Stephenson would be proud.. Well not quite. but the Mk 2 is the biz.

Remember this " https://permies.com/t/40044/rocket-stoves/Stephenson-proud " well no matter what the criticism or lack of,,, It worked " WORKS" but, as wives go, they are petulant creatures when they want to be. Oh yes. When I made the stove she moaned like hell. " the dust, the mud, the barrel the etc.. One year in and I wanted to improve the system. " the dust, the mud, the barrel the etc.. Well now I have cut the mooring lines and decided to go for a divorce or a happy wife,,, maybe,, without the " the dust, the mud, the barrel the etc.. I've kept the barrel because that is the essential of the rocket but my biggest complaint about the systen was,,, " It's not very homely" and to be honest. A standard rocket mass heater is not very homely no matter what you use to try an cover it up unless you happen to be a burned out hippy with no means of support apart from selling organic twisted carrots and wilted lettuces and don't actually give a shit what it looks like as long as it's cheap. or even better,,, "FREE".. So. I did this. AND, IT WORKS. with waste wood at the back, with logs at the front, And with a basket of pellets in the waste wood box with the flaps closed down I have also put a flap valve between the exhaust tube and the mass block to be able to just heat the room without heating up the mass block, ( for chilly autumn evenings Yet warm days) so I can choose between warm room or hot house.The new open front of the stove means that I can choose my fuel and also how I use it. My wife likes an open fire so she can chuck a log or two on the hearth and enjoy them yet they will still be running the rocket and the mass heater. If we decide to go out for the day,, we can load the basket with pellets and leave it burning with the flaps closed and the air inlet on the door open. Nice and cosy when we return. I'll post more details and measurments when I have time. Cheers. PS. Sorry hippys. I was one myself but sitting on a stone bench never got me going then and even less now. no matter what temperature it's at. Forget the organic shapes and cater to the organic people who would like something like this without the "Cool Man" element. I have integrated the system into my house and it works without curvy rock hard window seats. Try it. You'll be surprised.

Photos

Gusmus, what does this have in common with a rocket?

Well you see "Satamax", I always find it helps to read all of the post before commenting. That way you don't miss out on the important bits like the instructions.
If you click the link to the original post " https://permies.com/t/40044/rocket-stoves/Stephenson-proud " you will see that it is a rocket. This is simply a new front end which allows a bit more variety of usage and also lets you see the fire which although doesn't really matter in terms of performance, you must admit an open fire gives a little more homely feel. I've run this up twice now and it seems to work fine with both pellets and waste wood. I've yet to try the open hearth at the front but I dragged some pellets forward during the last test and it seemed to work fine with the door both open and closed which surprised me as I was expecting to see some smoke out of the top feed tube with the door open. Here's hoping.

Well I don't like to say "I told you so" ,,,,but "I told you so", It does damned well work and IT IS A ROCKET MASS HEATER.

It's not quite cold enough to run it yet but I wanted to try it out before I put a new porch roof on and had to change the chimney run. It works great. no smoke, no blow back, and it rockets like a rocket. It also rockets with wood, pellets, and compressed logs in both front and back combustion chambers. My missus loves it because she can see the fire and burny bits. More homely I think.

<Cross posted with the photos above, which clarify my questions>

So Gusmus, , you seemed to get cranky with me. No need to be.

I have questions tho.

Are the feed tube, burn tunnel and heat riser insulated?

How long have you been running it?

Do you have temperature data for the core? Like burn tunnel and heat riser temps? Anything under 900 celcius in the heat riser i consider not rockety enough.

You don't seem to be close to anybody i know with a Testo 330 II. That would be intresting to see if you can reach better numbers than Peter or Matthew, and make the stove last.

Bye.

Max.

PS: another question, what is your width to height ratio of the burn tunnel?

Satamax Antone wrote:So Gusmus, , you seemed to get cranky with me. No need to be.

I have questions tho.

Are the feed tube, burn tunnel and heat riser insulated?

How long have you been running it?

Do you have temperature data for the core? Like burn tunnel and heat riser temps? Anything under 900 celcius in the heat riser i consider not rockety enough.

You don't seem to be close to anybody i know with a Testo 330 II. That would be intresting to see if you can reach better numbers than Peter or Matthew, and make the stove last.

Bye.

Max.

PS: another question, what is your width to height ratio of the burn tunnel?

As I stated in reply to your earlier post. "All of the details are on the original thread". Nothing has changed except the front end which doesn't even get hot enough to burn your hand when placed on top.
As for your temperatures of 900C well, on a six inch system. I call "Bullshit" and on an eight inch system I'll call almost unless we all live in a perfect world of laminar perfection. 6" 600C, 8" 800C. Of course you have to take into account that internet never forgets and I quote.

"Thanks a lot guys.
Well, the next question which comes to my mind, do we realy need the hotest flame to burn everything. If we have a bit more air intake, than the ideal adibatic combustion, the gasses in the burn chamber and heat riser will somehow cool down. The thing would be to find the good compromise between proper burning through the burning lengh, and not too hot as not to melt things Since i'm a keen user of metal." You said it Satamax. Not me.

Yep, i said that, and i can tell you that the last volatiles are burned in the range of 900C° And yep, even a 6 incher is "in the main part of the burn" hotter than that, if there's not too much primary air.

I've brought firebricks to the orange glow in a 6 incher. In the feed, which is not the hottest part.

http://www.ceramicartdaily.net/PMI/KilnFiringChart.pdf

When i say metal is doomed, it's because i've managed to kill a J tube prototype in 14 burns. The gas bottle which was acting as an expansion chamber after the feed and burn tunnel colapsed under it's own weight. And the feed tube elbow turned to puff pastry by spalling, that the feed was unusable after 14 burns. That was 8mm thick hydraulic tubing, used in the industry, not some cheapo s235 type steel. The 8mm had turned to more than 2cm thick at the elbow.

Thoses 14 burns lasted about 32 hours total.

You can do anything you want with metal. I'm questioning your build only for one reason. If people follow you, and fail. Imagine that a metal part falls down in the burn tunnel and reverts the fire, smoking the whole house. Killing people in there. Who would be responsible?

Have you ever thought about this?

I lilke to see people inovating. But i have seen more metal build fail than succeed. (actualy, besides L tubes for cooking, no metal build ever impressed me)


And again, how many hours has this thing been burning for soo far?

There's another point in your original post

In this drawing

https://permies.com/t/40044/a/21422/Rocket00001.jpg

You state that the temp at the begining of the chimney is between 25 and 32C° on a regular basis? And your thing never stalled? Usualy we admit that 60C° is a good number to shoot for at the entrance of the chimney.

Gives you 40C° more than the hotest you would want to have a burn

Satamax. The stove has been running for about 6 years now without any problems until early this year when the firebricks in the burn tunnel started to crack and partially collapse. When I rebuilt the tunnel I decided to try and design a new front end which was a little bit more than the usual hole in the wall. Now if you look at the original drawing you will see that the steel insert only goes half way down the burn tunnel, this caused a bit of spalling in the last 10 centimetres of the tube so I decided to reduce the amount of steel insert to just over a quarter of the burn tunnel an expect to maybe have to replace or repair after about 5 years if at all since the main burn takes place much further inside the tunnel which is completely built of firebrick as is the vertical burn tube inside the barrel. Everything on the combustion side of the stove is insulated with expanded clay marbles mixed with heavy duty fire cement. I have no doubts at all about anything collapsing and since firing up the new front end I would reccomend people to at least try it since it gives an alternative to the "All or Nothing" approach. Where I live I don't want the mass to be running until maybe mid november until the end of march but it is nice to have the fire lit in the evenings from october and then again in april/mid may. With the new front end I can bypass the mass and use the stove as an ordinary but highly efficient wood burner in the cool to cold evenings without having the mass blasting out heat during the relatively warm daytime hours. When the daytime tempreature drops I simply switch over to the mass which sits at between 26 and 36ºC depending on the burn times but I have had it as high as 50ºC which was extremely uncomfortable to say the least. The mass (1 Cubic Metre) is built of ceramic coated tubing encased in high density concrete and took about 18 hours of continuous burning to reach 50ºC yet only 4-5 hours to reach 45ºC but once there held that temperature for quite a few days. I tend to take it up to about 28ºC and it'll hold that temperature indefinitely with a 3-4 hour burn each evening. That's enough to heat 115 Square metres of house quite comfortably at an average of 19ºC. In the main room where the Stove is situated (40 SQ Metres) the temperature is a steady 24ºC. If anyone is interested I'll post the front end dimensions and a drawing. The Mass and combustion side are the same as posted on the other link.
PS. No. it has never stalled although I notice now that when I bypass the mass, the chimney or exhaust is now much hotter since there is no mass to leech out the heat from the gasses. If you think about it. One cubic metre of concrete takes some heating so every last calorie is being soaked up until the mass becomes saturated and that I imagine is why the exhaust temperature is so low..

There's one thing i can explain.

Exhaust temperature is the result of several factors.

The main ones are:

the exchange surface inside the mass, the bigger that surface the colder the exhaust gases are going to be.

The time it stays in contact with that exchange surface, the longer gases stay in contact with the mass, the colder they get.

Difference of temperature. The biggest the temperature differential between exhaust gases and mass, the faster the mass will heat up, and the faster the gases will cool.

I should look up the heat storage specs of concrete on engineering toolbox. But i feel lazy. The temps you give me make me a bit dizzy because i can't do much with thoses.

Basicaly, what would be intresting is temp differential between mass gas intake, and exhaust. That we would see how much heat it soaks. That has to be a curve, soaking more with a bigger delta T and decreasing as flue gases and mass tend to reach the same temp.

And about the time it has been runing, i meant with the metal insert. Clay balls and fireclay is a perfectly good material for me. Lacks a bit of insulation for nutters like me. But fine nevertheless.

But i'm still not keen on your front end. Exept for the use of pellets, you would have been better off, may be , to switch to a batch front end.

http://donkey32.proboards.com/thread/1361/converting-8-6-batch

Ahh. But what I don't want, or should I say, the missus doesn't want. Is a batch anything. She wants a nice little fire where she can watch the flames dancing and casting patterns on the ceiling. If I wanted a batch whatever I would have built one. I now have this and without sounding blasé about temperature gradients, insulation characteristics, and exchange surfaces, etc, etc, etc,,,, it works, it works for me, it heats the house, it uses little fuel, it makes little or no smoke from the chimney, and it's mine. I don't really want to rock your boat Satamax, but if I'd wanted perfection then I'd have bought a good pellet burner and had a hell of a lot less fun. As it is, I enjoy my little experiment whilst reaping the benefit of a cozy cave to live in for little cost. I've achieved what I was looking for. Tell me. What is it that you are trying to achieve?

What am i trying to achieve? Stay alive from day to day

Help others. You included.

Nevermind.

http://www.youtube.com/watch?v=xX3COtw_YnE