Newbie - Rocket Mass Heater Build

[Oddmar]

Hello, my name is Oddmar, and i'm an addict...lol.

OK, what i really mean to say is, i think i'm funny. At least i try to be funny, unlike all those politicians and rude frowning people.
BACKGROUND
I was born in Illinois (01-14-1969 Matt, just FYI). rode a bicycle across the United States (more like a loosely-formed group of independant countries), and quickly found out my fellow Ill-Annoy-ians to be kinda standoffish and rude compared to nicer people. In the last several years i began attending a Toyota 4x4 event in Texas, the Lonestar Toyota Jamboree. Folks down south are friendlier than people from Illinois. Also i found out that the 'Castle Doctrine' doesn't just apply to shooting at burglars, it means your home is your castle...Liberal dweebs move in next door and build a $300K home, landscaped yard, and they can't force you to clean up your yard...Double wide trailer, 7 dogs, 12 or 17 cars (haven't mowed the grass in awhile, not sure there might be 20 cars)...lol. I must be a redneck in a Yankee's body. Moving to Arkansas, even have the Driver's License to prove it.

So i've been reading about these rocket mass heaters for a year or so. Along with cob or straw-bale houses. I already have experience with underground houses, i met Mike Oehler in 1992. But i digress... A friend of mine is a retired Marine, living alone on 40 acres of land with no electricity. I planned to build him a stove a year back, a forced-air wood-furnace out of 1/4" plate steel i have laying in my driveway. Then i learn about RMH's. Intriguing design...burns ALL fuel, smoke, pyrolitic gases inside stove, uses 1/4 to 1/8 the wood of an efficient box stove, not too expensive to build. Only drawback is space required for thermal mass and labor building same. My friend is waiting for me to show him...along with all the other people i've talked to locally about RMH's.

Sounded great...last fall i built a proof-of-concept out of 5" duct inside 7" duct with vermiculite packed between...No outer drum, just the feed can (6" diameter coffee can), burn tunnel and riser, all round duct connected with 90° elbows...even though my burn tunnel was too long it worked pretty good, but got so hot the duct burned through/ became brittle in 4 or so firings. But it proved to me the thing would work if it was built right.

I read alot. Online lately, but my room is ringed with paperback novels. Mostly sci-fi and fiction...the dreams our stuff is made of. I read 'The Mad Scientist's Club of Mammoth Falls' series of teen novels when i was young and it permanently warped me. So i haven't bought the 'Rocket Mass Heater' book but i've read alot of forum posts and i try to learn from other's sucesses. Leading me here, asking questions of Matt Walker after re-re-reading his 'Rocket Mass Heater for my home' thread. He suggested i start a new thread detailing my build of his design.

BTW, Matt, I came up with a Rocket Mass Barbecue idea a couple weeks ago...then i saw today you built it. The Force is strong with you... The bench idea is neat, i might build in a bypass valve to keep the bench cool in the summer when i want to barbecue without using ANY store-bought charcoal or propane...Yay!

You said yer not getting any smoke up top because the RMH has burned it all up...i was gonna use lava rock between two grills (expanded metal) inside a section of drum with a Weber grill lid on top...the hot heat riser gases will strike the lava rock, it becomes hot, radiant heat cooks the steak/ meat...juices drip on the hot lava rock and instant smoke flavoring...

I intended to put standoff legs on my barbecue drum but the hot gases hitting the lava rock and flowing down inside the outer drum will work better. But i'll build myself a barbecue RMH later, after i complete my move to Arkansas. For now i need to get Matt's RMH design built for my friend up here in Illinois. I'm off...y'all prolly figured that out already...lol...to cut wood, mix and cast refractory. Pics n words to follow...

[matt walker]

Oddmar, welcome. Thanks so much for the intro and thread, I'm really excited that you will share your build with us.

Great ideas on the BBQ! The drippings on lava rock is brilliant.

Looking forward to the build!

[Lollykoko]

Hello, Oddmar! I'm the mother figure waving at you from the eastern horizon (you are less than a year older than my son).

Lava rock in the top of a rocket heater for grilling purposes? I'll be thinking about how this might become part of my outdoor kitchen.

[Oddmar]

Hey there Lolly. I've got some new ideas you might want to peruse before designing an outdoor cooker. BTW, everyone, feel free to save/ use any of my pics/ illustrations I post on here. If i don't want people to use my designs i shouldn't post them on a public forum, right?

I'm just a bit cash poor right now so i haven't bought the vermiculite i think i will need. Contemplating building my friend a rocket mass barbecue first to get the hang of it, outdoors will be more forgiving than an indoor experiment.

Matt has re-re-re-rebuilt his outdoor barbecue into a fairly attractive ceramic-glass-sided box stove. Gone is the super-high-temperature burn tunnel that ensures all the fuel is burnt. I really like his design of the viewing port/ oven chamber with the cast-iron skillet above as a hot plate. I simply must have that feature in the outside barbecue. That will still allow viewing the fire while sitting at the bench. And with temperatures here in central Illinois already hitting 95°+F, i've been dreading the thought of baking next to a hot radiating drum. So I've been obsessed the past two days with getting rid of the hot metal surfaces for summer use, while still having them available for winter use.

I've come up with a few modifications to draw cool air into the bench for summer enjoyment.

I also love how efficient a true RMH is. I have been avoiding the Weber grill the past year because it consumes charcoal quickly, and you may have noticed how the price went up but the 20# bags turned into 16# bags. Propane grills are overpriced for what you get, and I haven't been able to justify spending cash on a burner bar/ regulator/ steel to build one in the shop.

Here are a few illustrations I've created to share my designs.

[matt walker]

Whoah, Oddmar, awesome! That idea of powering a cold air draw with the hot exhaust is just great! This is so cool.

[Lollykoko]

Interesting sketches. I'll be chatting about this with friends, very soon.

[Oddmar]

I only had a half-bag of vermiculite left, and didn't want to start mixing up a burn tunnel batch only to find out i didn't have enough.

So back when i started this thread, i drove all over before finding the right "Fire Clay". I bought (2) 50# bags for $42. The same day i looked for Vermiculite but Menard's was out of it and no one else knew what i was talking about.

Today (June 8th) i called the local Menards and they had just gotten 14 bags in. I went out and bought a bag (3 CU FT) for $16.07. (Leaving me with $3.50 in change. Oh well, when a customer picks up some magnetic signs i'll have $$)

The Aprovecho Research Center describes making rocket-stove firebricks from 85% Vermiculite and 15% Fire Clay so i'll try that mix tonight. Wish me luck. http://www.bioenergylists.org/stovesdoc ... stove.html

[matt walker]

I've been wondering about your progress, glad to hear you are still on track. I think casting your own insulated firebricks is a great way to go, with one caveat. The bricks severely limit the shape of your stove, so work out the dimensions and any custom shapes before you cast 'em, so you can build what you are picturing.

I am glad you are going this direction. I've found the typical firebrick that most folks use really hurt the performance of the stove, and the rigid shapes lead to less than ideal burn structures. Good luck, and keep us posted!

[Oddmar]

I think you misunderstood me.

Aprovecho cast individual firebricks for their stoves. I'll be using the same mix as they did but casting the burn tunnel, and then separately the heat riser, in one piece as you did for your house RMH.

But yeah i'll still have to design any features i want into the interior mold. Such as the Peterburg tripwire and 'turbulator' deflector at the bottom of the heat riser.

[matt walker]

Ah, right, the mix, not the bricks. Got it. Can't wait to see what you come up with.