A fuel source you might not have considered

First off, apologies if this has been discussed here. If it has, I guess I missed it. If not, I hope my experience is helpful.

I don't have a RMH. I wish I did, but I don't. My house just isn't set up for one. Maybe someday, in another building. Meanwhile, I heat with wood in a wood stove, and have been doing it for many years, the past few years exclusively. No electricity, except for an electric blanket on my bed. There's no gas line on my road, and I won't use oil. No tank anyway.

My stove is a Tempwood, from the late 1970s. They don't make them anymore, and if they did, they'd be illegal, because they have no catalytic converter. It is a welded steel box, with a double steel bottom, lined with firebrick. It is a pure downdraft, with a round cast iron lid in the center, and two downdraft ports, one on either side of the lid. Those are the only openings. Each of the ports has a draft regulator. This stove is as airtight as airtight gets, and because of the downdraft, there's a lot of secondary combustion, and far fewer emissions than you might think, sometimes none visible at all.

When the downdraft ports are opened all the way, it allows the stove to get very hot, and radiate a lot of heat. This makes the stove more efficient the less fuel is in it. That might sound counterintuitive, but that is my experience, based on more than 30 years with this one stove (except for the leaky, expensive yuppie foo-foo stove my ex insisted on for a while -- but I digress).

This isn't so much about the stove as it is about the fuel. And I'm not here to claim that this stove is better than a RMH. I get a lot of stored heat from the brick hearth I put in when I ripped out the fireplace some 35 years ago, but clearly my setup hasn't the design or the mass for heat storage that a RMH provides, and I'm just plain jealous of those who do have it.

When I started burning biochar outdoors in 55-gallon drums, part of the hassle was starting the fire easily, till I remembered that the fire starter in the hardware stores is mostly just sawdust and paraffin. It occurred to me that the waxed cardboard cartons that vegetables are shipped in might do the job. The supermarket where I get cull produce for my cattle and hogs has unlimited quantities of this stuff, and the recyclers won't take it; only the landfill will. Well hell, we can't have that. That's a resource. They love that I haul it away for them.

So first I started using it to start off each biochar burn. It worked like a charm. One match did it. Then I started the BBQ with it. Perfect. I use only lump charcoal and fruitwood from my trees -- no briquets allowed on this child's place -- and the charcoal burned readily with the waxed cardboard.

Then I used it in the wood stove, and found that with it, I could do away with kindling altogether. And I have.

So next I thought: What if I did away with using cordwood at all, and just used the cardboard? Well, I can't do that 100 percent. I'd like to get some sleep and not be feeding the fire all night. If I had a RMH, yeah. But I don't.

But I did find that I could cut my use of cordwood -- or any wood -- WAY down just by feeding the waxed cardboard, rolled up loosely, into the stove to bring the house up to ambient heat. My house is very well insulated, and I found that with the outside temp in the 20s, and the inside temp at about 50, that I could get the inside temp up to 65-68 in just an hour or so feeding waxed cardboard -- a little at a time -- into the stove. With THIS stove, the experiment has been a success. Most other stoves are leakier than mine.

But now think of what this fuel might do in a Rocket. I'm guessing that it might be better than wood even. Has anyone here tried it? It's free and abundant for the taking, and we don't have to cut down trees to get it -- they're already cut down.

I have no idea, none whatever, what the wax might do to my stovepipe or the chimney. I am a fanatic about having my chimney swept and my pipes cleaned every spring, so I guess we'll find out then. I apologize in advance if some might find this offensive, but I don't worry overmuch about emissions. If I did, I wouldn't be heating with wood in the first place. I am retired on a fixed income, and wood it is, wood it has been, and wood it will be. I try to be as clean as I can. Whatever we do there are tradeoffs.

I would love to hear if people have any experience with waxed cardboard as heating fuel. I have no personal experience whatever with RMHs, just what I read here and listen to on the podcasts, and what's in Ianto's book. But I am guessing that waxed cardboard could be better than wood for RMHs. Maybe I'm full of (gas). If so, I hope someone will set me straight. I'm a big boy and I can take it. If you have read this far, thanks. I hope it is helpful. Cheers.

I have burned a shitton of cardboard in my RMH, it burns clean and hot, I was doing it mostly to get rid of it. The downside is that one day of burning cardboard produced as much ash as a week of burning hardwood. Glad my RMH dumps its ashes into a can in my basement!

Daniel Truax wrote:I have burned a shitton of cardboard in my RMH, it burns clean and hot, I was doing it mostly to get rid of it. The downside is that one day of burning cardboard produced as much ash as a week of burning hardwood. Glad my RMH dumps its ashes into a can in my basement!

How do your ashes get dumped into a can in the Basement? How does that work?

Daniel Truax wrote:The downside is that one day of burning cardboard produced as much ash as a week of burning hardwood.

Two things about my particular setup. (1) The downdraft nature of my stove leaves me with very little ash. (2) There is cardboard and then there is cardboard. The waxed stuff burns so hot that just about all of it is consumed, and it leaves a lot less ash than straight corrugated would.

I clean out my stove about once a week and get about a bucket of ash each time. I scatter it in the hog pasture and the hogs eat the tiny amounts of unburned charcoal, and work the rest into the soil for spring reseeding.

Ivan Weiss wrote:First off, apologies if this has been discussed here. If it has, I guess I missed it. If not, I hope my experience is helpful.

I don't have a RMH. I wish I did, but I don't. My house just isn't set up for one. Maybe someday, in another building. Meanwhile, I heat with wood in a wood stove, and have been doing it for many years, the past few years exclusively. No electricity, except for an electric blanket on my bed. There's no gas line on my road, and I won't use oil. No tank anyway.

Hey Ivan. We use a very....very old wood stove that was made in the 1950's and is quasi-refubished. It's an upright. Sealed the best we can seal it. We've burned wax cardboard before...but it's not an effective heat source in ours - plus it makes a weird smell. We were using cardboard thrown away from our village's (population 300 "three hundred") bee keepers. Our village's main source of money is honey.

I wanted to suggest sawdust to you - but you'd have to find a way to build a very slow motor (very slow) that just trickles the sawdust down into the firebox. It's extremely efficient - burns very clean - and hot.The sawdust goes into a hopper, and then via the motor - gets trickled down into a slow-spinning plate with holes on it, and as it moves...little bits of sawdust is felled into the firebox.

You've probably heard of this before - but I can attest to it's efficiency and effectiveness. Burns all night long - so when you wake up in the morning - it's nice and toasty, the same as when you went to bed (providing you don't run out of sawdust by morning!)

Jamie Corne wrote:I wanted to suggest sawdust to you - but you'd have to find a way to build a very slow motor (very slow) that just trickles the sawdust down into the firebox. It's extremely efficient - burns very clean - and hot.The sawdust goes into a hopper, and then via the motor - gets trickled down into a slow-spinning plate with holes on it, and as it moves...little bits of sawdust is felled into the firebox.

You've probably heard of this before - but I can attest to it's efficiency and effectiveness. Burns all night long - so when you wake up in the morning - it's nice and toasty, the same as when you went to bed (providing you don't run out of sawdust by morning!)

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Thanks Jamie. I had heard of this. Problem for me is that we have periodic power outages in my rural community, which seem to coincide with the worst and coldest weather. The plate would stop spinning, and there I'd be.

Ivan Weiss wrote:

Jamie Corne wrote:I wanted to suggest sawdust to you - but you'd have to find a way to build a very slow motor (very slow) that just trickles the sawdust down into the firebox. It's extremely efficient - burns very clean - and hot.The sawdust goes into a hopper, and then via the motor - gets trickled down into a slow-spinning plate with holes on it, and as it moves...little bits of sawdust is felled into the firebox.

You've probably heard of this before - but I can attest to it's efficiency and effectiveness. Burns all night long - so when you wake up in the morning - it's nice and toasty, the same as when you went to bed (providing you don't run out of sawdust by morning!)

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Thanks Jamie. I had heard of this. Problem for me is that we have periodic power outages in my rural community, which seem to coincide with the worst and coldest weather. The plate would stop spinning, and there I'd be.

Hey Ivan,

Actually - you can power the disc using this method:



I mean - there's a bit of work to build it...but in the long run, it could save your life. It's something new to Dave and I - but we're really working on getting ourselves prepared for living without electricity (due to the amount of turbulence we're going to probably see if the political arena doesn't get it's stuff together).

In that video - they got up to 12 volts, and someone could probably get more if they toyed around with it enough.

I do like your thread here though and would be highly interested in reading any other suggestions. I think we're all on the same path here - and it's great...that this forum even exists. I very much appreciate all the input and knowledge here. It's become my favorite site to read - and occasionally post to.

Has anyone tried those Briquettes? I see a lot of videos of people who use old newspaper and sawdust that is wet and then pressed into a little brick. They act as though it is the best thing since sliced bread. It does not seem like much work to get rid of paper and other junk.
Does it last long? It looks like if you compress it with a jack it would be pretty solid.
Any Comments?

The problem with the wet mache bricks is the space (and weather) you need to dry them. It takes a lot of shelf space in a dry climate to get them into a non-moldy brick. I don't know how you would keep them dry and mold-free in a wet climate.

And they do take a lot of time. Not worth it for me because we have an over-abundance of real wood to be scavenged (blowdown, dead-standing, power-line trimmings, and tops from timber harvesting). Way better ROI on the real wood. But if you were somewhere that didn't have a lot of free wood but you did have free paper and/or sawdust--it could make sense.

One reason I wanted to burn that stuff also in a Brick is because it is junk that is still around the property. My Only other choice is to use a chipper and mix it in with the soil, Compost it in. like you there is a lot of wood around. But also paper and cardboard. I hate to send it to a landfill.

Pellets --- Wood Chips

Thinking again last night. I see one source that people use are these pellets. You fill a tube and it works down to the Fire Pot. I was thinking about wood chips instead of pellets. Real wood that goes into a chipper comes out as small pieces of wood. One problem I thought of was their shape may be a problem flowing down into the Fire Pot. Has anyone used them instead of spreading them out as compost?

My understanding is that ash is a property of the fuel, not the stove.

I always caution people against burning paper and cardboard because most of it is coated or altered in some way so that it's not just wood. The worst case is plastic-coated cardboard that's shiny, but coated paper (all of it is coated with something) isn't good, either. Burning plastic and other petrochemical products in a residential setting is a bad idea. The chemistry of these reactions is complex both in the burning and cooling of exhaust gases. Just to give you an idea, there are sometimes provisions for cooling incinerator exhaust gases so avoid a certain temperature window in which dioxins can form. And all sorts of chemical scrubbers are also in common use. If you don't have that kind of infrastructure, I'd encourage you to forget the petrochemicals and just burn a proper fuel.

those pressed briquettes work fine and will dry in most weather its just a matter of time. best solution is to make a heated space to dry them........ hmm maybe a cavity in the RMH?
I encourage folks to make those briquettes in summer out of dung and sawdust with a bit of paper as a binder (i dont like using food for a stove but flour paste works well as a binder also). you can use rather large wood chips as well if you use dung and paper pulp (you must add enough dung and pulp to make the briquette in the press). I liked the result of our experiments with them and think its a dandy idea that could be made into a business for someone.

Wood, saw dust, sticks.. all make such good amendments for the soil, I would love to see the rocket mass heater used to burn the stuff that doesn't compost as well. Like paper and cardboard. If we could run it on just paper or card board that would be wonderful. As for that machine that slowly feeds pellets or saw dust into the burner.. could we figure out a way to run it off the heat produced by the stove? I wouldn't want to use electricity or gas to run the stove if I didn't have too. I don't have a rocket mass heater yet.. but its a huge goal of ours. If we could build IT, and make pellets outta junk paper,(or better yet.. make the pellet making machine), make a pellet feeder for the stove... I think they would sell like hotcakes. Like the whole system together.
Advertise "Turn your junk mail into heat for your whole home!"
I love that Paul is contiguously improving the rocket.

Does the burning of the wax pose any potential issues in terms of gumming up your chimney or parts north of the combustion chamber?

I run a newer efficient woodstove sometimes and the instructions very clearly warn strongly not to burn anything other than wood in there.

Bio-briquettes should be doable. Shred the cardboard and/or paper and soak it in water. Put it in a mold, then press it so the water drains.

Making a donut-shaped briquette (round with a hole in the center) would work great in a RMH's round feed tube. If the briquette is a foot or two long, and you feet tube is long enough to hold several of them, you may be able to go a good while between refueling. The hole in the center brings air to the fire at the end of the briquette and the fire works it's way back. To reload, just insert more briquettes, pushing the last briquette on fire toward the stove, with the new briquettes now behind it. Fire works it's way back again, where the process repeats.

Also, has anyone thought to heat mineral oil with the RMH, then circulate that hot oil to radiators or an underfloor heating setup, throughout the house, then back into the stove for reheating? Seems like that might work better than heating water, which boils at 212 F. The oil can be heated much hotter without increasing pressure, so it seems like a better heat carrier to distribute heat from a fire or solar batch heater throughout a home. Just a tought.

Nice to be BTW. Looking through all the posts now. Lots to learn.

Oh, forgot to mention that you can use a solar dehydrator or heat from your stove to dry the briquettes much quicker. There is lots of free paper and cardboard out there, so briquettes might make sense for a lot of people. Also, the briquettes can be pressed into whatever shape works best for an automatic feed system. That alone might make them worth trying.

Hello Ivan, Reading about your Tempwood stove led me to google it. Yep, that was the same hotbox I had for years in the 1990's. It didn't have any labels on it.
I did find a current website at www.tempwoodstoves.com It looks like they still make them in Adams, Mass.

Now I'm using a small Century s244 secondary reburner. For thermal mass I came up with the Idea of 6 SSteal pots on top (18 gal) and 2 x 8 gallon "tamale pots" stacked on each side. (32 gal) for a total of 50 gal of mass. I also have 2 cast iron fire backs in intimate contact with the stoves sidewall (18" x 20" x1"). The tamale pots hold them up.

I have access to a large supply of plain cardboard boxes. I'm thinking of cutting it to the firebox size and putting a cast iron grate on top to weight it down and slow the burn a bit. Wood on top. I'll be trying this as the shoulder season gets here in Connecticut (I hope)

Thanks for the Tempwood memories. I spent those winters in boxers during the burn.