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Honestly......how easy is it to build an RMH?  RSS feed

 
Posts: 78
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I guess this question is directed mainly at those who have built one (or more) already.

How simple is it to build one?  Can I just buy the Ernie & Erica package and take one of their plans step-by-step and come out with a good working heater?

So this ideal case I'm picturing.......I buy some plans and maybe a book, I look through the plans and cut sheets / materials lists, get a general idea.  Do a few minor calculations if necessary, laid out clearly in the plans/book.  I get the stuff.  Then I bring in some strong friends to do the heavy stuff and we build, cut, pour, nail, etc. like we know what we're doing (because it's all there in the plans).  Then after a few good days' work, I throw some flammable stuff in the burn chamber (following the procedures laid out in the guide) and get ROCKETY FIRE, MAN!

So.........is it that simple?


Follow-up questions........:

How detailed are the plans?  Is anything "assumed" to be known but not stated (I guess they'd at least mention "if you don't know X, go study / try that first"?)

How much "customizing" might have to be done to fit a particular home / shape / heat output / etc.??

What skills are necessary to have to build one?  (I'm not against importing necessary skills via finding other people........most of my construction skills are minimal.)

What other things are assumed as part of building one.....anything important for a total NEWB, not only to RMH construction but to carpentry/construction in general?

Y'see, I don't need another new hobby.  I would like a better/cheaper heat source though.  I was sort of intimidated (though intrigued) by all the cool stuff I read / watch about RMHs, and want one........but with my situation right now I can't just dive into it all, then spend months figuring things out, adjusting, rebuilding, tweaking......... arrg!  I'm the chronically curious type that likes to know how it all works and get my hands in it all.  Frankly, at this point, I'd rather not do that for a new heat source.

(Aside, I had that mentality this fall, so I gave in to the friend trying to sell me a nearly new heat pump system for a great discount, and had someone else put it in.  Wash my hands of it, not go study heat pumps in all my spare time to get it going just right......that was the idea.  Then there were a few issues, then the installer had a trip or something, then cars broke down, etc, and he's doing this by moonlight.  Etc. etc.  So now I got into heat pumps and........... want to avoid that about rmhs, I just have too much else to do.  Phew.  OK, thank you for listening.)

TIA!
C


PS - in case it matters - this would be going in a 20-yr-old double-wide manufactured home with known thermal performance.  So I was interested in the pebble-style heater in the 2nd dvd.  I skimmed through that and it inspired me!  But detailed instructions for a newb, it wasn't exactly.
 
Posts: 167
Location: New Hampshire
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If all you want is one working one, then it isn't bad. Yes, get the book and read it well. At this point every RMH is custom although some folks are working on fixing that. But I would expect to need a couple days of experimenting with the core before being ready to install it inside.

But you do need to have the skills and tools to be able to install a chimney and cut metal. The chimney part isn't tough, and Home Despot has all the parts you need. Fitting the barrel and making the manifold are probably the hardest parts, and they are almost purely common sense deals.
 
Posts: 217
Location: US, East Tennessee, north of Knoxville
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Paul is heating his double-wide with a pebble-style RMH and measuring wood usage, details in this thread (link below). There are some nice photos on his stove and it'll give ya an idea of daily RMH life:

RMH heating through a winter on a half cord of wood
 
Posts: 114
Location: Nevada County, CA
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Ive yet to nail my RMH out in the boneyard (where firey mistakes are OK) mostly due to weather and time, but I would suggest doing an outside prototype of what you envision inside and testing it well before installation. Again, Im new to this too, but having tinkered with it and thought about it for a couple months, its a very good thing we didnt install it right away - mostly for the sake of the aforementioned customization required.
Very safe and reliable tech - when you do it right.
That being said - the Ianto Evans RMH book (and I assume at least as much of E&E's) is the textbook I refer to, and Ive yet to have one question it cant answer about RMH and the handful of rules and calculations required.

However, it hasnt made me a better retro-fit carpenter
 
gardener
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Location: latitude 47 N.W. montana zone 6A
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LOL;  It's so easy a cave man could do it (or you and your strong friends) ... Seriously, if you strictly follow the directions in Ernie & Erica's plans or book , you won't go wrong. On the core and riser the dimensions  MUST be right .  Make your transition area LARGE enough, and the rest will fall together.   As mentioned, build a test core outside ,make sure you use a clay mortar to seal it together, do not dry stack . Add a riser and let it roar. That will give you some confidence towards building indoors.   Some people are put off by making cob,  in truth you do not need that much of it and it is very easy and forgiving to make.  For me it was 3 parts sand to one part clay. I mixed them dry the added water to thicken. Nice thing about cob is, once you make it one time you can break it apart ,re hydrate and use it again and again.   Taking much more time and energy is;   Locating your materials (fire clay,reg clay, perlite, building sand), making sure your floor is strong enough , isolating your core heat from surrounding objects, (like the floor and walls) deciding where to exit your roof with the chimney. Burning the paint of of your barrel,  Buying all the food and drink for all your strong friends...  These things are all covered in the book (except maybe feeding your friends).... BUY the book ... READ the book ... if your still not quite sure then ASK HERE AT PERMIES  ! Somebody is always ready to offer advice.
 
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Location: Fennville MI
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I push paper for a living (until Wednesday 2/1/17, at which point I am retired!) and built an RMH from scratch without any plans.  I am, however, more handy than the average desk jockey.  It's a conglomeration of skill sets, but none of them need to be at a high level of competency   And having the Wisner's plans takes the guesswork aspect out of the process.
 
C Jones
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Thanks for the feedback, folks.  It's sounding like it might just be within my capabilities, assuming I give it some time. 

Appreciate the advice on building a prototype outside first.  And that every one is still at least kind of customized.  That validates my concern about this having to "become a hobby"....but then again everything is like that if you want to DIY.

Any other informed opinions out there for us slightly-intimidated newbies?
 
Posts: 47
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
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Hi C,

First thing is do NOT be intimidated! Just believe in yourselves, have good reasons for doing it, invest in some sound knowledge and get stuck in.

These are thoughts I wrote up after we completed ours in 2015 and are just my personal opinions!

1 If you have never built a RMH before, it could well take you longer than you think, to get it right, so if you want it for winter, start early. It'll take a while to dry and there's a lot of moisture given off. Much better with doors open. Don't ask how I know this.

2 Before you start, invest 18$ and download Ianto Evans book which is the bible for rockets. E &E's book wasn't available when we built, but we backed their Kickstarter and recommend their book too. It's money well-spent, considering the amount of graft and money you will put into the build.

3 Read 'rocket mass heaters' book/ Erica and Ernie's book from cover to cover and make notes in the margin so you can find the bit you need later.

4 Read Ianto's book and Erica and Ernie's book from cover to cover again, so you can understand the postings you'll find in this forum, and the questions you'll ask show that you have done some research and understand the basics.

5 By all means get fired up about the many rockets you'll see on YouTube, but build your first rocket using the measurements in one of 'The' Books, they work, they are safe.

6 Paul, Erica and Ernie have produced a set of DVD's Seriously consider investing in them. They explain a lot of the theory and they convinced my significant other that this was a GOOD IDEA. I was psyching up for the hard sell routine, but he said 'we 're rebuilding' before we finished the videos ;o) Plus they are fun.

7 Watch the videos on the permies site and E&E's website to get a better understanding of what you're contemplating doing.

8 Before you post a question in the forum, take the time to search  the forum. Others have probably asked your question. You'll learn a lot of information this way, and i got answers to questions I hadn't,t even thought of.

8 Bear in mind that not all of the the rocket designs on YouTube show you how they didn't work very well in the long term because of basic design flaws (because their builders hadn't read THE books?)

9 IMHO I reckon the chances are slim that you will build your rocket for 'nothing'. It is possible, if you are lucky enough to track down everything you need, but we decided that we,d have to dig into our wallets if we were ever to start it, let alone complete it. We bought about €350 of flue. ... And then two weeks  later were given some free second hand stainless steel parts. But not everything we needed though.

10 Since the Ianto book was first written, new ideas have been tried and tested and are worth incorporating: lose the feed box ash pit (it burns out) and lose the small barrel (it can fill with smoke) Erica recommends leaving them both out. Also take a look at the additions Peter de berg has made (at www.rocketstoves.com) We added his steel plate to the feed tube. It allows for ventilation and protects your first fire brick from damage when loading wood. we found it works. We also made the transition bigger by cutting a rectangle out of the oildrum. (Search for transition(?) plenum(.) a great thread has been recently started on that. I found that part of the build the most challenging, but not impossible.

11 Before you build, find out exactly what the adjacent walls are made of. If they are of  combustible material, it is good sense to move the rocket to a safe distance, and/or make the wall safe by adding appropriate cladding. Same for the floor.

12 Check the building codes for your area, working to them may help you to make your installation safer.

13 It has been suggested more than once on this forum, that if you have a fire in your house, (even if the rocket didn't cause it) your insurance company may not honour a claim if they see you have a non-standard, non-code compliant rocket installed. If this is likely to cause you problems, perhaps you should find out ahead of time or build to code compliance? We made the decision that if it came to it, we needed a RMH more than insurance. Our barn is an old milking parlour, with 18" thick granite walls so no fire hazard there. We showed our finished Rocket to our insurance man, showed him build pictures and explained fully how it works. He said he was satisfied, thought it a great idea and classifiable as a woodburner, which reminds me, I should get that in writing!! The local firefighters were impressed too - I hasten to add that they were on a fundraising visit not here to put out a fire.

14 I didn't build a mock-up and fire outside, but in 2007 we'd started one inside and got as far as fitting the oil drum, so I did understand what I was doing and we built to Iannto's exact dimension. Even so, be prepared to rip your build apart before it's even complete, you may make mistakes. With that in mind,  I'd recommend using materials that will come apart easily. I thought I was doing the right thing in using refractory mortar for my burn chamber. Until I had to take it apart because we weren't happy with the placement. Chipping off the mortar damaged the (expensive) firebricks. I used clay mortar after that. The second strip down was a cinch.

15 I recommend you get an understanding of how materials expand and contract when they are heated, Build expansion joints into your burn area. I couldn't,t find definite answers to where, how and what. So I ended up using more firebricks ( I reduced the number of different materials, as they each expand at different rates) I added thin cardboard to the vertical and horizontal mortar. No idea if it worked/was even needed! The one house brick I used in the feedbox (ran short of firebricks) cracked and had to be replaced.

16 Do not underestimate how much digging and mixing of cob you'll be doing. I humbly disagree with a previous posting that it doesn't take much! 'How much' is subjective, the fact I'm nearly sixty and the old man hurtling toward seventy, may have coloured my perspective. (Even with the help of a cement mixer.) Halfway through I  began to think I'd bitten off more than we could chew. I couldn't tell him though and we just kept makin' that cob. LOL  the amount you need will depend on your bench size and how many rocks you can build in.

17. It's definitely more fun if you do this with a crowd - I posted on a local forum before our first build in 2007 and 14 people turned up none of whom had ever seen a RMH let alone built one. Me included. IMHO You'd need to be very organised and have a well conceived plan of action. I spent the weekend moving from group to group facilitating, and didn't get to play much! Feedback from everyone was that they'd had a great time, but I was a teacher in a previous life which helped. When it came to the 2015 build, we decided to go it alone so we could work at our own pace. It was hard work but we had a real sense of achievement when we fired her up.

This is just my four pennies worth. I'm not an expert. I have started and ripped apart 3 and completed the fourth. Love it! No regrets, life in winter in Europe is more than bearable now. Would I do it again, Absolutely, no question: we use less wood; have downsized the ash bucket; we can now use our tree prunings; no more tarred woodburner door; no more cold mornings; we have 24hr warmth on two 2 hour firings each day; always starts easily; easy to repair/make cosmetic changes... we raise seedlings on it ... I tuck my clothes under the cushion so they're warm in the mornings, and, as a result of digging up the clay, we have the foundations for a traditional Normandie Wood-fired bread oven.

My advice is just go for it, I reckon anyone who can read and is fairly able-bodied can do this, don't try to reinvent the wheel, stick to what works. (Says she who added an oven on the front!)

Bon courage
Lesley
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pollinator
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Location: Wisconsin, zone 4
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Lesley, that is just beautiful.  Great write-up also.
 
C Jones
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In 17 easy steps
 
lesley verbrugge
Posts: 47
Location: 48°N in Normandie, France. USDA 8-9 Koppen Cfb
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Mmm was a bit of a marathon post LOL and I forgot to add something I found really useful:  I'm not a bricklayer but something that helped me keep the firebox, burn chamber and chimney to the right dimensions was a 7”x7" piece of ply nailed to a piece of 2x2.

Best of luck with your build C and many thanks for your kind comments Todd

Lesley
 
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wife and i are 70s.  we built one in month in our living room in jan  midwest.  hard work and we bought our clay.  it works perfectly with ericas plans followed to the tee.  we love it.  heats our old farmhouse much better than large new englander.  if you are considering doing it i would say do it.  our pics are somewhere on this site
 
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