bench. The barrel is off, the riser is down, the water tubes are out. It's like, "Oh yeah, this thing is just made of dirt and rocks."



Part of me really wants to try the water again, this time just a tight coil heat exchanger wrapped around the exhaust just after it comes out of the plenum. Part of me just wants to tear this thing out, get the 8-incher in, and get the mess cleaned up.

I'm really astonished by how well the heat riser has held up. I can totally salvage it and use it on another 6" stove.

One last goal of this project- the bench has always been fantastic to sit on and warm my bones, but honestly- it's not that comfortable. Anyone know anything about chair design?

[pa_friendly_guy]

For forming the cobb to feel more comfortable to your behind why don't to try sitting on hard wooden or metal benches. Select a bench that is really comfortable for you and make a template of the curve out of paper or cardboard. As an example my church has hard wooden pews that are very comfortable, so just check around town and see what you like. Then cut your self a wooden tool out of plywood with that shape and use it as a drag across the clay to mold it into shape. That would be ok for sitting, if you want to lay down I would get some cushions from an old couch, it turns out people put out old couches all the time that are free for the taking. Just cover them with a blanket or something of that sort and it will look like everything matches. The cushions would slow the heat gain to the room a bit at 1st, but it should level out in time and work OK.