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happy past turkey-coma day! RMH question

 
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I'm glad to be here!  Call me Lee, much easier than the official Elizabeth Mae you are probably seeing...?  I'm not exactly a typical permie- I lived off grid for 6 years on solar, huge garden, chickens, composting toilet etc, but now I live in a little town on a big lot in what I call the southern Canadian annex of NY.  (30 miles south of the border in upstate NY)
I can meat and veg and bake bread and mess around with ferments and someday will get enough renovations done to plant a garden, but currently I'm plotting a rocket mass heater for my basement.  It may end up being a surreptitious heater, have to investigate that LOL. 2600SF 1870s Victorian, will be a duplex someday when I get it presentable- probably 5-10 years since I'm doing most of it myself.  I'm not planning on moving, but I am a sustainable minded person by temperament and between snowmageddons and economic stupidity and political hysteria.... I'm just a practical kind of lady.

I've lurked for years, but I need to ask a question now so I went official-
I have many chimney blocks from 2 exterior cement chimneys that came with the house. Neither are used now. Both are 16x16 concrete block with a liner that had been poured in around a 6" form of some sort that was removed after the liner had set up.  I've been told this was a thing back in the late 70s, maybe early 80s.  Both chimneys were venting natural gas boilers, not oil or wood.  So not sure what the liner is, but probably wasn't designed for super high temps, as I believe NG exhaust is on the low end of the temp. range.
My question is this- if I used them with the 6" dia hole in the horizontal orientation as part of a bench, would the cement portion be a decent material for storing thermal mass from a rocket heater?

If not I will dispose of them before they get hit by the plow this winter as they are next to the garage....

Thanks for all-y'all being here and a great resource for info we don't see many other places....

_/\_  Lee
 
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Welcome to the forums Lee! Its great to see another Upstate New Yorker here even if you are essentially a Canadian

I'm sure one of our many RMH enthusiasts might have an answer for you but if you don't see much traction here in your introduction please feel free to post in the rocket based forums to try and find an answer!

I'll see you in the threads!
 
rocket scientist
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Hi Lee;
Welcome to Permies and Welcome to the wonderful world of Rocket Science!
So you want to build an RMH in your basement.
Is this a basement that will be occupied? Or will you need to go down to feed your stove?

It sounds to me that you are thinking of a J-Tube rocket with a piped bench and a solid mass.
I suggest building a 6" batch box with a brick bell instead.
An 8" J-Tube needs wood every 45 minutes, and a 6" J-Tube needs wood every 20-30 minutes.
A 6" Batchbox needs wood every 2 -3 hours or so.

So, about the used concrete blocks.
Concrete does work as a mass but only away from the high-heat.
They could be utilized at the bottom of a bell but not near the core or riser.
Using the 6" hole as piping is just not a good idea in your case.
You could only build a 6" J-Tube with them and that's not nearly enough for an old Victorian home.

I would save those blocks for a different project.

 
elizabeth mae brown
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thomas rubino wrote:Hi Lee;
Welcome to Permies and Welcome to the wonderful world of Rocket Science!
So you want to build an RMH in your basement.
Is this a basement that will be occupied? Or will you need to go down to feed your stove?

So, about the used concrete blocks.
....
You could only build a 6" J-Tube with them and that's not nearly enough for an old Victorian home.



well thank you!! actually there are currently 2 boilers and 10 cast iron radiators and that's not really enough to heat this old beast LOL.  no the basement rocket stove was mostly a tinker-project that would use up the scraps from wood projects, and all the lathe strip I'm demo-ing.  I'd be feeding it when I was in the basement, which is my happy place.  It would save me the effort of carrying the wood scraps upstairs out to the fire pit.  being in a small town I'm cautious of fire when it's at all windy and I first thought I'd put something like a crappy sheet metal stove out there to use up the wood when it's windy but I think this would be better use of my time.  If I figured it out at all I'm also thinking it would be awesome to run some ducting thru the sunny side of the eventual semi-inground greenhouse thing I'm planning.  Not for winter heating- that's silly in Watertown NY- we're one of the snowiest places in the US.  But come spring the earlier I have warm soil the more I can maximize a somewhat short growing season.  
So- partly learning, a tiny bit practical, a whole bunch of cool ;-)
Lee
 
elizabeth mae brown
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I said out there about the wood-stove- I meant in a detached garage. That was the other place I'd considered building my experiment.  Just kinda running out of space out there- it's currently being partitioned to contain my 2 elkhounds.  plus a snowblower.  and a car.  so garage isn't quite viable this season.
 
pollinator
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Welcome Lee! Our household is also pondering options and specifically pros/cons of rmh vs batch box vs masonry heater. Right now we’re leaning heavily toward masonry heater because it’s more practical from the standpoint of not needing so much babysitting (as Thomas mentioned) regarding how frequently one needs to add wood to an rmh. It’s also not going to void the homeowners insurance requirements for wood fired heat.
My first thought about your idea was the labor involved bringing those blocks into a cellar from outside! I’m very familiar with what they are, and they are heavy!! But, you probably have a plan for that, so I’ll progress to my actual point (finally!)- you mentioned a greenhouse and heating the soil earlier. Since the blocks are already outside, what if that tunnel was under the soil in the greenhouse? Easier to bring wood scraps out of the basement than concrete blocks in, and you could start firing that rmh up in late February/ early March when the daylight is gaining, to pick up an extra month of growing. OR- Depending on how your buildings are configured, if the greenhouse was attached to the house or garage you might be able to have the rocket inside, and then run the mass tunnel through the wall below grade and into the greenhouse.
There’s definitely tons of information in the forums here, as well as many knowledgeable people discussing rmh ideas, so it’s certainly a good place for you to join in as the tryptophan wears off.
 
elizabeth mae brown
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oh thank you Julie!!  actually the future greenhouse is going to be about 60ft away lol. other side of the asphalt area between the house and the garage.  and yes- those blocks might just stay out there under the snow until whenever.  there are new stairs going in the back half of the house from basement to attic, to replace the horrible Victorian 'death stairs' that currently serve to get upstairs.  so plenty of opportunity to drop things down or hoist things up when there is a stairs-sized hole in the floor!!
yeah I might look into a masonry stove.  the hole in the very thick stone foundation that went to the old chimney is still there if need be- that would have been my exit for the rocket.it'll be a year or 2 of thinking/designing before anything begins- I have plenty of other construction tasks to do with higher priority.

thanks for the idea!!
Lee
 
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A rocket mass heater is actually a subset of masonry heaters, with a particular high-efficiency firebox. Either a J-tube or batch box can be used for combustion, while the mass can be either a piped bench or a bell cavity in any shape including bench. A batch box can be made to fit the letter of International Building Code for masonry heaters, so simpler to get permission for if needed. Code requires construction or supervision by an accredited professional. A batch box with bell can reliably be built by a good craftsman who can follow instructions, while a traditional masonry heater generally has a lot more complications and probably needs a pro to build reliably.
 
Julie Reed
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Glenn Herbert wrote:   A batch box can be made to fit the letter of International Building Code for masonry heaters, so simpler to get permission for if needed. Code requires construction or supervision by an accredited professional. A batch box with bell can reliably be built by a good craftsman who can follow instructions, while a traditional masonry heater generally has a lot more complications and probably needs a pro to build reliably.




Our issue is not code, as there is none here, being very rural, but insurance is a different thing. So far they consider the batch box design (as well as rmh) to be experimental, vs the centuries of consistency of masonry heaters. I’m curious what the complications of a masonry heater are, in your opinion, as we haven’t found them to be all that complex from what we have seen and learned thus far. They are definitely more material, weight and time depending on size, but aside from needing reasonable masonry skills I’m not seeing any particular complexity.
Here’s an interesting older thread along those lines, specifically the discussion between Mike and Al- https://permies.com/t/43809/Masonry-stove-diy-build-feasible

elizabeth mae brown wrote:    …the horrible Victorian ‘death stairs’…



That is such a great description of those old narrow steep staircases! My grandfather’s house had them, and as a kid I loved them, but not anymore!
 
Rocket Scientist
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I dont know if I have ever seen a full masonry stove build featured in detail on this forum?

From my very limited knowledge, a masonry stove is a large, stand up, mass of fire bricks laid to form a series of channels within the mass?
Whereas a bell, uses a similar quantity of brick (often laid as a double thickness wall) but is hollow.

I am an experienced brick and block layer and would be very sure that a hollow bell would be a lot easier and faster to build than a matrix of channels and chimneys,  but not really a problem for an experienced person to build either.

My main concern would be obtaining precise, accurate and tested  plans to build a masonry heater?
Once the masonry heater is built, it would be very difficult to adjust any of the interior without a tear down!

From my own experience and from reading many thousands of word on this forum, it seems very unlikely anyone could guess the correct measurements and even small tolerance mistakes or compromises can simply stop a stove from working!

Just my personal thoughts but a batchbox and bell seems to be a far easier and more importantly ….a more reliable option.

Where I live, there are no house insurers who would consider any form of wood burner without a building code pass.
 
Glenn Herbert
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With brick-by-brick construction plans, a good craftsman could build a traditional masonry heater, though a number I have seen (pictures/descriptions of) have extremely complex fireboxes in search of greater efficiency. I believe a batch box would be at least as efficient and considerably easier to build. The fun part is teaching insurance reps this. (And code inspectors...)
 
Julie Reed
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From what I’ve researched there are a lot of variations, from simple to intricate, but so far I haven’t encountered anything suggesting exacting tolerances. Friends in Europe report that many people build them successfully without any journeyman level skills. Firebrick would only be needed in the firebox and immediate flue area. Here’s two common examples- one from the Living Homes book by Thomas Elpel and one from the Masonry Heaters Association website.
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[Thumbnail for AB35A9CE-61B0-4012-AF5A-8D3348AD64DC.png]
607E2F35-B26C-4E45-8287-F49208BBDDD1.png
[Thumbnail for 607E2F35-B26C-4E45-8287-F49208BBDDD1.png]
 
Of course, I found a very beautiful couch. Definitely. And this tiny ad:
rocket mass heater risers: materials and design eBook
https://permies.com/w/risers-ebook
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