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Building our Rocket  RSS feed

 
lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
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Hi all,
Discovered permies.com whilst getting back up to speed with RMH's. We dismantled our half-built one in 2009 and then ran off to sea. Five years later, we're back in northern france and are rebuilding. Living in the tropics (on a junk rigged boat) where a swimsuit feels like too many clothes, I am now feeling the COLD ;o) Paul's DVD's were brilliant I can recommend them!!! They helped fire me and the old man up again to dig up the clay, and trash the kitchen.

It was inevitable that having discovered this forum, we'd be drawn in to permaculture, and so, the rocket was put on back burner ;o) whilst we created hugelculture, mandala, and spiral herb beds. Also managed to lift the wooden kitchen floor, chipped out concrete under burn area, gathered the materials etc etc

All the spinning plates are beginning to fall into place now, and I thought it might be useful to document the rocket build, both for those that follow and in the hope that others more capable than me, could point out any errors in the build.

The rocket is (to be) as per Evans and Jackson, with Peter de Berg's 'ski slope', 'trip wire' and feed box plate. It's an 8" (20cm) system. 55gal drum, old water heater to retain insulation, and perlite vermiculite mix insulation under burn box. We've changed from standard bricks to good quality refractory brick for roof of burn chamber, and to second grade refractory brick for the chimney. Also now substituting refractory cement for the mortar.

In figuring out how to grind the trip wire into the roof, I've used refractory mastic to glue three bricks together side by side (twice) I tried to use refractory cement but couldn't get it thin enough because of the grog size. (If I remember rightly Grog is added to clay to increase resistant to thermal shock)

My biggest 'worry' is compression of the 4" of insulation under the mass. i have asked on another forum and had some replies, but not a definitive 'this is what you do in practice'. Surely I can't be the only one who doesn't want to lose heat through the concrete floor? So far I seem to be.

oK, this whole excercise hinges on me being able to upload photos. i'll try as attachments and see if that works!

Any encouragement and advice would be appreciated.

Lesley


 
Glenn Herbert
gardener
Posts: 2193
Location: Upstate NY, zone 5
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Sounds like a good plan so far
I am not clear on the function you have planned for the old water heater, though. What sort of mass are you thinking of?

For insulation under the burn tunnel, you can't beat lightweight insulating firebrick, but it is quite expensive to buy new. A mix of perlite and fireclay (with just enough clay to bind the perlite) will do fine and be cheap and easy. It is not compressible without a *lot* of weight, once it is packed and dried. Also, it will help to make a raised deck to work from, with bricks spaced out and supporting a layer of cement board. This will allow air to circulate under the hot zone and carry away excess heat.
 
lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
3
bee chicken food preservation forest garden hugelkultur solar
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Hi Glenn,
Many thanks for your reply. I'll try again now to post pics of what I've done so far:
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lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
3
bee chicken food preservation forest garden hugelkultur solar
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I left the red brick on the far left loose, so I could lay out the next two courses and make an adjustment to its position. I wasn't sure how wide the mortar joins would be.
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lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
3
bee chicken food preservation forest garden hugelkultur solar
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The red bricks laid flat are mortared in, the verticals and two sets of 3 reds for the 'roof' aren't yet. I used refractory mastic to glue the Reds together, as I'm finding it difficult to get thin mortar joins using refractory mortar. It's a joy to work with the mastic, the mortar is a pain. I am tempted to use it for the riser. Anybody reading this have any experience with this goop? It's rated to 1000°C and is for fitting and repairing 'heating appliances', fireplaces in refractory brick, and for repairing woodburners. It sticks like s**t to a blanket, especially on vertical surfaces. (Unlike the bl@@dy mortar)

(The white fabric at the back is an old sheet to keep the clay damp whilst I re-lay the wood floor. (Kitchen Floor ;o) the wood will end about 1.5m from the burn chamber, and we plan to tile the rest of the floor, for safety and ease of cleaning.

The right hand set of three reds: I plan to grind everything to the left of the pencil line with an angle grinder, to a depth of about 1cm, then, grind the exposed 'arrow' so it slopes back. (It will then be placed so the arrow is inside the chamber, pointing towards the riser) this, and the ski slope (which I need to modify slightly having re-read the instructions) are both Peter de Berg's modifications to cause turbulence of the gases in the chamber.

Now to Glenn's questions:
The water heater has had its top and bottom removed and it will go around the brick riser to hold in the insulation.
The mass, a 4.5m long bench, will be made of clay/sand mix with granite rocks, housing a double run of 8"conduit. Stainless steel nearest the burn, aluminium further away. It's the compression of the insulation beneath that bench, that was causing me concern, but I am a bit more optimistic after hearing your comments!
You said "with bricks spaced out and supporting a layer of cement board" What do you mean by 'cement board'?! I guess I should google it? We have some old concrete rabbit hutches, that we'd planned to dismantle, the roof pieces are about the right width and about 1.5cm thick wonder if they would do the job? This is for the bench not the burn chamber, so the temperature would be lower.

We are very fortunate to have 45% clay on-site, and my other half is digging out the foundations for a bread oven, in finding me clay for the rocket! This part of Normandy is a granite area, so we have a pile of the stuff pulled out of the garden over a ten year period (before our no-till conversion) We're recycling sand that was under the liner of a pond our tenants dug whilst we've been away. The pond is now full of logs, and is destined to be a hugelculture bed.

Ok it's late, the mouse is caught (sorry, my permaculture attitude does not extend to willingly sharing the house with a mouse) and I can now head for bed. Should have the floor finished as far as I can tomorrow then we can refit the kitchen sink and when that's done, I can get back to the rocket. Next update at the weekend, if all goes to plan.

Bye for now folks
Lesley
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6. Riser end of burn box, ski slope
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7. Roof of chamber
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8. Layout
 
lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
3
bee chicken food preservation forest garden hugelkultur solar
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Saturday update.

Wood floor is now down and kitchen more organised. Have shelved the reply Bing of sink in order to move the rocket forward, as it's getting colder here!

Have been spending quite a lot of time in the forum, gleaning wisdom, and am now a bit concerned that we don't have an air space under the insulation on our concrete floor. Plus, I've decided to take out the red house bricks and replace them with firebricks, to reduce differences in expansion. i also have as many questions as answers, so am posting these as separate threads, to make it easier for those that follow.

And if that wasn't enough, We saw this:


So husband has the jack hammer out again as we're incorporating a hot plate and oven into the design.
Pics to follow

Lesley

 
lesley verbrugge
Posts: 44
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
3
bee chicken food preservation forest garden hugelkultur solar
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... Just found an E & E workshop video so now, out goes the ash pit under the feed tube, which means I 'll be back down to the foundations and can install the air tubes. Every cloud has a silver lining? So, tomorrow is demolition Sunday then, good to know.

Lesley

The 'reply bing' ? Should have read 're-plumbing' don't you just love to hate the autocorrect?
 
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