From the burn tunnel to the exhaust yes. But no, the feed tube is not proven design, its not even a feed tube but a feed box.
I know the risks of disappointment if the feed box doesn't work, but I can always back out and fill in the feed box and quickly turn it into a traditional feed tunnel in the case of failure.
posted 8 years ago
Erica to be more correct the proportions are from proven plans (mostly proportions from the RHM book), set up in the yard as a test bed. This design is more robust on the outside to support the weight of the barrel.
PS in a former life I was a full time professional tattoo artist: proof Daniel Truax Tattoos. I am going to put those old creative skills to work with a great barrel decoration.
My idea is simple, cheap, easy to make and install. I can't wait to get to it but alas I have to have a working stove first.
Tidy project - yeah, firebrick cuts pretty slick on a masonry saw, and a grinder will do it in a pinch.
I can see where you're going with the bigger fuel box idea.
I am patiently sawing 16-18" logs down to 9-12" for our little fuel feed, one by one as we bring in another load for the day. Ernie has assured me that if we ever buy another cord of firewood, and they ask if he really wants 12" even though it will take them longer, he will say Yes. Perhaps I will get ambitious and cut down the face cord with the chainsaw. So yes, "Can I make one of your efficient mass-heaters but have a big firebox like I'm used to" is a very popular idea.
The main problem with any larger box is
- getting the fire to burn clean enough to NEVER put creosote in the cold exchanger piping or downstream chimney,
- to make it so you can add wood without spilling smoke into the room.
To do a true 'batch burn' where you close the door once the fire is going and don't open it again, you have to calibrate the system for your BTU needs pretty closely. These change with the seasons and weather, so you compensate for the weather by doing every day / alternate day firings. These are best done in advance of a major weather change. Even if you are a little off, the heat is still very even, compared to woodstoves or forced-air furnaces - it might be the difference of a T-shirt day or a sweater day, and you can double up and burn two fires the next day if you think it will help. Problem is, 2 fires means 2 start-ups, the smokiest part of the burn. And smoky means creosote, in a low-temperature heat-exchanger.
To have the pleasure of using the same small heater spring, winter, and fall, and burning the amount that makes you feel cosy, without re-starting a new fire, you need to be able to feed wood while the original fire's still going. Also, sometimes you want to adjust the fire. Adjusting can be done through a relatively small hole, but adding a piece of wood needs a big-ish opening. I have never yet seen a RMH system with a separate air feed, where you could close off the secondary air, open the fuel/air main feed, and drop in a piece of wood, without releasing some smoke. I believe this is a limitation of the human biology only having two hands, not of the stoves themselves, but we works with what we's got.
If you get it to work so you can do all these things, and it's putting out clear/white steam/fog and not a hint of blue or brown in the smoke, it will be a truly unique innovation.
Otherwise, you will just have the fanciest firebrick hearth yet seen on a rocket mass heater.
Another place to look if you want some options is 'bell stoves', that's the term for a masonry heater with a mushroom-like downdraft over the initial up-riser like our RMH's have. I don't know how much heat-exchanger they put on the bell stoves, or what kinds of feeds they use. I think they're simpler, though.
The rest of it looks good, and I do think you've innovated in a way that you can fix with minimal hassle if it doesn't work out.
I cut a hole knee height in my wall for the exhaust. As soon as I did the negative draw of the house let cold air in.
So I was pretty sure an exhaust pipe test there would fail. And it did. Couldn't keep the stove firing consistently out the house and it kept from smoking back.
Funny thing in the hole for my steel wood stove at head height has a good positive draw and there is only a 4 foot difference. And that is before the 20 feet of chimney is attached.
So I am going to try a second fire today with the exhausted headed up the steel stove's chimney. As soon as I get the house warm and the steel stove out that is.
posted 8 years ago
looking good, keep us posted on your progress
posted 8 years ago
So my second test fire went well.
I hooked up the 8" pipe to my exterior 6" to get past the negative pressure at the level of my rocket stove.
It fired right up, it even had a good draft without any fire as you can see by the incense.
So I heated my house all day with it, this morning it was 20F and by 2pm it got up to 40F which is very warm for this area this time of year. Right now (8pm) its back down to 32F.
I fired it twice and it got the ceiling of the room it was in to 90F in about 2 hours, the floor was low 70Fs. It took my old wood stove about an hour to do that but it would use a lot more wood faster.
The heat in the house seems more even from floor to ceiling. And there isn't that intense heat in the corner of the living room that we needed to throw the heat to the farthest rooms. My house has serious insulation problems, some rooms that I have finished have R60 ceilings and R40 floors and walls, and other walls were ruined by a family of squirrels when the house was abandoned. So they have little insulation at all. It was a great thing to cook some bacon and eggs on top (it is too high for comfortable cooking since its being built on a wood floor) and to know all this time, work and capital that went into this project so far, wasn't a complete failure.
There is no mass laid in yet, I have to go into the basement and put at least one more post under where the heat couch will be. I will heat with it tomorrow as I dig that and lay the footers. But even without the mass it seems to "hold" the heat it makes much better than the old stove.
Its a shame that went I finally bite the bullet to make this stove we get the mildest winter ever!
Other notes, the top of the stainless steel barrel was around 500F, the exit temp was 150F with 30" of unmassed pipe. The exit temp from the barrel was 250F.
Oh yeah the picture of the exterior exhaust was with the stove running.
And the hole in the siding in the outside shot is where the exit of the first failed attempt was.
Yes, I was happy when I test fired it for the second time and it worked.
I'll be satisfied when its done enough to sit on.
Its currently 25F outside but it is supposed to get up to 60F and sunny so... today I am going to pull the trigger and move my stainless steel triple wall chimney to permanently hook it up to the rocket stove.
Hi Daniel, photos of your build continue to amaze me, nice work! What are the mid run tee (cleanouts?) about? If they are in fact just for cleanouts, it looks like you have it all covered with the cleanouts at the ends and more is not necessarily better as it offers more places to leak and a surface break in your bench right in the middle where you want to be laying down. Just thought I better ask and see what that is about? Canyon
posted 8 years ago
Yeah I was torn on the middle ones. My thoughts are that this stove is going to be around in this house for my family and yet to be born grandchildren long after I am gone. I like to think of it being used 200 years down the road. Trying to clean out a horizontal pipe and reach 4 feet without the use of a vacuum would be a pain in the ass.
As for the leaky cleanouts. the whole thing leaks at every joint right now when fired first cold since the stove is trying to push that slug of cold air on the outside chimney. We can remedy that with a little lit paper in the last clean out. After she is warmed up it actually pulls a little air from the room into each joint as can be seen with incense smoke.
So I am not worried about leaks into the house, I am worried about the break in the middle of the bench. I plan to tile the bench completely when done so I hope I can make some fancy recessed handles for the middle cleanouts with the plugs flush.
Or I might just get pissed off with them if I can't make it work and plug them permanently. But I'd rather have them there and not use them than want them later.
Its been quite warm here during the day but we have been lighting one fire at night and the stove is still putting off heat in the morning even without the mass.
Can't wait to start working on it again tomorrow, (rotating shift worker).
posted 8 years ago
Since the weather outside is suitable for work, this project is on pause until Fall. Unfinished or not it is heating the house very well.
When I get back into I'll brick the outside of the fire chamber, try making it into a side loader with a masonry door, add a secondary air intake, decorate the barrel, add mass to the bench and make it more organically shaped and finally I'll tile the bench in blue penny round tile.